Table of contents

Preface

2019 4th Asia Conference on Power and Electrical Engineering (ACPEE 2019) was held in Hangzhou, China from Mar. 28 to 31, 2019. ACPEE 2019 was co-organized by Auckland University of Technology and Hong Kong Society of Mechanical Engineers (HKSME), technically sponsored by Shanghai Jiao Tong University and Zhejiang University. The conference provides a useful and wide platform both for display the latest research and for exchange of research results and thoughts in Power and Electrical Engineering, Renewable Energy and Smart Grid and other topics. The participants of the conference were from almost every part of the world, with background of either academia or industry, even well-known enterprise. The success and prosperity of the conference is reflected high level of the papers received.

The proceedings are a compilation of the accepted papers and represent an interesting outcome of the conference. This book covers 11 chapters: Power Electronics; Power System Reliability/Quality; Transformers; Power System Control; Optimization; Distributed Generation; Energy Storage; Fault/Detection Algortihms; AI Applications; Transient Analysis; Power System Operation.

We would like to acknowledge all of those who supported ACPEE 2019. Each individual and institutional help were very important for the success of this conference. Especially we would like to thank the organizing committee for their valuable advices in the organization and helpful peer review of the papers.

We sincerely hope that ACPEE 2019 will be a forum for excellent discussions that will put forward new ideas and promote collaborative researches. We are sure that the proceedings will serve as an important research source of references and the knowledge, which will lead to not only scientific and engineering progress but also other new products and processes.

Prof. Tek-Tjing Lie

Auckland University of Technology, New Zealand

General Chair

Prof. Tek-Tjing Lie, Auckland University of Technology, New Zealand

Conference Committee Co-Chairs

Prof. Emanuele Calabrò, Institute of Industrial Technology, Italy Prof. Guojie Li, Shanghai Jiao Tong University, China

Advisory Committee Chair

Prof. Man Chung WONG, University of Macau, Macau

Program Chair

Prof. Moustafa Eissa, Helwan university, Egypt

Local Committee

Prof. Zhengzhi Lin, Zhejiang University, China Dr. Chengjin Ye, Zhejiang University, China

International Technical Committee

Dr. Khoa Dang Hoang, University of Sheffield, UK

Prof. Zulfiqar Khan, Bournemouth University, UK

Dr. Shuheng Chen, University of Electronic Science and Technology of China, China

Dr. Tosak Thasananuyariya, Metropolitan Electricity Authority, Thailand

Dr. Prakornchai Polratanasak, North Eastern University, Khonkaen, Thailand

Dr. Michael Bernard, University of Alberta, Canada

Dr. Mohamed Yahia Edries, Space Division National Authority for Remote Sensing and Space Science, Egypt

Dr. Thongchart Kerdphol, Kyushu Institute of Technology, Japan

Dr. Hany Farag, York University, Canada

Dr. Narottam Das, University of Southern Queensland, Australia

Prof. Dimitris Labridis, Aristotle University of Thessaloniki, Greece

Dr. Nickey Brown, Wright State University, USA

Dr. Jiafeng Xie, Wright State University, USA

Dr. Mohamed Dahidah, Newcastle University, UK Prof. Lei Chen, Wuhan University, China

Dr. Mehrdad Ahmadi Kamarposhti, Jouybar Branch Islamic Azad University, Iran

All papers published in this volume of IOP Conference Series: Materials Science and Engineering have been peer reviewed through processes administered by the proceedings Editors. Reviews were conducted by expert referees to the professional and scientific standards expected of a proceedings journal published by IOP Publishing.

Modular multilevel converter (MMC) is a new topology of voltage source converters. At present, the research on the flexible DC of this topology mainly focuses on the control strategy. The fault analysis and protection principle research is not complete enough, and it is necessary to analyze it in depth. The bipolar short circuit is the most serious fault type of the DC line. By analyzing the mechanism before and after the closing of the rectifier valve, the voltage and current transient voltages of the rectifier valve and the DC line are obtained, and a simulation model is built on the PSCAD to verify.

Considering the FB-MMC, a generalized pre-charging strategy is proposed for the MMC-based systems. It contains two stages, no control charging and controllable charging. The circuit model of the converter is established in the no control charging stage, and the submodule capacitance can be charged to about 37% of rated voltage. During the controllable charging stage, we proposed grouping charging strategy, the blocked and bypassed strategy of each group sub-module is formulated. According to the circuit model, the capacitance voltage of each module can be charged to the rated value through this strategy. Finally, we set up a 9 level full bridge MMC-HVDC simulation system in PSCAD/EMTDC. The charging strategies are simulated, and the results show that the proposed control strategy is feasible.

In a flexible DC transmission system with a large-capacity overhead line, a hybrid modular multilevel converter (MMC) consisting of the half bridge submodule (HBSM) and the full bridge submodule(FBSM) has become a research hotspot due to its self-cleaning capability of DC short-circuit fault. Under the operating conditions of reducing the DC voltage, due to the different charging and discharging characteristics of the half bridge submodule and the full bridge submodule, a capacitor voltage imbalance may occur between the two submodules. This paper first studies the number configuration of half-bridge submodules and full-bridge sub-modules in modular multilevel converters. Then, the capacitor voltage imbalance mechanism of the hybrid MMC sub-module is analyzed in detail, and the optimal control strategy of the capacitor voltage balance is derived according to the configuration requirements of the two sub-modules. Finally, a hybrid MMC-based flexible DC transmission system is established in the PSCAD/EMTDC simulation environment, low DC voltage operation of the system are simulated to verify the correctness and effectiveness of the control strategy.

The modular multilevel converter based multi-terminal HVDC (MMC-MTDC) system with hybrid DC breakers should consider the influence of the action of the DC breaker on the switching overvoltage, which puts higher requirements on the overvoltage protection of the system. Flexible DC demonstration project in Zhangbei will realize the first engineering application of hybrid DC circuit breaker. Based on this project, an overvoltage protection scheme for MMC-MTDC system is proposed. Firstly, this paper investigates the effect of the operation mode of the DC grid on the switching overvoltage level. Secondly, typical faults and the protection action sequence of various faults are analyzed in detail. The characteristics and laws of various switching overvoltage are deeply studied. Finally, the switching overvoltage of converter station is calculated on the basis of the control and protection system, and the recommended values of the insulation level of converter station equipment for the ±500kV MMC-MTDC system with hybrid DC circuit breaker are given.

This paper designs the control strategies and start procedure of MMC-HVDC. The start procedure consists of three stages, uncontrollable charging stage, controllable charging stage and power-raising stage. The current circuit is analysed and the equivalent circuit is obtained in uncontrolled charging stage. The computational formula of current-limit resistor is obtained in the uncontrollable stage. Two different control strategies to further charge the capacitors to the rated voltage in controllable charging stage are designed. Strategy one makes use of DC voltage control and balancing strategy of capacitor voltage while Strategy two divides the capacitors of one arm into two groups. In power-raising stage, to avoid the impact of power step, slope control is used in power outer loop. Finally, a simulation model is established in the PSCAD/EMTDC. The simulation results show that the effectiveness and rationality of the designed start procedure and control strategies

With the introduction of modular multilevel converter (MMC), the development of high voltage direct current transmission (HVDC) technology has been promoted. As flexible DC transmission technology is gradually extended to overhead line transmission, DC fault clearing and fault protection issues have become particularly important. In this paper, the current characteristics of different stages of DC short-circuit faults are studied for the overhead line true bipolar MMC-HVDC system. The simulation model of the true bipolar system is built by PSCAD/EMTDC software. The simulation results verify the correctness of the analytical calculation. Finally, in order to suppress the sudden increase of bridge arm current during fault, a bridge arm protection method for DC short-circuit fault is proposed. The simulation results show that the protection method can effectively protect the sub-module device in case of fault, and can Shorten the fault recovery time, this protection method effectively protects the devices of the AC system and sub-modules.

Many of UHVDC transmission projects planned and under construction are hierarchical connected to 500kV and 1000kV AC grid in China. Live tank circuit breakers are selected for switching 1000kV filters. During the development of 1100kV live tank circuit breakers, the closing inrush current and transient recovery voltage are key factors for structure of extinguishing chamber of circuit breakers. In this paper, the above factors are analyzed by simulation, and key technical parameters of 1100kV live tank circuit breakers for UHVDC converter station are proposed.

As the DC microgrid has low inertia, this paper draws on the virtual synchronous machine technology to propose and control a new virtual inertial control strategy. This control strategy enables the grid-connected converter to have both AC inertia and DC inertia. By small signal decomposition, the transfer function block diagram of the system is established. The effects of different inertial parameters on the system's AC inertia and DC inertia are studied. The dynamic characteristic analysis and simulation results show that the proposed virtual inertial control can effectively suppress the fluctuation of DC bus voltage and AC power and increase the AC and DC inertia of the converter.

In order to solve the imbalance distribution of reactive power in the power system caused by different line impedance in parallel muti-inverter system, This paper analyses the deficiency of traditional droop control and the causes of reactive current circulation. Double closed loop control based on inverter voltage and current, it studies the influence of different system parameters on the equivalent impedance of the inverter, according to the study it introduce virtual impedance, the real-time reactive power is distributed to a given reactive power through the inverter's control system, and then the inverter control system estimates the virtual impedance by deviating the reactive power from the given reactive power. Simulation results show that the method of adjust reactive power on line have certain effectiveness and feasibility.

Power electronic transformer integrates rich forms of electrical interfaces and is able to realize a flexible, accurate and continuous regulation of the network power flow. It's a promising power equipment to act as the 'energy router' in the energy internet, achieving a large-scale access and efficient utilization of distributed energy resources. To solve the DC-bus voltage fluctuation of PET caused by the randomness of the output power of microgrid, a coordinative control strategy between the input stage, isolation stage of PET and the microgrid is proposed. The frequency-domain analysing method is used compare the characteristics of the power fluctuation response under the proposed coordinative control strategy and a traditional control strategy. The simulation results indicate that the proposed control strategy can achieve the stability and fast convergence of DC bus voltage, which proves the correctness and advancement of the coordinative control strategy.

In this paper, by studying the Permanent Magnet Synchronous Motor (PMSM) position sensorless control strategy, a method for error compensation of current responsed by high frequency error signal is proposed. Since the high-frequency carrier current contained in the stator current causes the erroneous adjustment of the current regulator, the control system contains a high-frequency error signal, which affects the motor rotor position and speed estimation accuracy. The high-frequency error voltage signal is extracted in the stationary^{α − β} coordinate system, and the high-frequency error response current in the stator current is estimated, and the estimation system is compensated. The PMSM position sensorless control system based on the rotating high frequency voltage injection method and the Matlab-Simulink system model of the error compensation are established. The results show that the speed and position estimation are more accurate after error compensation, and the steady-state error is smaller, which improves the smoothness of the motor at low speed.

Supply power for important load in priority is the fundamental principle during power shortage. For the reason that the existing power load classification principle is too simple to compare the importance degree of loads at the same level, this paper proposed a comprehensive evaluation method of load importance degree. First, an indicator system is established to measure load importance. Then a comprehensive evaluation model is designed basing on improved rank correlation analysis method, which sets weights based on subject and object analysis and calculates the importance degree value according 4 indicators, including outage cost. Finally, evaluating the distribution network reliability with load importance degree. Simulation results on IEEE-RBTS BUS6 system shows the validity and practicality.

Considering power quality, a user-oriented and extended index system of power supply reliability has been built, and a comprehensive evaluation of power supply reliability based on improved entropy method in distribution network has been designed in this paper. Firstly, the paper has built an extended power supply reliability index system from 3 following aspects: the supply side, user side as well as the contrast, therefore, 7 new user-side indexes can reflect the real level of the power supply reliability by its continuity and availability, and 2 contrast indexes can reflect power supply reliability of the line among users in low and medium voltage; Secondly, considering its requirements and index characteristics, a comprehensive evaluation based on improved entropy method has been established. An initial index weights can be attained by this method, then, the weight matrix can be determined by a principle called 'overflowing-value punishment'. What's more the comprehensive values can also be attained after weighting and summation. Finally, its effectiveness can be verified by the result of case.

At present, the studies of power quality pre-evaluation of PV power station mainly focus on the internal mechanism modeling of PV power generation units, which makes the modeling and calculation process complex. Aiming at the situation mentioned above, this paper presents a power quality pre-evaluation method of PV power station considering its output elements. First of all, the paper establishes an equivalent model of PV power generation unit by taking the light intensity and temperature as the input, and the steady output current and voltage as output. Secondly, a power source model and a harmonic source model are paralleled to establish an equivalent model of single PV power generation unit in the working conditions. Then, the equivalent model of a grid-connected PV power station in Guangdong Province is built on the PSCAD/EMTDC. Finally the paper makes a detailed power quality pre-evaluation of the PV power station and verifies the practicality of this method.

The seismic disaster will cause serious damage to the power system. At present, the reliability evaluation of the power grid under earthquake conditions is mainly subjected to the approximate analysis of seismic performance, and the approximate analysis results can not meet the actual needs. In this paper, a reliability evaluation model of Power Grid considering the structural reliability of tower under earthquake conditions is proposed. The structural problems of tower and cable are analyzed directly by finite element simulation. The failure rate of transmission line is calculated by the structural reliability of tower and cable. After obtaining the reliability data of transmission line, the reliability of the power system under various seismic intensities is evaluated. Finally, the influence of the location of seismic source on the reliability of power system is analyzed. The results of the example analysis verify the accuracy and practicability of the proposed model and provide a reference for improving the seismic performance of the power system.

From the perspective of reliability and economy of distribution network, this paper combines the layout of network frame and the configuration of section switch and contact line, and obtains many plannings that coordinate economy and reliability. Firstly, considering the grid planning, a multi-objective optimization planning model of the distribution network frame with the lowest investment and operating costs and the best reliability index is established. When solving the model, the minimum spanning tree algorithm is used to avoid the generation of infeasible solutions and reduce the computational burden. This paper improves the minimum spanning tree algorithm, when algorithm iteratively generates a new solution, the sum of the reduction rate of economic index and the growth rate of reliability index is used to be the objective function in the iterative process, so that the multi-objective problem is transformed into a single objective problem. The preference factor of the decision-maker is given by weight assignment. And the algorithm is extended to multi-power planning. Secondly, considering the configuration of section switch and contact line, the nonlinear mixed integer programming model corresponding to the system is established, and the Pareto optimal solution set is generated by the NSGA-II algorithm. Then, the Pareto optimal solution set is converted into a series of corresponding planning schemes that the designer can select. Finally, the validity and correctness of the proposed method are verified by the analysis of single-source and multi-source distribution network examples.

The demand for reliable power supply in large cities is the major concern for both consumers and company, and power outages have uprising influence on economic losses and social impacts. With the continuing growth of underground cable ratio in Shanghai, the medium-voltage distribution network structures are experiencing changes. The choice of grounding method has considerable impact on operation safety and system reliability. It is crucial to carry out in-depth and systematic analysis on different grounding modes. This paper analyzes the technical route, insulation coordination, protection configuration and system reliability for neutral grounding mode for Shanghai distribution network with regard to the development status and safety requirements of urban medium voltage distribution grid, providing effective technical principles and engineering proposals for system planning and safe operation.

To discriminate inrush from an internal fault is a hot topic, as the inrush current may cause transformer differential protection to malfunction. Compared with Fourier algorithm, prony analysis can get amplitude and attenuation factor of one signal. Thus, prony analysis may have a better effect in discriminating inrush current. First, the energy concept of primary and second harmonic is first proposed based on prony analysis in this paper. Then, according to the study of attenuation characteristics of fundamental and second harmonic, it is found that the ratio of fundamental energy to second harmonic energy has a big difference in inrush current and internal fault. Thus, a novel method based on primary and second harmonic energy is presented. Simulation results of PSCAD prove the method to be correct.

The general data of industrial electromagnetics materials are given only for sinusoidal waveform, and mostly load is non-linear which may cause the harmonics effect. Steinmetz parameters, the well-known empirical equation, also differ under different frequencies and only for sinusoidal. Generalized Steinmetz equation and improved generalized Steinmetz equation are used to predicting the core loss under non-sinusoidal excitation. In this paper, a brief introduction of core loss calculation methods under non-sinusoidal excitations is discussed, and comparative analysis of under different harmonics orders and contents are presented. Ferrite N87 and Nano-crystalline 1K107 ring samples are magnetized as for experimental results. The experimental results show that the core loss depends not only frequency but also on the harmonics effect.

Identifying backbone grid has great significance to the differential planning of power grid, which can improve the ability to withstand natural disasters effectively. In this paper, the problem of exploring backbone grid is formulated as a mixed integer nonlinear programming problem and the optimization target should balance the survivability and cost. Then, the problem of searching for backbone grid is solved with improved biogeography-based optimization algorithm, and several improvement strategies are employed to enhance the convergence rate and precision of the proposed method. The simulation verifies that the mathematical model can identify backbone grid appropriately and the improved algorithm can figure out backbone grid more effectively.

With the development of electric market reform, electricity spot market pilot is about to be launched in China. However, facing more complex settlement process in a competing environment, the existing power metering system may not meet the requirements of modern power market. Thus, it is an urgent problem to determine the improvements performances based on the existing power metering system. This paper will focus on this problem and propose suggestions based on the experience of domestic and foreign electricity market. In this paper, electric power metering systems of Australia, Britain and China (Guangdong Province) is firstly studied and presented in five significant aspects, including market participants, market structure, metering point, acquisition cycle and business managements. Then, their commons and differences will be further analysed and compared as reference of Chinese practice. Finally, suggestions of power metering system construction are proposed in China' electric power market reform.

For solving the difficulty of extracting the disturbing characteristics of the signals in power quality processing, and restraining the noise in the process of sampling, an improved extreme-value lifting morphological wavelet method is constructed. Firstly, morphological extreme-value operator is chosen to be the prediction operator and update operator, then the max-lifting and min-lifting morphological wavelets are constructed. Secondly, the improved extreme-value lifting morphological wavelet method is designed to further highlight local maxima and minima information of the disturbing signals based on the first step. Finally, the signals are dealt with this method, and the detail coefficients can be obtained, which have kept the disturbing characteristics of the signals. The result of simulation and analysis shows that this algorism owns the trait of simple, exactness, and de-noising.

Due to periodic variation of power signal and various disturbances present during sampling process, resulting background gradient affects the accuracy of disturbance detection. In order to solve this problem, this paper proposes a power quality transient disturbance location method based on morphological edge detection, and introduces a soft threshold quantitative evaluation method to improve its accuracy. Firstly, an evaluation method of filtering effect is proposed, and original signal is filtered by adaptively choosing size of structuring elements. Then, Top-Hat transform of morphological gradient is performed by flat structuring elements to suppress background gradient, and the location result is initially obtained. Finally, combined with soft threshold processing method, the location of power quality transient disturbance is realized. Simulation analysis of a series of power quality transient disturbances shows that this algorithm has accurate location results, strong capacity of resisting disturbance and good versatility.

Ex-service SF₆ adsorbent is toxic, and its direct dumping may cause environmental damages. Therefore, studying the environmental-friendly processing of ex-service SF₆ adsorbent has important social values. In this study, the adsorption components of the ex-service SF₆ adsorbent were analyzed by thermogravimetry. In order to study the most economical and effective regeneration method of SF₆ adsorbent, the regeneration technology of vacuum heat treatment was proposed, and the regeneration theory of vacuum heat treatment concerning adsorbent was elaborated, then followed by the experiment of vacuum heat treatment. By combining with infrared spectroscopy, the content change of harmful ingredient in adsorbent was analyzed, focused on the confirmation of vacuum heat treatment regeneration temperature, regeneration time and vacuum pressure, and the test verification on adsorption isothermal curve was performed to determine the desorption capacity of SF₆ molecular sieve adsorbent recycled. We found that vacuum heating can increase performance recovery rate by 85%–90%.

Oil-immersed hollow reactors have been applied to high-voltage frequency-modulated resonant power supplies due to their favorable linearity and high insulation strength. A high-quality reactor is the key component of a high-voltage test system. The characteristics of loss and temperature-rise characteristics are the core factors affecting the quality factor of the reactor. In this paper, a finite-element numerical simulation model was established based on a large capacity series resonance test system for a 500-kV submarine cable in China. The eddy current loss, AC resistance loss, and circulating current loss of the oil-immersed air-core reactor were calculated. With these as a foundation, the flow and temperature field distribution characteristics were obtained for an oil-immersed hollow reactor through the coupling of magnetic heat and flow field. Finally, the temperature distribution characteristics of the reactor were compared with the dates obtained from the release testing, and the reliability of the calculation model was verified.

Overvoltage will occur on transformer windings when high frequency waves such as lightning strike and Very fast transient overvoltage(VFTO) intrude into transformer windings. The model and parameters is the basis of calculating transient overvoltage in transformer windings. In this paper, partial element equivalent circuit (PEEC) is used to calculate High Frequency Voltage on transformer windings. the inner grid of conductor through which conductive current passes and the surface grid of conductor with charge distribution is used to transform into the inductance unit and capacitance unit of PEEC respectively. The mutual capacitance between different windings is solved by PEEC. The change regulation of resistance coefficient of transformer windings under different frequency waveforms is analyzed, and the internal voltage of transformer under different frequency applied voltage is solved. The results show that the self-inductance of winding decreases slightly with the increase of applied voltage frequency, and basically remains unchanged in high frequency band. With the increase of frequency, the voltage waveform on winding turns decreases rapidly.

Methyl ethyl ketone dissolved in transformer oil is a new chemical mark of thermal insulation degradation. As an effective detection method, Surface-enhanced Raman scattering (SERS) could directly perform rapid detection for methyl ethyl ketone in transformer oil without complex preprocessing steps, which can provide in-situ capability to overcome the shortcomings of traditional method. First, sliver nano-bulks were synthesized on the copper foil surface by the galvanic displacement. silver nanobulks were used as the SERS substrate to detect standard transformer oil samples with different methyl ethyl ketone concentrations. The SERS peak at 763 cm^-1 was selected as the characteristic SERS peak for qualitative and quantitative analyses. In addition, the quantitative analysis model was built between the Raman intensity at 763 cm^-1 and methyl ethyl ketone concentrations by applying the least square method. Experimental results showed that SERS method could be used to analyze methyl ethyl ketone dissolved in transformer oil quantitatively and effectively. With further improvements of the detection limit, the SERS method will provide a useful approach to achieving rapid in-situ analysis for methyl ethyl ketone dissolved in transformer oil.

In view of the operating characteristics for voltage sags of AC side of the power electronic transformer(PET), a low-voltage ride through(LVRT) strategy adapted to bidirectional power exchange of PET is proposed for the purposes of maintaining the system stability, assisting the system voltage recovery and protecting PET safety. During the asymmetric voltage sag, the negative sequence current of PET is eliminated to ensure the symmetry of the injected current. According to the degree of positive sequence voltage sag, the reactive current injection is provided to assist in voltage recovery. According to the PET active power condition before the voltage sag, the level and direction of which are maintained as far as possible without exceeding the limit, for which the disturbance to the AC and DC grids is reduced. Finally, the effectiveness of the proposed LVRT strategy is verified by simulation model.

Fast pyrolysis of transformer oil occurs at local high temperature caused by internal fault in power transformers and this may lead to transformer insulation deterioration. Because numerous subjects such as electrical, material and chemistry are involved and further research of microcosmic reaction mechanism is limited. In this paper ReaxFF reactive force field in which atom connectivity is presented by bond order is introduced to carry out reactive molecular dynamics simulation for transformer oil molecular models and their pyrolysis mechanism at high temperature are investigate. Alkanes C₁₆H₃₄, cycloalkanes C₁₆H₃₀ and aromatic hydrocarbons C₁₆H₁₈ with the same C atoms number 16 are taken as transformer oil examples and initiation pyrolysis mechanism, molecular interaction and products distribution during the whole process for different types of molecules at high temperature are simulated based on ReaxFF reactive force field reactive molecular dynamics. The results indicate that the pyrolysis of these three molecules is similar, the unimolecular dissociation is the main pathway at the early stage of pyrolysis while at the later period it is intermolecular radicals interaction dominated; the final products are mainly small hydrocarbons and radicals, such as C₂H₄, C₃H₆, CH₄, H₂, C₂H₆, C₃H₄, while most of the large hydrocarbons and radicals whose C atoms more than 6 mainly serve as intermediate products and decompose into small hydrocarbons and radicals with reactions going on. The difference is that the saturation of generated small molecule hydrocarbon increases for C₁₆H₃₄, C₁₆H₃₀ and C₁₆H_18.

In order to improve the economic life and reduced life cycle cost of the power transformers, the power transformer life cycle calculation model was built which considered key factors in all sections of the life cycle. Then the economic life evaluation method was researched to get the least total cost in the life cycle. At last, Practical example was calculated to obtain the life cycle cost and verified the accurateness of the method. The research result could provide theoretical support for equipment LCC management.

The detection and localization of partial discharge (PD) in air-insulated substations by ultra-high frequency (UHF) technology is widely studied. Existing UHF PD localization system mainly focus on time-difference of UHF signal, which requires very high synchronized sampling rate. This paper proposes a received signal strength (RSS) based angle of arrival (AoA) method by a circle UHF wireless sensor array. An AoA estimation scheme is derived through the radiation pattern of designed UHF antenna. Interpolation and neural network are applied to improve the AOA resolution. A field test is performed to verify the effectiveness of the proposed PD localization system. The results show that the estimated error on average is below 7°. Compared to the time-difference-based method, the accuracy of our designed system is more feasible for practical application considering its significant low-cost feature.

The vibration of transformer is closely related to windings, so researching on vibration signal of power transformer has potential to realize online detection of winding looseness. In this paper, a series of tests have been made to obtain vibration signal by setting winding looseness on a 10/0.4kV three-phase transformer. A linear fitting equation has been obtained by fitting the amplitude of the 100Hz component of the vibration signal under different short-circuit currents. The results show that the slope of the fitting equation will increase when the winding becomes loose. The research results show the potential of this method in condition monitoring of power transformer.

In order to study the effect of load on the transformer vibration noise. In this paper, a S13-M-200/10 distribution transformer is taken as the experimental subject and an experimental platform was built to collect the vibration noise signals of the transformer under no-load, short-circuit, resistive load, inductive load and different load rate. These signals are used to study the vibration characteristics of transformers under different load rate and load characteristics. The results show that the amplitude of the 100Hz fundamental frequency increases with the increase of the load rate, and the amplitude of other frequency basically has no change. The inductive load will cause the increase of the amplitude of 150Hz and 250Hz components, and the amplitude increases with the increase of the inductive load. The research results of this paper provide a theoretical basis for the condition monitoring of transformers based on vibration noise signal.

For the condition that single-phase short circuit current exceeds three-phase short circuit current occurs on some of Shandong 500kV substations' 220kV bus, this paper studies the principle of limiting 500kV autotransformer's short circuit current by installing small reactance. Considering that installing small reactance at 500kV autotransformer's neutral point influences the zero sequence circuit, this paper suggests to configure independent relay protection on small reactance which aims at supervision the short circuit current and improving reliability. Protection setting for neutral-grounding small reactance is proposed. Simulation results and protection setting software show the effect of limiting short circuit current by installing small neutral-point reactance.

AC filter bank switching in the HVDC inverter station may cause harmonics which leads to commutation failure. This paper analysis the characteristics of AC filter switching and build the transient progress circuit and mathematics model. And the time-response solution of AC filter overvoltage is acquired, the AC voltage magnitude decrease and distortion can be calculated. Commutation caused by these reasons was analyzed. And a consecutive commutation failure mitigation method is proposed. The algorithm was verified in the PSCAD/EMTDC.

With the wide application of UHVDC in long-distance and large-capacity power transmission, the current power grid has developed into a complex AC-DC deep coupling system, which poses a serious challenge to the voltage safety control of the system. Based on the voltage sensitivity of AC/DC system, this paper presents a voltage optimization control method for integrated coordination of AC/DC system control variables. In this control method, a linear constrained quadratic optimization model with minimum control cost is constructed to coordinate the control variables of AC/DC system and correct the voltage amplitude deviation. The potential of UHVDC system to participate in voltage control is studied by optimizing the control quantity of rectifier side and inverter side converters. The simulation results of AC/DC hybrid system show that the proposed optimal control method can effectively coordinate the control quantity of AC/DC system and ensure the voltage operation in a safe range.

This paper mainly analyzes the transformer fault evolution rule. Meanwhile it analyzes the correlation relation between transmission and transformation equipment fault characteristic parameter and the fault. This paper establishes the fault characteristic parameter multi-factor forecast model and the equipment fault diagnosis model, which realizes the transformer fault occurrence probability, the fault type and the fault position real-time accurate forecast. It includes data acquisition and preprocessing, multi-factor prediction of fault characteristic parameters, correlation analysis of characteristic parameters and fault types, failure probability of various faults, equipment failure probability and fault diagnosis. In this paper, a transformer characteristic parameter prediction model based on environment and other factors is proposed. The example analysis of transformer characteristic parameter multi-factor prediction model based on multiple linear regression (MRL) shows that the multi-factor prediction model can effectively consider the influence of external factors on the variation of characteristic parameter, and the prediction accuracy is higher.

Based on the equivalent circuit of transformer, this paper deduces the calculation method of short-circuit impedance of three-phase transformer based on multiple measurement data. Taking a single-phase transformer as the research object, the 'magnetic field-circuit' simulation model is established. The normal operation and winding deformation caused by different axial displacements are simulated and analyzed. The results show that short-circuit impedance changes when transformer winding is axially deformed, and the degree of change is related to the degree of deformation. Compared with the normal situation, the short-circuit impedance increases by 52.1% when the four transformer coils are moved 15 mm each. Therefore, on-line monitoring of the transformer short-circuit impedance can reflect the abnormal deformation of the transformer winding to a certain extent.

Transformer is a key equipment in the power system, and it is very important to accurately evaluate its operating state. In this paper, a new method is proposed to evaluate the operating state of the power transformer based on the genetic projection pursuit model. The proposed method can provide a more objective evaluation result for the health condition of the transformers compared with the traditional methods. Firstly, a three-layer evaluation index system is established with the precautionary test, oil chromatographic analysis and insulating oil properties as the core content. And then, the grading standard of the lowest level index in the indicator system is established. Secondly, the genetic projection pursuit model is used in combination with the grading standard to obtain the intermediate layer evaluation results, which overcomes the disadvantages of the traditional transformer evaluation method which is greatly influenced by subjective factors. Finally, the eigenvalue weighting method is used to integrate the intermediate layer evaluation results to obtain the final result. Case study results show that the evaluation method of transformer operating state based on genetic projection pursuit model is reasonable and effective.

The safety, stability and reliability of electrical equipment are directly related to the operation of the electrical system. Discovering various electrical equipment problems and effective treatment of the problem without delay will minimize the probability of electrical equipment failure. In electrical equipment monitoring and maintenance, Application of real-time monitoring is one of the most important elements. Real-time monitoring node can detect equipment failure promptly which will avoid the expansion of accident caused by the long test period or manual inspection. Working time of online monitoring nodes is limited by power consumption of node itself. Application of routing protocol can optimize energy consumption and extend working time of nodes.

Voltage source converter multi-terminal DC system(VSC-MTDC) have been used in many applications due to their many advantages. With conventional droop control, the voltage and power of the stable point are on a straight line with a specific slope. When subjected to a power disturbance, the voltage quality may be deteriorated or the power distribution effect of the converter station may be deteriorated. In this paper, a new adaptive control strategy is proposed for VSC-MTDC. The control system focuses on voltage quality at low loads and power distribution at high loads. It not only ensures voltage quality but also meets power distribution requirements. Simulation results are provided to verify the validity and effectiveness of the proposed method.

In this paper, a consensus-based, nonlinear, and Lipchitz-continuous distributed secondary control (DSC) method is proposed to coordinate all the distributed generators (DGs) in an islanded AC microgrids (MGs). This proposed DSC strategy can not only guarantee the restoration control for frequency and voltage, but also realize an accurate active power sharing control for the whole microgrid system. Through introducing a nonlinear, Lipchitz-continuous dynamic from Beta Probability Distribution Function (Beta PDF), the convergence speed of DSC is accelerated, the finite-time convergence of DSC is ensured, and the transient overshoot of DSC is diminished comparing with traditional DSC. Moreover, the common chattering phenomenon in non-Lipchitz DSC scheme is eliminated. The stability and performance of the proposed DSC are also analysed in this paper. An islanded AC microgrid test system with four inverter-based DGs is built in MATLAB/SIMULINK to further validate the effeteness of the proposed DSC strategy.

In this paper, finite control set model predictive current control strategy for five-phase permanent magnet synchronous motor is analysed. At first, virtual voltage vectors are adopted to avoid including all the 32 voltage vectors of five-phase inverter into the control set. Besides, under different rotor speed, estimated voltage vector is predicted in advance so that a new online updated adaptive control set can be established with proper voltage amplitude and only three vectors. Consequently, current ripples and computational burden can be much reduced. At last, experimental results are presented and indicate the performance improvement of the proposed control strategy.

The cascade PID control system used in the main steam temperature control of traditional thermal power plants has large hysteresis and large inertia characteristics. In order to solve the above problems, the program of heat transfer process of main steam and boiler flue gas is built based on Matlab. The amount of desuperheated water obtained by the program ensures that the main steam temperature of the boiler is the target temperature. Then the heat transfer calculation program is imported into the multi-model switching control system simulation platform based on heat transfer calculation built by Simulink. The results of simulation show that the multi-model switching control system based on heat transfer calculation solves the problem of large inertia and large delay of the main steam temperature successfully, and the control system can adapt to changes in boiler load.

Wind-solar hybrid generation system can significantly improve the utilization efficiency of intermittent renewable energy as it can make full use of the complementarity of wind-solar. Meanwhile, it will affect the low frequency characteristics of power system. Effect of different wind-solar accommodation conditions on low frequency oscillation characteristics of power system are analyzed based on IEEE 2-area 4-unit system. Eigenvalue analysis and dynamic time-domain simulation are adopted to figure out the influence, including different factors such as separate integration, grid-connected integration points and hybrid capacity ratios of wind-solar.

With the global energy crisis and environmental problems in recent years, the calls for energy conservation and emission reduction is getting higher and higher, and while the research on smart grid in various countries is deepening, The development of electric vehicle-electric grid (Vehicle to Grid, V2G) has become the focus of all countries in the world. This paper first expounds the background and related concepts of V2G generation, and proposes the key point in V2G: V2G control model. The second section of the article introduces the work related to the traditional V2G model. In the third section of the article, the new technologies such as blockchain are introduced and combined with the traditional V2G control model, and finally proposes a new blockchain-based model of distributed electric vehicle control system.

As China increasingly interconnecting power system, more and more factors are interfering with the stable operation of the power system. Due to the lack of system reactive power and the overload, resulting in the increasingly problem of low voltage amplitude. Voltage is a measure of whether the power system operation is basically normal index, the voltage level of the power network determines whether the whole power system is stable or not. The dispatcher and operator need to answer any specific challenges to solve the under-voltage in training simulator. In this paper, based on the analytical sensitivity method, the basic principle of the low voltage problem is solved by the method of load shedding and reactive power compensation. Then the low voltage control method is optimized from two aspects of the load shedding load and reactive power compensation. The reactive power compensation with high sensitivity is presented. If the voltage of the compensation is not returned to the allowable range of the state, cutting the load operation according to the magnitude of the load-shedding sensitivity. Using power system simulation software to build a low voltage model of the IEEE-39 classic power system for the sensitivity index and the low voltage optimization control methods are analyzed and verified.

This paper investigates the concept of Virtual Synchronous Generator (VSG) and analyses the working principle of common VSG control technology. With the promotion of Vehicle-to-Grid(V2G) technology, large-scale power electronics devices will be connected to the grid. Consequently, the stability of the grid will be influenced by the lack of mechanical inertia and system damping within these power electronic devices. The extant normal control methods are difficult to cope with this issue. Accordingly, a VSG control technology is proposed by this study, which can be applied to V2G system. Moreover, the mathematical analysis of this control method is also suggested in this research. This control method provides mechanical inertia and system damping, which is similar to synchronous generators. It also can achieve the accurate control of power. The original P/Q-U-I three-loop control is simplified to P/Q-I dual-loop control in the condition of not losing the inertia of the converter. Ultimately, the simulation examines the accuracy and effectiveness of the control method.

In this paper, the event of low-frequency power oscillation caused by power system stabilizer (PSS) field test in a power plant is introduced, and the mechanism of oscillation is analyzed. In view of the existence of several dominant components in this low frequency oscillation accident, an improved measure is proposed to achieve the disturbance source localization. Based on fast Fourier transform (FFT) decomposition of active power and frequency in steady-state oscillation, several dominant components of the oscillation are obtained. By superimposing the non-periodic components of the oscillation energy for several dominant modes, the disturbance source of the low frequency oscillation accident is determined.

When the wind power is sent as the interface by the line commutated converter, the vector-controlled doubly-fed wind turbine will be difficult to operate without power supply support, and it is impossible to send the wind power through the HVDC transmission system on a large scale. Future planned land-based wind power bases are becoming more remote and may not contain synchronous units. Therefore, it is extremely urgent to design a dual-feeder control strategy that can operate independently. In this paper, the control target of the doubly-fed turbine is changed to control the stator voltage and frequency. An improved control strategy of the doubly-fed turbine in the weak synchronous support system is proposed. The doubly-fed turbine will have the ability to send out through the line commutated converter. The simulation analysis of the wind power access weak synchronous support system sent by the HVDC transmission system is carried out. Under the natural wind disturbance, the sending end and the receiving end communication system disturbance, the doubly-fed turbine can quickly resume normal operation. With the effectiveness of this control strategy, the doubly-fed turbine can operate independently even if it loses its synchronous power supply.

There is an inherent limitation when unbalanced faults in AC system are studied in large scale AC/DC power systems with electromechanical transient simulation. In order to make the electromagnetic transient simulation which is accurate in these situations possible, dynamic reduction must to be done. A method based on support strength of generators is proposed. According to the connection form of low-voltage network with 500kV skeleton buses and whether there are generators in it, three reduction schemes are used to replace the corresponding low-voltage network. The dynamic parameters of equivalent generators are obtained by a time domain aggregation method. The equivalent results of planning data of East China Power Grid in 2020 show that, the method has high accuracy in power flow analysis as well as short circuit calculation. The proposed method greatly simplifies the original system while the characteristic of dynamic response remains.

In order to deeply study the influence of PV on the stability of power system, it is necessary to accurately reflect the external dynamic response characteristics of the PV system, and accurate PV system parameters are the key factors. For this reason, the moth-fire optimization algorithm is introduced to solve the PV system parameters value. This paper models the PV system and find out the key parameters of it. The active power and reactive power response curves of the grid are measured to identify the parameters of the PV based on the moth-fire optimization algorithm. The results of the example show that the curve fitting effect is better, and the feasibility of the proposed identification algorithm is verified.

As an important measure for structure optimization, the network reconfiguration has been drawing attention of scholars at home and abroad. At present, the general goal for network reconfiguration is to reduce network line loss achieving load balance. In this paper, the reconstruction methods for distribution network considering closed loop constraints is proposed from the perspective of load transfer between different loops to improve closed system reliability. After Dongjing Town distribution network verification, this method has shown important theoretical significance and high practical value.

In order to alleviate the heavy air pollution problem in China in recent years, power energy alternative loads, such as electric vehicles, are widely integrated into distribution networks, which has a significant impact on power supply capability of distribution networks. In this paper, considering the randomness of electric vehicles, probabilistic multiple scenarios generation method is proposed based on Latin hypercube sampling method, Cholesky decomposition and synchronous back-off reduction, realizing the quick scenario generation with the balance of scenario number and precision. Based on probabilistic multi-scene, taking the power supply ability of distribution network as the main objective, a robust operation optimization model of distribution network containing electric vehicles is established in order to optimize the opening and closing status of the switches. Ant colony algorithm based on the Pareto optimal is adopted to solve the model. A modified IEEE 33 node system is used to verify the effectiveness of the model and algorithm, and simulation results show that the proposed method can effectively promote the power supply ability of distribution networks, and can greatly improve the computational efficiency of the model in the case that lots of uncertain parameters exist due to large-scale integration of electric vehicles.

The rapid development of renewable clean energy and low-carbon transportation has brought new opportunities and challenges to the safety and economic operation of power system. This paper studies the economic dispatching operation of the power system that contains clean energy and large-scale electric vehicles, and establishes the objective function of minimizing the amount of discarded wind power and the lowest cost of thermal power generating units. In order to improve the optimization efficiency, the original system is decoupled into the wind-vehicle-hydro subsystem and the thermal power subsystem according to the characteristics of multi-source output. The two subsystems are connected by the load balance and the reserve constraints of the system, and their respective scheduling models are given respectively. In this paper, an improved random black hole particle swarm optimization (IRBHPSO) algorithm with fast convergence and effective avoidance of local optimization is proposed by combining the black hole theory and particle swarm optimization. The effectiveness and superiority of the improved algorithm were verified on a 10-unit test system. Finally, this paper modifies the IEEE-RTS system according to the proportion of installed capacity of the Northeast Power Grid. The simulation results verified the feasibility of the proposed optimal scheduling model and the effectiveness of the algorithm, which provides strategies and feasible suggestions for the large-scale electric vehicles to participate in the economic dispatching operation of the power system.

This paper is focus on the coupler design of wireless power transfer (WPT) system for Electric Vehicle(EV). The author describes the coupler circuit model, design principles and steps, calibration methods and magnetic shielding methods for the coupler. Four shielding methods are simulated and compared in this paper. Through simulation, the author believes that aluminium plate shielding is the best for magnetic shielding, but it will cause more losses. Therefore, we need to do a more optimal design in the next study.

The particle swarm optimization algorithm with adaptive weight and Newton-Raphson method are studied to connect the distributed energy to the grid in this paper. We will discuss the research status of the current stage of the project. The basic principles and processes of particle swarm optimization algorithm and Newton-Raphson method are expounded, and their improvement and combination are made (as well as their improvement and combination ) so that they can optimize reactive power for networks with distributed energy better. Then the improved algorithm is applied to the IEEE-14 and IEEE-30 models and the reconstruction results are analyzed. The network loss and reactive power of the reconstruction network are declined, the voltage quality is improved. The SIMULARTOR software is used to establish and calculate the power flow of original model and reconstruction model of IEEE-14 and IEEE-30 respectively. The economic factors with grid supply point and connected capacity are analyzed to obtain the best ratio of power system at the same time. Compared with the above results, the results are basically consistent, and the accuracy and reliability of the algorithm are verified. Finally, considering the economic factors of the system, adjusting the connected capacity of the distributed energy-wind power and photovoltaic, and obtaining the best access ratio (proportion), the economical efficiency of the system is improved, and it has referential value.

At present, China's power system is developing in the direction of AC-DC parallel connection. AC-DC hybrid transmission has become the inevitable pattern of China's future power grid. In the operation of AC/DC hybrid system, the optimization of multiple indexes is often considered. One of the economic problems of system operation is how to minimize the operation cost of the system. This requires the optimal solution of a system of nonlinear equations with constraints. Among the existing algorithms, the interior point method has excellent convergence performance and has been widely used in power system. In this paper, the basic principle of interior point method is introduced, and the interior point method is used to optimize the AC and DC power flow obtained. With the network operation cost as the objective optimization index. The Matlab software is used for programming and simulation calculation. On the basis of verifying the effectiveness of the algorithm, the algorithm is transplanted into the large network for calculation and analysis, and the adaptability of the test algorithm.

The development of distributed generation will be affected by the policy, and become more market-oriented. The impact factors of the future layout are various. In order to accurately predict the future layout of distributed generation and guide the planning, this paper presents a layout prediction method for distributed generation by multi-weight optimization. The method takes different impact factors into consideration and use the historical data to determine the weights of the factors with optimization method. The method can predict distributed generation layout in the target year accurately. The case of the distributed photovoltaic development in Shandong shows that the central region will become the main development region.

With the development of distributed generation technology and the requirement of power system flexibility, the research on multiple flexible resource optimization is carried out. Based on the traditional optimal configuration of wind-solar-hydro-storage system, this paper takes electric vehicle into consideration. Firstly, the model of each flexible resource is established. Then, a comprehensive evaluation index system is built. Taking the flexible resources in a city on the eastern coast of China as a case, multi-objective grey wolf optimization algorithm and entropy weight method are applied to do the optimization and evaluation. The simulation result shows that in the optimal configuration, not only the renewable resources can be effectively utilized, but also the requirement of load in different period can be meet. Moreover, the total investment can be greatly reduced. In addition, the participation of electric vehicles can not only improve the performance of the hybrid system, but also increase the income of EV holders.

Distributed renewable power generation has obvious volatility and randomness. It has different impacts on voltage, power loss, power quality and so on with different integration schemes in distribution network. It could improve the distribution network voltage level and reduce the power loss with reasonable integration scheme. Conversely, if the integration scheme is not reasonable, it will have bad impacts on power loss and voltage level of the distribution network. TO achieve the optimal planning scheme of Distributed renewable power Generation, a optimal planning method has been proposed in this paper. In the method, the minimum power loss of region distribution network as the optimization objective, long-term sequence simulation with wind energy, solar energy and load actual dates for at least one year in a row has been used to get the annual power loss and voltage qualified rate on different integration schemes. A model is verified by an actual case, which is a large-scale distribution network including multiple feeders. It is shown that the feasibility of the integration scheme. Secondly, the operation requirements of Distributed renewable power generation have been proposed based on the simulation analysis of impacts on voltage distribution of Distributed renewable power generation with PQ and PV operation mode. It is shown that appropriate voltage control strategy could be used to enhance voltage qualified rate.

In order to improve the utilization efficiency of photovoltaic system (PV system) and battery energy storage system (BESS) in photovoltaic and battery energy storage integrated electric vehicle (EV) charging stations, the capacity of PV system and BESS need to be allocated reasonably. In this paper, the maximization of the net annual financial value is used as the objective function of photovoltaic and battery energy storage integrated EV charging station in its whole life cycle. The control strategy of BESS is proposed based on time-of-use pricing. And then the optimization configuration model of PV system and BESS capacity is built. The economic efficiency of EV charging stations is compared and analyzed with actual test system when PV system and BESS configurating. The results indicate that the income and investment payback period of charging stations can be significantly improved through the reasonable configuration of PV system and BESS.

Regarding day-ahead optimization dispatch in distribution network containing large-scaled distributed generations (DGs) and electric vehicles (EVs), this paper proposes an optimization dispatch method based on conic programming. A model for dispatch that can optimize the EV aggregator charging power and the output of DGs is established. The proposed model takes the constrains of EV charging energy and charging power into consideration. In addition, DG can curtail the active power in the model to guarantee the operation safety. Then nonlinear optimization dispatch model are transformed and relaxed into second-order cone programming model to be solved. The optimization dispatch method proposed in this paper is verified by the IEEE33 node test system.

The traditional network structure cannot be suitable for the connection of large-scale distributed energy resources, thus the high penetration of distributed energy resource (DER) will have destructive effects on the security and reliability of the traditional distribution network. The paper proposes a new distribution network structure to increase the maximum allowable penetration of DER. Firstly, the model and method of the new distribution network structure are presented. Secondly, the theory basis of increasing the DER penetration by the new network structure is proved. Finally, the proposed model and method are applied to the typical test case. And the simulation results show that compared with the traditional structure, the new distribution network structure can not only increase the maximum penetration of distributed energy resource greatly, but also realize the high energy efficiency, reliability and sustainability. Therefore, the issue of future distribution network security with high penetration of distributed energy resource can be well solved by the new distribution network structure proposed in the paper.

Multi-microgrid (MMG) system consists of several microgrids (MGs) close to each other in space, and is more resilient to uncertainties and economical in operation than single MG. To coordinate the different goals of MMG system and individual MGs, a hierarchical dispatch structure is firstly established in this paper. Based on this, a two-stage dynamic economic dispatch (DED) scheme is then proposed to achieve the compromise between global and local scope. In Stage I, MMG system's operation cost is minimized to determine the power exchange among MGs, while in Stage II, each MG's purchased power from main grid is optimized to realize local economy. Finally, numerical tests are performed on a triple-MG system and different cases are studied to demonstrate the effectiveness and feasibility of the proposed dispatch strategy.

With the rapid development of distributed generation and advancement of power system, the integration of generation and distribution becomes an important operation mode in the future and distributed generation helps to improve the economy of incremental distribution. This paper quantifies the main cost-benefit of generation and distribution integrated system, then proposes an economic analysis method of the distribution integration system, which takes into account the transformation of power grid caused by high penetration distributed generation. Based on the analysis of typical scenarios, the conclusions can provide guidance for the planning and operating of generation and distribution integrated system.

The industrial park has become an important experimental area for power reform. Under the conditions of incremental distribution market liberalization, diversified power sources and loads, the investment interface of park integrated energy system has been divided, investment entities have become diversified, and the analysis of investment benefits has become complex. The paper proposes the park IES operation models on different interfaces, studies the methodology of calculating the full lifecycle investment benefit of different components of park IES. Based on the typical cases, it proposes the future direction of business development of park integrated energy service provider.

With the large-scale access of intermittent renewable energy, the active distribution networks (ADN) is facing great challenges on achieving full consumption and efficient use of intermittent renewable energy on the premise of ensuring safe operation. To resolve these issues, a novel multi-period robust dispatch strategy for ADN based on scene analysis method is proposed in this paper. Then, the second-order cone relaxation (SOCR) is used to transform the original model into a mixed integer second-order cone programming (SOCP), which gains as much improvement as possible in computational performance at the expense of as few losses as possible in accuracy. Finally, numerical test on the modified IEEE 33-bus test system demonstrates that on the premise of realizing the maximum utilization of DG, the proposed strategy can also achieve the purposes of energy-saving, loss reduction and improvement in voltage level.

In this paper, a supply and demand matching algorithm for industry park level energy systems is proposed. The algorithm can provide the configuration scheme of distributed generators installed capacity in line with the given load demand. Comprehensively considering the output characteristics of distributed sources such as wind and photovoltaic generators in different timeframes, the outputs of distributed generators are classified into several typical modes, and the installed capacity of distributed generator is matched in line with the representative output mode and the load demand curve so as to realize the balance of energy supply and demand in the industry park. The energy storage device is used to balance the energy due to the asynchronism of the distributed generator output and the load demand. The capacity requirements of the battery under various installed capacities of distributed generators are provided. The proposed algorithm is programmed in MATLAB and verified by the actual data of an industry park in northeast China. The results show that the proposed algorithm can comprehensively consider the output characteristics of distributed generator in different time ranges, and provide reasonable matching schemes of energy supply.

Considering that the information uploaded by distribution terminal is often lost or wrong in actual operation, which leads to misjudgement, this paper proposes a new fault location method based on multi-source information fusion technology. The advantage of this method is that multi-source information is used for fault location, which can avoid misjudgement caused by an abnormality of single source information. Firstly, the information uploaded from the remote terminal unit of the distribution automation system is used, and the user complaint information is converted into binary information. The fault information is formed based on the improved binary particle swarm optimization algorithm, and then the improved D-S evidence theory is used to fuse the positioning results of each fault information to obtain the final positioning result. The case study shows that the proposed method is effective and feasible, and can solve the problem when multi-source heterogeneous fault information has unrecognizable anomalies.

Site Selection and Capacity Determination of Multi-Types of Distributed Generation (DG) have a significant impact on the distribution network planning. Therefore, it is necessary to scientifically analyze the impact of the distributed generators on the distribution network, Considering the minimum sum of investment cost, network loss cost and power outage loss cost, the grid planning model is established by considering network constraints such as voltage constraint, line capacity constraint, power flow constraint and reverse power flow constraint.. The genetic algorithm is used to solve the optimal grid planning scheme for the distribution network with microgrid. Finally, the IEEE 14-bus Distribution Network is analyzed for the DG location and volume planning in Distribution Network to verify the validity and feasibility of the planning model.

This paper mainly presents a field-circuit coupled finite element model (FEM) of a large hydro-generator for the study of generator parameters. In the model, the two-dimensional (2D) moving electromagnetic field finite element model is coupled with the external circuit model, and some influencing factors are taken into account, such as saturation of iron-core, rotation of rotor, distribution of stator windings and end rings of damper bars, as well as end-impedance of stator and rotor windings. Based on this model, the parameters of the 1000MW hydro-generator are calculated, and the steady-state, transient, and sub-transient reactances are obtained. Furthermore, the calculation results are compared with the designed values, and some meaningful conclusions are reached. Finally, the influences of different loads and power factors on saturated synchronous reactance are discussed.

In order to improve the overall energy efficiency, one of the important trends in the field of energy is the construction of integrated energy systems. In the energy Internet, the comprehensive demand response makes use of the coupling and complementary relationship between different forms of energy, such as electricity and heat, and carries out the coordinated optimization of energy conversion equipment on the demand side to stimulate the flexibility of the comprehensive energy network, which is conducive to improving energy utilization efficiency and reducing energy supply and consumption cost. In this paper, considering the comprehensive demand side response of electricity and heat, an optimal configuration scheme of combined heat and power (CHP) unit is proposed. The scheme takes voltage amplitude, integrated network loss and economic cost as the comprehensive optimization objective. In order to effectively solve the above problems, this paper applies the sequence configuration strategy, adopts the direct power-thermal power flow method, weighted summation method and improved genetic algorithm to solve the above problems. Finally, the simulation of real medium voltage distribution network in Australia was carried out by MATLAB programming, which verified the rationality and superiority of the model.

Considering the demand of installing energy storage system by industrial users to reduce the basic electricity cost and increase the income of electricity sale, this paper proposes a detailed charging and discharging strategies calculation method to obtain the annual income. Based on the annual load historical data of industrial users, the charging and discharging modes and detailed strategies are determined according to the load characteristic and the electricity price period. Considering the influence of large and dense load on the peak load after peak shifting by storage system, a method of new peak load correction based on dichotomy iteration and backtracking mechanism is proposed. The case verification show that the monthly income is significantly affected by the industrial load characteristics. This method provides accurate income analysis for industrial users to ensure validity and economy of storage system investment.

Increment Capacity Analysis method has been widely concerned by experts and scholars because it can analyze the battery chemical reaction without destroying the physical structure of the battery. However the inevitable noise on the capacity increment curve brings huge damage to the analysis of the battery reaction process. In this paper, the influence of different voltage intervals on the ICA curve is analyzed firstly, then a certain voltage interval is selected, and the capacity increment curve is filtered by Gaussian process regression and wavelet transform. Compared with the original unfiltered ICA curve, the proposed method is verified feasible.

State of charge (SOC) is an important indicator for assessing the remaining capacity of the battery. An accurate SOC estimation is crucial for ensuring the safe operation of lithium batteries and preventing from over-charging or over-discharging in electric vehicle (EV) industry. However, to estimate an accurate capacity of SOC of the lithium batteries has become a major concern for the EV industry. In this paper, a recurrent nonlinear autoregressive external input neural network(NARXNN) model optimized by genetic algorithm(GA) is proposed to improve accuracy of SOC of lithium battery by finding the optimal value of input delays, feedback delays, and hidden layer neurons. The NARXNN based GA model is compared with the NARXNN in performance using statistical error values of mean absolute error and root mean square error are used to check the performance of the SOC estimation. The results show that the NARXNN based genetic algorithm outperforms NARXNN in estimating SOC with high accuracy.

Energy storage subverts the traditional concept of source-network-load, breaks the inherent property of power supply and consumption at the same time. Distributed energy storage plays an important role in the energy internet. The paper introduces the technical characteristics of distributed energy storage, builds typical application scenes under the energy internet environment. Given this background, two typical operation modes of customer-side distributed energy storage are proposed based on different operational objectives and constraints. After studying the basic strategy of the operating model and evaluating the distributed energy storage economy from the perspective of users and electricity retailers, it can be concluded that distributed energy storage is able to effectively improve system flexibility and energy utilization. Its economy is determined by various factors such as technical route, configuration capacity, and electricity price. A reasonable operation mode can promote the sustainable development of distributed energy storage.

Muslims are required to perform ablution before praying. This activity uses water, and can consume a huge amount of it when there are a lot of people who perform ablution at the same time. Conventional ablution taps are unable to control the usage of water. Usually, the tap is left running during this action. Therefore, a lot of fresh water unnecessarily flows to the drain. In order to reduce the usage of ablution water, this research developed a prototype of solar-powered, automatic water ablution tap. The system uses ultrasonic sensors to detect human presence and employs an Arduino microcontroller. It sends the "on" and "off" instructions to the relay to activate the solenoid valve to allow water flow. Water flow from the ablution tap can be more efficient with this system. The sensor detects the presence of human and works only when needed. So, the user does not need to touch the valve to activate water flow. This automatic control system can reduce the excessive water consumption when performing ablution. The testing of the system was conducted in a mosque in Indonesia. The experiment shows that the system is effective for detecting the presence of human in the range of maximum 50 cm above the tap. The used of ablution water is reduced significantly approximately 1900 cc compared to manual tap.

The aim of this research is to build a prototype of remote device that uses TCP/IP that could connect to a local network through a web server. The prototype has two features, firstly the prototype can toggle single specific lamp and turn off and turn on the lamps in an entire building. It is controlled through a web application which can also be operated through smartphones and computers. The experiment result shows that the prototype needed 500 seconds delay to activate the lamp and fan relays through the web server.

Peak load regulation and frequency regulation of electric power system are the main roles of Compressed Air Energy Storage(CAES). The static test method to active power compensation coefficient (APCC) has never been founded yet. Based on the operation character of CAES, the range of APCC has been given in this paper. This paper also introduced the static test system for APCC and the process of static test. In the end, the method of calculating for APCC has been established. With the static test, the APCC can be evaluated, which can make the grid more stable.

With the continuous progress of energy storage technology and the substantial reduction of cost, as well as the development of China's energy Internet, customer-side distributed energy storage has been applied more and more widely. Considering the customer-side distributed energy storage which takes the grid-connected "distributed solar + energy storage" as the main application mode, a distributed energy storage evaluation model based on double-granularity optimal operation strategy is proposed, which is built on life-cycle cost-benefit analysis model for customer-side distributed energy storage considering its operation optimization in advance. Taking large industrial and business consumers in one province in China as an example, the sensitivity analysis of customer-side distributed energy storage value is taken under different load characteristics, price policies, energy costs and energy storage technology characteristics, judging the customer-side distributed energy storage trends and potential of further development.

An energy storage system using a linear machine for lifting heavy mass to convert its potential energy to/from electricity has the following advantages 1) Environment friendliness; 2) Long life span; 3) Potential lower cost-to-life span ratio which tests human-beings patience to see. Such kind of system has rotor or mover and stator structure. For simplicity, the stator can take windings spreading from the bottom to top of interleaved stator structure with windings wound around it. The stator windings are formed by multiple strands of aluminium conductors in parallel to reduce ohmic losses, leading to higher efficiency. The rotor or mover is formed by multiple fundamental units which are reinforced by stainless steel or other reinforcement, each unit consisting of flat copper conductor sandwiched between magnetic materials through insulators. The copper conductor in each unit is joined at terminals either in series or in parallel. In this paper research is on the issues of having proper number of series and parallel circuits.

LiFePO₄ batteries have a variety of superior properties, such as higher power densities, higher capacities, longer lifetimes and better safety. For these reasons, LiFePO₄ batteries are used extensively in electric vehicles and energy storage devices. However, there is an issue with the battery capacity in that it begins to rapidly fade after a certain number of charge and discharge cycles under compound influence of temperature and discharging current, which may lead to safety concerns. Therefore, it is very important to investigate the characteristics (voltage, current and capacity) of LiFePO₄ batteries in relationship to the number of cycles and environmental temperature. In this paper, for the sake of high efficiency and safe operation of LiFePO₄ batteries, we propose a Back Propagation neural network (BPNN) model which estimates the state of health (SoH) of the battery, so that the accumulated error of the capacities under different operating environments can be corrected. The accuracy of the model was verified in an electric vehicle with an average error of only 1.56%. The results show that the proposed model is satisfactory.

With the increase of new energy permeability, photovoltaic power generation is widely used, but because of its own volatility and intermittent, it will lead to uncontrollable power generation and large fluctuation of grid-connected power.Hydrogen energy is a green and efficient way of energy storage.Hybrid energy storage system combined with super-capacitor can better realize photovoltaic grid-connected.This paper established a photo-hydrogen-supercapacitor hybrid energy storage system, contained electrolyzer, fuel cells and supercapacitor, and proposed a power coordination control strategy which ensure that the DC bus voltage is stable when PV is excessive or insufficient output or not worked on the rainy days or nights. Simulation proves the effectiveness of this system, and the maximum utilization of solar energy resources is realized.

Corrosion of grounding grids can affect the safe and reliable operation of power systems. In view of the corrosion problem of the grounding grid, this paper introduces the corrosion mechanism, which is chemical corrosion and electrochemical corrosion respectively. Then, three common grounding grid corrosion detection methods, such as electric network analysis method, electromagnetic field detection method and electrochemical method, are introduced. On this basis, the advantages and disadvantages of three methods are compared. Further prospects for the corrosion detection technology of the grounding grid are pointed out.

In order to improve the fault diagnosis accuracy of DC charging pile power devices, a fault diagnosis method based on wavelet packet analysis (WPA) and Elman neural network is proposed in this paper. This method sampled the output voltage signal of DC bus in fault state, decomposed the three-layer db10 wavelet packet and reconstructed the single branch, then calculated the characteristic energy spectrum of the fault signal using the signal in the frequency band, and identified it by Elman neural network. In order to test the diagnostic ability of the model, the PWM rectifier model of DC charging pile is used as an example to simulate and compare with the diagnostic results of standard BP neural network. The simulation results show that the fault diagnosis method based on WPA and Elman neural network has faster diagnosis speed, higher accuracy and stronger generalization ability.

The impulse magnetic current i_m(t) was generally neglected in conventional analysis of impulse current mutual inductor circuits. According to analytic results of the impulse magnetic current i_m(t), there were actually several positive components included in magnetic current i_m(t) and could not be ignored. When the impulse current mutual inductor circuits are operating stably, the impulse magnetic current i_m(t) is in proportion to duty cycle D. The waveforms of output voltage Vo(t) are also mainly depending on the impulse magnetic current i_m(t). Therefore, these relationships and curves could be used to instruct and verify the design and engineering application of the unidirectional and bi-directional impulse current mutual inductor circuits.

The ATP-EMTP program is used to calculate the power frequency overvoltage, open-phase power frequency resonant overvoltage, induced voltage and current, secondary arc current and recovery voltage, and switching overvoltage of 750kV four-circuit transmission line on the same tower. The study reveals that the configuration of four circuits on the same tower has little influence on the power frequency and switching overvoltage, but greatly influences the secondary arc current and recovery voltage, and induced voltage and current. Therefore, measures like installing high-voltage shunt reactor and neutral grounding reactor and line transposition are required. Also, the induced voltage and current ratings of earthing switch are proposed.

The hybrid multi-terminal direct current (MTDC) system, with the economic superiority of LCCs and technical flexibility of VSCs, is one of the development directions of future DC transmission technology. This paper introduces the development of Hybrid-MTDC transmission projects as well as the related publications especially on fault control strategies. A ring hybrid three-terminal DC transmission system was built on PSCAD/EMTDC to simulate pole-to-pole short-circuit faults at different locations. The fault development process and fault characteristics on DC lines are analysed and summarized, which aims at providing the theoretical basis for the protection principles of hybrid MTDC systems.

The very fast transient overvoltage (VFTO) is changed when stepped controllable shunt reactor (SCSR) is installed in substation, this paper simulates and analyzes the closing sequence of the disconnector (DS) and voltage transformer (PT) installation location's influence on VFTO with Dommel transmission line, and establishes the VFTO suppression equivalent impedance model in frequency domain, and analyzes the effect of various measures to suppress VFTO time-frequency amplitude. The results show that the VFTO dominant frequency and the corresponding amplitude can be reduced by reasonable choice of DS closing sequence and PT installation site. Compared to the closing resistor, ferrite has advantages in suppressing VFTO. The peak of VFTO increases first then decreases with the increase of the length of the ferrite.

In order to ensure the stable operation of the power system and solve the influence of uncertain factors such as traveling wave velocity on the transmission line, this paper proposes a new fault location method that is not affected by the wave velocity for the T-type transmission line. The method first determines the branch where the fault is located, and the faulty branch can be determined only by the time when the initial traveling wave of the fault voltage reaches the three ends of the T-type transmission line and the length of the three branch lines. Then, the location of the fault point is determined according to the time when the initial voltage traveling wave reaches the three-terminal of T-type transmission line. Finally, simulation is conducted in matlab/simulink. The simulation results show that this method can accurately locate the fault point.

This paper investigates the impact of opportunistic maintenance strategy on power equipment maintenance scheduling under economic dependence. The model focuses on power equipment with two types of failures: random failure and deterioration failure. Unlike previous research which didn't consider opportunistic maintenance between different failures modes, opportunistic maintenance strategy is proposed in this paper. In the opportunistic maintenance strategy, whenever random failure occurs, decision has to be made on whether deterioration failure is preventively maintained based on the degree of equipment deterioration and economic dependence. Firstly, Markov process is used to describe equipment state-space diagram. And then, in order to determine the optimal inspection rate, preventive maintenance threshold and opportunistic maintenance threshold of power equipment, the analytical expressions of inspection cost, maintenance cost, repair cost and outage cost are quantified. Finally, the total cost is minimized to get the optimal maintenance strategy. Case studies demonstrate the feasibility of the proposed model.

The stable operation of the flexible AC-DC hybrid distribution network is inseparable from the configuration of the relay protection device, while the fault analysis and simulation research is the basis for the protection scheme selection. This paper introduces the current situation of fault analysis and protection research of flexible AC-DC Hybrid distribution network, and set up a model of radiated flexible AC-DC hybrid distribution network on PSCAD/EMTDC platform, then deeply analyzed the grounding fault of VSC single-pole short circuit of DC side. According to the simulation results, the trend and characteristics of the transient state after the fault are studied, which lays a foundation for the research of the subsequent relay protection method and the configuration of the protection device.

In order to solve problems that the low coincidence success rate of the automatic reclosure of distribution network and short-circuit current has a large impact on the system when it coincides with the permanent fault, a shunt resistance type of adaptive reclosing switch is proposed. In order to improve the success rate of reconfiguration of the distribution network. By selecting the appropriate shunt resistance, the switch can not only suppress the magnetizing inrush current, limit the short-circuit current, reduce the system impact, but also use the current characteristics flowing through the shunt resistance to determine whether there is a permanent fault in the downstream, and realize the adaptive reclosing. The shunt resistance type adaptive reclosing switch can be separately applied to the power distribution switch to replace the original reclosing mode, and as a switch with protection function, the safety of the fault handling process is improved.

The paper proposes a designed scheme for the fault detection system of low voltage cable breakage in power system. By analyzing the characteristics of low voltage power line communication channel, establishing the channel characteristic model and comparing the measurement data with the simulation model, the author summarizes the impedance characteristics, noise characteristics and attenuation characteristics. It can be concluded that the suitable frequency range for communication is between 120kHz and 20kHz. The signal modulation method is studied, that the spread spectrum modulation is a preferred method. It also shows good results in the simulation. The object testing is done. The device and test method selected by author can be used to realize the early warning function of the power system low-voltage cable disconnection fault.

In order to intensively study the exterior transient electromagnetic interference characteristics caused by disconnector operation in Gas Insulated Switchgear, experimental research of exterior transient electromagnetic interference under switching conditions is performed in this paper. Based on 330kV GIS test platform, with the method of resistive impedance divider, TEV is measured with Pintech P6039A high-voltage probe and Yokogawa DLM2054 oscilloscope by using resistor voltage divider GIS exterior radiation electromagnetic circuit is also established using antenna theories, biconical antenna and spectrum analyzer etc. The exterior transient electromagnetic interference waveform and characteristics are precisely measured. By the contrast analysis of TEV and radiation electromagnetic waveforms, results can be summarized as followed: ① The TEV waveform caused by opening and closing of disconnecting switch is front sparse and rear dense, and its amplitude is low at the fore and high over the back; The electric field strength is weaker compared to the electromagnetic compatibility of normal substation.

In order to solve the problem of detecting the fault indicator in the field, a design scheme of the portable fault indicator detector based on the Internet of Things is proposed. Firstly, the overall architecture of portable fault indicator detector based on Internet of Things is designed. Secondly, the system architecture of portable fault indicator detector is designed from two parts and seven aspects. Then, the hardware architecture of UPS power module, AC power amplifier module and human-computer interaction module is designed in detail. Finally, the main functions and detection methods of the portable fault indicator are discussed. The case analysis shows that the portable fault indicator detector based on the Internet of Things has greatly improved the time, manpower and cost of detection compared with traditional detection methods, and can conveniently meet the needs of on-site inspection personnel.

In order to solve the problem of status detection evaluation of field operation fault indicator, a status detection evaluation method of distribution network fault indicator based on artificial intelligence is proposed. Firstly, the fault indicator status detection evaluation model is established, and the result information of fault indicator detection using portable detector is described by fault indicator status detection information matrix. Secondly, based on the principle of "3 selection 2", the fault indicator status detection comprehensive result table is established. Then, the same factory fault indicator status detection evaluation matrix and the fault indicator single state detection comprehensive evaluation matrix are established to evaluate the 10 functional detection results of a single fault indicator of a manufacturer. Secondly, the fault indicator sub-detection comprehensive evaluation matrix is established to describe the evaluation results of all fault indicators in the same plant on different sub-function detection. Finally, the comprehensive evaluation results of all fault indicator detection in the same plant are evaluated by means of the average method. The example analysis shows that the method described in this paper can evaluate the status detection results of fault indicators from three aspects: individual, sub-item and comprehensive, which has good practical significance.

The paper proposes a new location method of faulty segment for hybrid transmission lines combined with overhead line and cable. Conventional location method of faulty segment identify faulty segment through position calculation of fault point. However, affected by error, the fault at cable-overhead line joint is hard to be identified. In this approach, faulty segment is identified through characteristics comparison of transient travelling wave under different condition. Compared with situation that fault occurs on overhead line, if fault occurs in cable, there is an additional impedance discontinuity in cable. Thus, the amplitude and wave of various reflected wave will change significantly. The proposed method extracts various reflected waves based on time windows and polarity. It makes use of the relative amplitude and time difference between first travelling wave and secondary reflected wave of cable-overhead line joint as criterion of faulty segment location. To verify its effectiveness, fault simulations based on EMTDC are performed; the simulation results reveal that the proposed method can correctly identify the faulty segment for hybrid transmission lines.

In order to find the reason of the high voltage circuit breaker rejection quickly, an fault diagnosis method based on reasoning chain and Bayesian network (BN) is presented in the paper. Firstly, the concept of event set is introduced. A fault symptom set is constructed based on the measured circuit breaker characteristic parameters and warning signals. And the direct cause of circuit breaker failure, such as a part of the circuit breaker components or mechanism failure constitute the fault cause set. After that, when the high voltage circuit breaker fails, a subset of fault symptoms and fault causes is obtained according to the information. Then an reasoning chain is constructed according to the causal relationship between the two. Finally, a corresponding Bayesian network model for reasoning chain is built. The probability of fault causes is obtained by Bayesian backward reasoning, so as to realize the rapid analysis of circuit breaker faults. And the effectiveness of the method is verified by the result of practical fault diagnosis examples.

The maintenance and self-healing of circuit breakers are very difficult when the fault diagnosis results of circuit breakers cannot cover all kinds of fault causes. This paper proposes a method for comprehensively diagnosing circuit breaker faults. The method simulates the action process of circuit breakers based on weighted fuzzy Petri nets and makes it feasible to infer circuit breaker fault causes from different aspects. The model shows the action sequence of the circuit breaker by associating the control mechanism, the operating mechanism, the transmission mechanism and the contact part of the circuit breaker, and each part of it is described with the corresponding abnormal signals of the circuit breaker stored in the substation end. Specific fault reasons of the circuit breaker can be inferred by considering the action sequence and the relationship between the abnormal information and fault causes. The results for some test cases show that this method can obtain the diagnosis results covering various possible fault causes.

Many typical non lightning failures of transmission lines are caused by foreign matter, such as bird streamer, floating objects, branches and so on. In this paper, 110kV composite insulators are taken as the research object. First, the mechanism of flashover caused by foreign matter is analysed theoretically, and then a three-dimensional model of composite insulators is built by using the Maxwell simulation software. Electric field and potential changes of the composite insulator in the presence of different foreign matter are studied, and the flashover mechanism and related influencing factors are analysed. Based on this, through a large number of simulation calculations, the area of 110kV composite insulator caused by foreign matter flashover is finally given, which provides guidance for the typical non-lightning fault of 110kV line protection.

Switched reluctance motors (SRM) are the core components of household appliances, which directly affect the performance and quality of household appliances. We have studied the application of switched reluctance motors in the home appliance industry. The 12/8-pole three-phase switched reluctance motor with a new rotor structure was proposed for the performance of SRM and the performance is simulated by MATLAB tools. Besides, the control principle and the operating equations of the switched reluctance motor are also introduced and deduced in detail. For the further work, although the 12/8 pole switched reluctance motor can effectively reduce the torque ripple, it cannot be completely eliminated. Therefore, the next step should continue to explore ways to reduce torque ripple.

Large-scale integration of intermittent energy has brought many problems to active power dispatching of the power grid, which will not only increase the operation cost, but also increase the operation risk. This paper developed a multi-time scale scheduling strategy, integrated day-ahead scheduling, intra-day dispatching and automatic generation control (AGC) system, in order to ensure the safe and stable operation of power grid. The strategy aims to minimize the sum of operating costs of power system, and sets six constraints such as power flow constraint, to analyse and optimize the dispatching process of power systems. After simulation and analysis by Particle Swarm Optimization (PSO) algorithm, the results show that the strategy has a significant optimization on the power system with intermittent energy.

In order to solve the problem of online monitoring and early warning evaluation of intelligent distribution station, an operation situation assessment of intelligent distribution station based on internet of things is proposed. A multi-source data information matrix is established for the distribution station, and describes the temperature information, humidity information, water intrusion information, smoke information, switch telemetry information, and switch remote control information of the intelligent distribution station within a period of time before the current time. The distribution station multi-source information matrix is quantitatively evaluated through the distribution station multi-source evaluation matrix. Then, the distribution station multi-source evaluation matrix is quantitatively integrated for each column to generate a distribution station multi-source single evaluation matrix. Finally, based on the weighted average method, the distribution station multi-source single evaluation matrix is integrated to generate the distribution station operation situation evaluation index to describe the overall operation situation assessment of intelligent distribution station. The feasibility of the proposed method is verified by the example analysis, which can meet the actual needs of the field project.

This paper presents a simplified regression model for building dynamic DR processes based on the mechanism model to facilitate the timely analysis, prediction and optimization of aggregation DR characteristics of a large-scale diversified building load. First, numerous simulations based on the mechanism model are performed to obtain sample data of building DR under different external conditions. Second, the key factors influencing the dynamic demand response process of a building—namely, the climbing period, stable response period and recovery period—are analyzed. Finally, this paper analyzes the simulation error and calculation efficiency of the proposed simplified regression model. Furthermore, the calculation speed is sufficiently fast to meet the requirements of real-time scheduling.

With the advent of the era of power big data, power companies can easily access more and more user power data, but they are not making full use of such massive datasets to reflect their value. Due to the huge amount of data collected by the power system, the total amount of abnormal data collected cannot be ignored. These abnormal data cause great interference to subsequent data analysis and maintenance; It's also important to find how to identify user's abnormal behaviour based on the power dataset. In this paper, a smart operation and maintenance system based on deep learning is proposed. Based on the composite mathematical statistics method, the data is efficiently reviewed and cleaned. The isolated forest algorithm is used to quickly identify the users with abnormal power consumption and GAN is used to help evaluate this model. This system can help power companies efficiently complete data review and anomaly identification, and can integrate data information from multiple dimensions to guide the actual maintenance and verification.

The development of mobile technology and the Internet has brought many potential threats while bringing convenience to users. Aiming at the leakage of private data and transaction sensitive information in mobile trading market, we study the multi-security authentication support technology of mobile transaction mobile application, and analyse the common mobile application content, document protection technology and mobile signature protection technology. Based on the identity authentication technology of mobile application and the security considerations of members and transaction data in the power trading market, an identity authentication technology using SMS verification code, mobile phone shield, face recognition and fingerprint identification is proposed to protect the mobile transaction mobile application transaction. Anti-leakage of market member privacy data and transaction-sensitive information. In order to verify the effectiveness of the proposed scheme, we carry out the simulation experiment. The experimental results show that the proposed scheme can effectively protect the privacy of users.

We achieve an integration of the power trading business with new technologies by rationalizing the convergence path of new technologies and transaction services. To realize the personalized customization of electricity market information services and form automated and flexible expansion capabilities, we build a new architecture of cloud-based power trading platform which establishes and applies power market big data resources, improving platform capacity and business application level. The architecture built in the article achieves the decentralization, real-time processing, high concurrency, high availability, easy maintenance, and convenience and efficiency of the power trading platform.

Fine-grained power data are used to characterize user's behavior in smart grid, Non-intrusive load monitoring can effectively separate the load of a single electrical appliance from the whole energy consumption of a dwelling, which is beneficial to fully exploit the load potential. In this paper, considering the relationship on usage habits among electrical appliances, the characteristics of energy consumption, we propose a multi-objective modeling method based on deep learning. The multi-objective model is constructed by CNN and LSTM, and the neural network is collaboratively optimized by multi-objective outputs. The experimental results show that the multi-objective model performs better than the other models on the five appliances, reducing the absolute error to less than 10 and the total error of the standardized signal to less than 0.1.

Aiming at the shortcomings of traditional MPPT method, such as slow tracking speed and oscillation at maximum power point, this paper combines neural network with dichotomy to propose a new maximum power point tracking method for photovoltaic power generation system. And the traditional neural network uses the gradient descent method to solve the problem that the parameters are easy to enter the local optimal solution. In this paper, the improved differential evolution method is used to solve the global optimal solution. The neural network is used to track the vicinity of the maximum power point, and then the dichotomy is used to further approach the maximum power point. The simulation results show that compared with the traditional MPPT method, BP neural network and dichotomy can track the maximum power point faster, avoid the oscillation phenomenon, and have faster tracking speed and higher tracking accuracy.

Virtual reality technology has been widely used by constructing a virtual space to simulate and restore the real world. The system uses 3ds MAX and Unity3D software to establish a 500kV substation virtual simulation system. The system completely establishes the 3D models of primary and secondary equipment of 500kV substations, and truly restores the overall layout of the substations. At the same time, the Unity3D engine, VR technology and interactive equipment are used at the same time to make this system able to provide trainees with an immersive training experience, which is more realistic than the application over the same period. The system completes the realization of substation training, station roaming and fault simulation functions, including substation equipment technical parameter display and synchronous voice introduction, interface design, basic operation, and fault phenomenon simulation; the infrastructure of the system is developed well and has strong expandability, which lays a foundation for subsequent function development. This system satisfies the substation training needs and can be used for related staff training of substations and to help students in electrical major to gain cognitive learning.

With the development of scale of the power grid, the phenomenon that the construction personnel across the safety fence at will occurs frequently, which brings great hidden trouble to the safety production. In allusion to the existing problem of the safety fence without monitoring and alarm function, in which the principle of inter-frame difference method is used to screen out the illegal workers, making accurate diagnosis of the illegal behavior, and sending warning information to remind the illegal workers by using the method of trajectory tracking of moving object to filter out the random disturbance signal, so as to ensure the safety of the construction.

Overvoltage is one of the important factors that cause line tripping and equipment damage. Accurate monitoring of transmission line overvoltage is of great significance for safe operation of power grid. In this paper, a transmission line overvoltage sensor based on the principle of coupled capacitance partial voltage is designed. The high voltage arm capacitance of the sensor is the stray capacitance between the sensor metal sheet and the earth, and the low pressure arm capacitance is the coupling capacitance between the sensor metal sheet and the wire. At first, the structure characteristics and sensor principle of the sensor are described, and the parameters of the sensor are calculated. The results show that the sensor has high detection accuracy and can realize overvoltage monitoring of transmission lines.

With the replacement of power sources of traditional vehicles, the penetration of EVs in the world is increasing year by year. When large-scale EVs are connected to the power grid, it will affect the structure and power flow of the grid. This paper simulates the vehicle route in the planning area, proposes a method to predict the probability distribution method for the users to choose the specific route based on the Markov process theory and the traffic network database. Refer to the habits and charging preferences of EV users, taking private EVs as the research object, Monte Carlo simulation is used to predict the charging demand generated by EVs in the function area and important road nodes in the planned area. In view of the difference of peak price and valley price, considering the low valley-time price, the probability of load transfer is large. Changing the discharge strategy to realize the peak load shifting in V2V mode.

Site Microturbine Generation (MTG) is a distributed Generation technology with wide application prospect in micro grid. This paper introduces the single-axis micro-gas turbine power generation system in detail and studies its operation and control in micro-grid. In this paper, PSCAD/EMTDC simulation software is used to simulate the load tracking ability of the micro-turbine power generation system under the island operation mode, and the ability of the micro-turbine power generation system to stabilize the voltage and frequency under the two modes of island and grid connection. The simulation results verify the correctness of the micro gas turbine model and its flexible adjustment control mode according to the needs of micro grid operation, which has good operation characteristics.

The submarine cable salvage robot needs energy storage device as power supply or backup power supply when working underwater. The optimal control strategy of load distribution can realize the reasonable distribution of electric load among multiple energy storage devices according to the different residual capacity of energy storage devices, thus improving the energy utilization efficiency of energy storage devices and prolonging the operation time of salvage robots.

In the design of submarine cable salvage robot, considering the limitations of weight, space, cost and many other factors, the robot can only carry energy storage devices with limited capacity. In the process of dynamic regulation, current sharing technology is used to ensure safe operation. In the steady state operation, through the optimization of load distribution scheme, the optimal control of overall efficiency of energy storage device can be achieved, the utilization efficiency of storage energy can be improved, and the overall operation performance of electrical system can be improved

In order to quantitatively evaluate the basic capabilities of smart meter enterprises on National Quality Infrastructure (NQI) and continuously improve the quality level of smart meter enterprises, this paper, profited from China's NQI capability index system and the Delphi method, with representiveness of indicators as the starting point, and based on repeated screening and expert demonstration, chooses the most representative indicators devised for NQI factors such as measurement, standardization, certification & accreditation, inspection & testing and quality management in the production of smart meters, and constructs an indicator system applied to evaluate the basic capabilities of smart meter enterprises on NQI, which includes 5 first-level indicators, 8 second-level indicators and 30 basic indicators. With construction of this system, we can quantitatively evaluate the basic quality and technology capabilities of smart meter manufacturers and continuously improve deficiencies of enterprises on their NQI. And, the State Grid can also apply this system as a technical specification to evaluate the quality level of smart meter enterprises.

The corona discharge pulse current has double exponential distribution characteristics. On this basis, the electromagnetic radiation model of corona discharge is established by using the theory of electric dipole. The corona discharge characteristics are analysed and compared with the measured results of 1000kV UHV ac transmission line. The results show that the electromagnetic field strength increases first and then decreases with time, and at the same time, the electromagnetic field strength decreases exponentially with distance. The simulated and predicted corona discharge radiation characteristics have the same variation law as the measured data, which verifies the correctness of the model.

In order to improve the accuracy and rapidity of the disturbance source location, a new method based on variational mode decomposition (VMD) for forced power oscillation disturbance source location is proposed. Using the active power and frequency of the transient phase of an oscillation, the dominant mode of electrical components is extracted by VMD. Then, the oscillation energy using the variation is calculated to achieve the disturbance source location. Taking the forced power oscillation accident caused by too strong primary frequency modulation as an example, the effectiveness and feasibility of the proposed method is verified.

In this paper, the MCR with distributed magnetic valves is proposed. The magnetic valve is equally distributed in iron core, which is piled up by silicon-steel sheets and epoxy sheets. Field-circuit coupled simulation model is established in ANSYS software. The wave forms of electrical state variables, magnetic flux density distribution and iron core losses are acquired. The comparison with the MCRs with a single-stage magnetic valves and multiple-stage magnetic valves demonstrates the advantage of proposed magnetic valve structure.

Accurate measurement and localization of Partial Discharge (PD) is necessary for safe and stable operation of power equipment. Recently, the method based on the amplitude strength of Ultra High Frequency (UHF) signals has been proposed that bearing a low hardware requirement compared to time-difference-based methods. However, the widely studied fingerprinting based positioning technology is hard to deployed due to a heavy burden of fingerprinting map building. Therefore, this paper proposes an amplitude strength attenuation model and localization equation is proposed for PD localization in air-insulated substation. The field test is performed and the results show that the mean PD source localization error is 2.51 meters which is enough to distinguish the power equipment that having insulation deterioration.

In recent years, two series reactor faults occurred when a 35kV shunt capacitor bank was cut by a circuit breaker in a 500kV substation in Shenzhen. The reason is analyzed that the large inrush current and overvoltage generated during the switching process caused interturn short circuit fault of the reactor, which seriously threatens the safe operation of the system. To avoid such faults, intelligent phase-controlled short-circuit breakers were used to suppress the closing inrush current and reduce the probability of reignition. To verify the effectiveness of the technology, this paper introduces the causes of switching inrush current and over-voltage and the principle of phase-controlled suppression technology, and then applies the technology to a 500kV substation in Shenzhen. Multiple switching tests are carried out on the intelligent and ordinary circuit breakers respectively. The results show that the maximum inrush current generated by the ordinary circuit breaker is 4.2p.u., and the overvoltage is 1.81p.u. While the maximum inrush current of the intelligent phase-controlled circuit breaker is 2.3p.u., and the overvoltage is 1.4p.u. The results confirm that the application of the intelligent phase-controlled switching technology can suppress the inrush current and overvoltage, thus fundamentally improving the reactive switching efficiency and system safety.

The characteristic of traveling wave transmission has great influence on the location precision of the fault point. In order to accurately evaluate the transmission and attenuation characteristic of actual traveling wave on transmission lines, a typical asymmetric arrangement 110kV transmission line is selected as the research object. First, the parameters of the transmission line are calculated, and the traveling wave decoupling algorithm is derived. Then, the traveling wave current collected by the distributed traveling wave monitoring system on the line is analyzed. The results show that for a short distance asymmetric 110kV line, it can be decoupled by the conventional decoupling balance line method, and the coupling component ratio is less than 2% after decoupling. With the increase of transmission distance, the attenuation degree of traveling wave increases. When the transmission distance is 60km, the attenuation of line mode is 21.2% and the zero mode attenuation is 50.4%.

In Zhenhai-Zhoushan transmission project, 500kV XLPE submarine cable lines are used for the first time in the world. Using electromagnetic transient simulation program(EMTP), electromagnetic transient problems in this project are investigated including electrical parameter of submarine cable lines, power frequency overvoltages, secondary-arc currents and recovery voltages during the single-phase reclosing, power frequency resonance overvoltages, induced voltages and induced currents, switching surges and so on. On the basis, the recommended configuration scheme of HV shunt reactors and neutral reactors is proposed. In addition, it is suggested to install closing resistors of 400ohm on both sides of line breakers in order to restrict switching overvoltages and ensure safe operation of submarine cable lines.

Flashover fault is an important cause of trip or even outage of transmission lines. In order to reduce the occurrence of tree flashover failure and strengthen the management of tree growth in the transmission line corridor, it is necessary to study electric field and potential distribution characteristics of trees below transmission lines. Firstly, the influence of tree dielectric constant and conductivity on 3D modelling is analysed. Then the actual 3D simulation model is established. The spatial electric field and potential variation of trees with different shape crowns and different heights and horizontal distances are studied. The starting field strength of flow is used as the gap breakdown criterion, and the critical breakdown distance under different power supply phase angles is calculated. Conclusion shows that the critical distance of tree flashover of 500kV transmission line is 1.76m. In practical applications, trees should be avoided too close to the wire.

Common faults on transmission lines, such as insulator pollution flashover, trees flashover, string breakage failure of insulator will undergo a period of discharge before the occurrence of flashover, which is called insulation defect discharge. In this paper, the process of discharge such as floating discharge, insulator pollution discharge and tree discharge is simulated in the laboratory environment and the high frequency current waveform is monitored. The results show that insulation defect discharge will maintain a long period of time and will not immediately form a flashover fault, in addition, a great deal of high frequency discharge current pulses will be generated during this period. The discharge characteristics and the discharge pulses generated by different type of insulation defect discharge are quite different. Frequency of floating discharge current waveform are very high, while the pulse cluster of pollution discharge is dense, and the current waveform generated by tree discharge has notable dispersity. With the degree of discharge increasing, the parameters such as pulse repetition rate and discharge amount are gradually increasing.

Under the increasingly stringent situation of environmental protection management, it is necessary to research the distribution law of power frequency electric field around Ultra-High Voltage (UHV) AC transmission lines to provide technical basis for the design of transmission lines and the environmental impact assessment. Firstly the basic principle of equivalent charge method and its mathematical model are introduced in this paper. Then it is researched how to use equivalent charge method to analyze the electric field near the transmission lines. Based on the three-phase double-circuit overhead transmission line model, the influences of several factors on the power frequency electric field have been analyzed. These factors include the conductor-to-ground height, the phase sequence arrangement, the number of split conductors and the split spacing. Finally the frequency electric field of parallel UHV AC transmission lines is discussed. The results can provide reference for engineering design of UHV AC transmission lines.

Fractional slot concentrated winding interior permanent magnet synchronous motor (PMSM) has the advantages of high torque density, high efficiency and simple manufacture, which has been widely used in electric vehicles. In this paper, a fractional slot concentrated winding interior permanent magnet synchronous motor (PMSM) with "▽" shape rotor is proposed. This paper focuses on how to reduce the torque ripple of the motor. The permanent magnet angle and eccentric length are optimized to maximize the fundamental air-gap flux density and minimize its torque ripple. The cogging torque, torque ripple, iron loss and efficiency of the motor are analyzed. Finally, the finite element results verify the effectiveness of the optimization.

The 300 MW unit of a power plant is resistant to fuel, and its color is reddish brown. The acid value and resistivity are in line with the standard requirements. However, a large amount of sludge appears in the same grade of oil, causing the filter to be blocked and unable to supply oil. After the oil is filtered by the online oil filtering device, the degraded anti-fuel oil and the new oil are mixed and there is still sludge. In order to solve this problem, the components in the anti-fuel oil were tested and the acid value, moisture, resistivity, particle size and sludge precipitation test were tested. The cause of the sludge in the mixed oil was found and the treatment method was found. The oil samples were adsorbed by diatomaceous earth, activated clay and strong polar silica-alumina, and the parameters were analyzed after treatment. It was found that both activated clay and polar silica-alumina adsorbent have better purification functions, but the polar silica-alumina adsorbent is better and effectively solves the problem of fuel resistance degradation.

The analysis of current transfer characteristics of hybrid DC circuit breakers is of great significance for improving their breaking capacity and implementing control strategies. This paper analyzes the principle of hybrid DC circuit breakers. The hybrid circuit breaker simulation model is built based on the Mayr arc model in Matlab/Simulink using IGBT, RCD snubber circuit and arrester model. The current simulation waveforms under different external circuit parameters and transfer branch parameters with a voltage of 400V and breaking fault current less than 200A are mainly studied. Through the analysis of the current transfer characteristics, a series of theoretically supported breaking characteristics are obtained, which provide a reasonable and effective reference for the fast and reliable breaking of DC micro-grid hybrid circuit breaker.

In order to analyse the over-modulation technique impact on the micro-source inverter (MSI) series micro grids (SMGs) output voltage, firstly Double Fourier method applied to derive the single inverter output voltage characteristics under over-modulation condition; Secondly, based on the characteristics of the MSI series micro-grids, a new formula of the system output voltage is derived. Thirdly, the impact on the system output voltage fundamental component and harmonic component is analysed in detail, the results show that the output voltage fundamental component increases with the increasing modulation while keeps constant after a certain over-modulation depth. Finally, a simulation was carried out and the simulation verified the theoretical analysis.

Aiming at the shortcomings of single-protection circuit in the low-voltage ride-through (LVRT) process of doubly-fed induction generators (DFIG), this paper proposes an integrated protection circuit strategy for LVRT of DFIG based super-capacitor(SC). The integrated protection circuit includes a Crowbar circuit, a rotor series dynamic resistance (SDR) and SC. By adopting different protection circuits in different situations and time divisions, the LVRT capability of the DFIG is comprehensively improved, and the transient current of the rotor current during the protection circuit input is analyzed in each case. Finally, the proposed integrated protection circuit strategy is compared with the traditional single Crowbar circuit and single SDR on the simulation platform MATLAB/Simulink. The simulation results demonstrate the effectiveness of the proposed integrated protection circuit strategy.

This paper proposes the design of a closed-loop vector control structure based on Recurrent Functional Link based Elman Neural Network (RFLENN) for a Static Synchronous Series Compensator (SSSC), linking to a Seashore Wave Energy System (SWES) driven Doubly-Fed Induction Generator (DFIG) is connected. A RFLENN controller for a SSSC in order to reduce the power fluctuations, voltage support and damping for a hybrid power system. The proposed RFLENN is a functional link-based recurrent Elman Neural Network. Analysis of the performance of the proposed controller shows that it can achieve better damping characteristics. The internal power fluctuations to the power system can effectively stabilize the network under unstable conditions. This paper presents a closed-loop vector control structure based on RFLENN for a grid-connected SWES driven DFIG. This paper presents the transient stability improvement and power-flow control results of a DFIG-based SWES connected to a SSSC connected in series with one of two parallel transmission lines.

In order to keep frequency stable after UHV DC block fault, demand side resources are needed. Among these, frequency-based load can automatically monitor the frequency change without affecting the user's power consumption experience and can quickly adjust the operating parameters to reduce its own power consumption. Thus, frequency-based load can play a role similar to the primary frequency regulation. In this paper, several physical models of typical frequency-based loads were established and the frequency regulation characteristics are analyzed. Based on this, a decentralized strategy of frequency-based load was proposed. The simulation results show that the grouping decentralized strategy can effectively avoid the "over-control" or "under-control" phenomenon, which helps to quickly maintain the power balance and frequency stability of the grid.

Recent years, the wide application of intelligent energy metering in smart grid leads to the increasing demand for intelligent energy meters. Automated, industrialized large-scale verification systems are widely constructed in important local power supply companies to increase the intelligent energy meter verification ability. The optimization scheduling of verification system utilizing the advanced optimization scheduling method is a necessity to improve verification efficiency. With this regard, considering the block of multi-function verification device caused by unqualified verification result, a model based on the robust optimization method is proposed to minimize the total verification time and improve the verification work efficiency. Deterministic transformation is illustrated to solve the model. The accuracy and effectiveness of the proposed optimization model are verified in simulation results and actual operation.

The reliability of DC arresters is one of the basis of safe operation for HVDC transimission system, the aging test is the main measure to obtain the reliability of arresters, and therefore, is of great importance. The test voltage with ideal waveforms had not been produced before by any of the test equipment when it is loaded. The paper introduces a method to produce the aging test ripple voltage waveforms of 6 pulses and 12 pulses converter which fully considers the influence of trigger angle and commutation angle. The paper designed a kind of ripple voltage power source which can series, and produce the ripple waveform of any trigger angle and commutation angle, the output voltage of one module is up to 1kV. The device went through 1000 hours of testing, and commutation process can be seen in the oscillograph clearly, including stable commutation overshoot. The oscillograph also show that the fundamental frequency of the waveform is stable, and waveform distortion is small and can be ignored. The output voltage meets the requirements of aging test for various types of DC arresters.

With the rapid development of electric vehicles, increasing electric vehicle charging load will have extensive impacts on the power grid. This paper innovatively analyzed the impact of charging load on the urban power grid by taking the power grid of a large city as an example. Firstly, the scale of electric vehicles is predicted. Secondly, considering the travelling characteristics of electric vehicles, the charging load characteristics of electric vehicles in different functional areas of the city were analyzed. Finally, the impact of unordered charging of electric vehicles on urban power grid is quantitatively analyzed from four aspects, including load structure, on-peak and off-peak difference of system, distribution network utilization rate, charging facilities and supporting network construction. Electric vehicle charging will change the load structure of the power grid, reduce the utilization rate of distribution network and investment efficiency, increase the on-peak and off-peak difference of system etc.

The principal contradiction facing Chinese society has evolved. What we now face is the contradiction between unbalanced and inadequate development and the people's ever-growing needs for a better life. As power grids play a significant role in energy resource distribution and utilization, the quality of power grid development is the foundation of healthy social and economic development of China. This paper analyses the unbalanced and inadequate development of power grids. Firstly, current situation and problems of power grid development are analysed. Secondly, an evaluation system of unbalanced and inadequate development of power grids is built to quantitatively assess the development of power grids. The unbalanced development index system is composed of secondary indicators of unbalanced urban and rural grid development, unbalanced regional grid development and unbalanced load development. The inadequate development index system is divided into scale indicators, quality indicators, automation indicators and management indicators. Each secondary indicator is then further detailed into tertiary indicators. Then, a case study of provincial power grid is applied to prove the effectiveness of the proposed index system. Study results highlight some problems, for example, unbalanced transmission and distribution grid development, unbalanced urban and rural grid development, unbalanced regional grid development, inadequate distribution grid development, inadequate automatization etc. Lastly, future improvements and measures are pointed out.

The ground current of HVDC transmission will cause DC bias of transformer in AC system. In order to master the influence of typical AC grid parameters on DC current distribution, a direct field-circuit coupling model of AC and DC power grid is established, and the evaluation parameters of DC current distribution are proposed. The influence of various factors such as the grid density, transformer and transmission line branch resistance, tower-ground wire system on DC current distribution in AC grid are quantitatively analyzed by grid examples. The results show that the denser the grid of a certain voltage level, and the smaller the circuit resistance of transformer and transmission line branch of a voltage level, the larger the DC current of the voltage level and the total DC current of the AC grid. When considering the tower-ground wire system, the DC current entering the AC power grid increases, and the smaller the wire DC resistance and the tower grounding resistance, the more DC current increases. In a line, the tower with the largest grounding current generally appears in the tower 1-4# near the substation with the larger current amplitude. In the calculation process of DC current distribution in large AC grid, ignoring the mutual resistance effect between substations will make the DC current of the AC grid larger, so it is not advisable to neglect the mutual resistance between substations in calculation.

As renewable power generation directly affects the customers' traditional electricity behavior and then offsets the power load, this paper proposes a load curve modeling method for renewable power customers based on the behavior analysis. Firstly, customers' active behavior is represented by the quantity of active customer households. Based on the analysis of customer behaviors, a modeling method for the quantity of active customer households is proposed based on Markov Chain Monte Carlo method. Then, with the inputs as the quantity of active customer households and time of photovoltaic power generation, an inference model based on fuzzy logic is proposed to get the quantity of customer household starting electrical appliances. By combing the average usage time of electrical appliances, load characteristics are analyzed based on usage state of electrical appliance of distributed power customers. Finally, the simulation results verify the effectiveness of the proposed method.

CAN communication is a relatively common communication method used in the industrial and automotive fields. It analyses the main cause of communication interference in the electromagnetic interference phenomenon of CAN communication in industry. Due to factors such as circuit imbalance and space electromagnetic field, the CAN bus will cause common mode interference due to radiation. The strong interference generated in the field may cause the relay to malfunction and cause the wrong signal. Therefore, this paper proposes protection measures against the malfunction of the relay from the perspective of signal input and relay triggering, and has strong anti-interference ability after testing in actual projects.

Most of the existing research in short-term power system maintenance scheduling assumes that repair is minimal when equipment fails. However, this may not always be the truth because sometimes repair after failure is imperfect. This paper investigates the impact of imperfect repair on power system maintenance scheduling. Unlike previous research which didn't consider imperfect repair, a condition-based maintenance optimization model is proposed. The model focuses on equipment deterioration failure. Firstly, a new equipment state-space diagram under imperfect repair is given. And then, the availability of power equipment considering maintenance schedule and imperfect repair is derived using the Markov process theory. Based on that, in order to determine the optimal equipment maintenance schedules, the expression of system outage cost is given. Finally, system outage cost is minimized to optimize equipment maintenance schedules. A case study is used to illustrate the effectiveness and significance of the proposed model.

The stray current generated by urban rail transit has become one of the major factors in the DC bias phenomenon of the main transformer of urban power grid. The electromagnetic field finite element method is used to theoretically calculate and analysed the geoelectric field of metro stray current. According to the mathematical model, the ANSYS finite element software is used to simulated and analysed the current under different stray currents. The results show that with the value of traction current increases, the stray current flowing into the ground increases, and the strength of the formed electric field increases.

The characteristic of the Magnetic Resonance Wireless Power Transfer (MR-WPT) system is related on the coupling coefficients between coils, so it is very important to accurately measure mutual inductance. The method of measuring mutual inductance using the primary current and the secondary voltage, when the secondary circuit is opened, is commonly used and most reliable. However, a standard sine wave generator and a linear power amplifier are needed for measuring the mutual inductance. Due to the high frequency inverter of WPT system may be has distortion, it is not recommended to be as the sine wave generator for measuring the mutual inductance. The proposed method demonstrate that, although the output current waveform of the high frequency inverter and the voltage waveform on the secondary coil are highly distorted in PWM (Pulse Width Modulation) control mode, the base component's amplitudes of these waveforms are investigated by FFT (Fast Fourier Transform), and then, the mutual inductance is calculated by using these values. According to the above contents, the experimental platform is built, and then the experiments on the different duty cycle ratio and the different frequencies, that is, including the different quantities of its high-frequency harmonics, has been done. In addition, the same operation as above is repeated on the different distances, and the results are compared with the theoretical calculation values. Consequently, the results show that the method is very close to the theoretical value, and it is very stable in whole distance range.

Responding to the continuous development of power reform and power market, referred to research of the power market operation, this paper designs operational analysis tag library, which is carried out in four dimensions: market supply and demand analysis, market structure analysis, market behaviour analysis and market operation analysis, to display and track the trend of power market operations more intuitively, and describes the operation status of the power market more comprehensively. Besides, Power Market Operation Analysis Tag Library is designed to deal with power trading management from a macro perspective with decision support.

800kV DC arrester is widely used in UHV converter stations. If long-term damp or breakdown short-circuit of the resistor is degraded during operation, the potential distribution of the arrester is unreasonable and the leakage current increases, resulting in arrester heating or even explosion, so it's necessary to analyze and calculate the potential distribution and leakage current under different degrees of degradation. In this article, the ANSYS simulation model of 800kV DC arrester was built, which was used to calculate the potential distribution and leakage current of the arrester when long-term damp and breakdown short-circuit, and the correctness of simulation results are verified by field test of leakage current.

UHV AC arresters will be degraded to varying degrees due to the operating environment, including long-term moisture, breakdown and short circuit of the resistor, which makes the increasing unevenness of potential distribution, leading to a larger area of damage and even a safety accident such as arrester explosion. Hence it's need to analyze the potential distribution of arrester under different conditions. This article carried out a series of tests of the potential distribution of UHV AC arresters when partial damp and partial short-circuit using optical fiber current method, and established the corresponding ANSYS 3D simulation model according to the actual structure and the test method, which is used to calculate the potential distribution under the corresponding test conditions. The consistency of the test and simulation results verified the correctness of the simulation model.

In view of the problems such as excessive tensile load factor of nodal bus and overload of load flow section that often occur during the trial operation of Guangdong Electric Power Spot Market, the coordination mechanism between the system and bus load forecasting results is studied in this paper. Firstly, the time-sharing credibility coordination model of the system-bus is established based on the least square method, so as to achieve the goal of load balance between upper and lower grades and the minimum overall error. Secondly, the different classification of the time-sharing credibility model is studied to adapt to different kinds of situation. Finally, a province is taken as an example to verify the effectiveness of the proposed method, and the results show that it has certain engineering application value.

An important part of China's power system reform is the implementation of releasing plans on generation and consumption of electricity. This paper discusses the policy of orderly releasing plans on generation and consumption of electricity. By sorting out its relevant policies, interpret those policies from three perspectives. Study the releasing situation of generation and consumption of electricity in northeast China, integrate the implementation plan of the three provinces and one district and lay the foundation for studying the impact of policy and policy suggestions for orderly releasing plans on generation and consumption of electricity.

In China's current power generation plan, wind power belongs to the scope of guaranteed priority generation. But with the development of wind power industry and the promotion of electricity market construction, wind power participation in market transactions has become a trend. This paper first analyses the current situation of wind power industry under the background of electric power system reform, then introduces the situation and experience of Texas electricity market with good wind power development. According to the current situation of wind power development in Northeast China, the suggestions for wind power development are put forward and the development path of wind power in the electricity market environment is formulated.

The northwest area is full of renewable energy in China, and the development of renewable energy is rapid which brings great influence on the operation of power system. With the large-scale of renewable energy, it is difficult for energy consumption in the northwest provinces, and there still exists energy curtailment in all provinces. Renewable energy consumption in the northwest area is limited by insufficient demand, potential of sending out electricity, and peaking capacity. As the basis of system operation, the research of scheduling methods provides basic data and reference for all aspects of system operation scheduling. In order to further promote the consumption of renewable energy, we study the impact of different scheduling methods on the ability of renewable energy consumption. Combining with the actual data, we analyze and evaluate the scheduling methods, comparing the characteristics of each scheduling method, and studying its impact on renewable energy consumption. Combined with relevant calculations and analysis, the optimization suggestions for exploiting the potential of renewable energy and improving consumption space are provided.

Based on the development law of electric energy, this paper puts forward the inevitability of the extensive interconnection of power system and their technical requirements. Firstly, this paper analyzes the law of energy development from the perspective of energy supply development, energy consumption development and energy transaction development. Secondly, based on China's clean energy development pattern, the concept and significance of a new generation of power systems are widely interconnected. Finally, this paper proposes the technical requirements for the extensive interconnection of the power systems, respectively constructs the key technical systems of physical interconnection and information interconnection, and analyzes the development trends of related technologies.

Generator leading phase operation can not only absorb excess reactive power under small load operation mode, but also smoothly regulate grid voltage to cope with abrupt changes in grid operation. Based on the summer small load typical operation mode of Gansu Power Grid, four calculation conditions are selected to calculate power flow, and the influence of generator leading phase operation on grid voltage and loss is simulated and analyzed. The simulation results show that no matter how the active power output distribution of generators changes in the power grid, the voltage level of the power grid under small load can be significantly improved by generator leading phase operation. However, the grid loss will increase when the generator is in leading phase operation.

Market participants and system operators are faced with price risks caused by various factors, such as congestions or market power abuse. Therefore, the price risk management in deregulated market environment is of great importance. In this paper, various risk-hedge financial instruments in PJM and Nord Pool, such as FTRs, futures, forwards and CFDs are investigated. These risk management mechanisms can be further utilized for congestion revenue allocation, speculation or arbitrage under different market circumstances.