Droop control Based Seamless Transfer Strategy for Three-phase Converter in Microgrid

2018 2nd International Conference on Power and Energy Engineering

Zhao, Guopeng^1,2 ; Zhou, Xinwei^2 ; Yang, Hongwei^2 ; Xu, Feng^3 ; Wang, Yanjie^2

State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources, North China Electric Power University, Beijing

102206, China^1

School of Electrical and Electronic Engineering, North China Electric Power University, Beijing

102206, China^2

State Grid Zhejiang Electric Power Research Institute, Zhejiang

310000, China^3

关键词: Control strategies;    Droop control strategies;    Grid-connected modes;    Islanding conditions;    Islanding detection;    Power supply quality;    Seamless transfer;    Three-phase converter;   

Others  :  https://iopscience.iop.org/article/10.1088/1755-1315/192/1/012028/pdf
DOI  :  10.1088/1755-1315/192/1/012028

来源: IOP

【 摘 要 】

This paper proposes a seamless transfer strategy based on the droop control strategy for three-phase converter in microgrid, which consists of the voltage limiter and the frequency limiter. In grid-connected mode, both the two limiters don't work, and the VSC is controlled by PQ control, transmitting constant power between micro-sources and power grid. When the unplanned islanding occurs, the PCC voltage and frequency may exceed the allowable range because the reference of active power and reactive power are not equal to the loads power. Then the voltage limiter and the frequency limiter begin to take effect, ensuring the power supply quality for loads. The difference between the input signal of these two limiter and the output signal will pass through the proportional regulator, and the new references of active power and reactive power can be obtained according to the droop curve. After the islanding detection detects the islanding condition, the control strategy will be changed to the droop control. All the converters can work in parallel and provide the voltage and frequency supply for loads. At last, the simulation results verified the proposed seamless transfer strategy.