Transactive Control and Coordination of Distributed Assets for Ancillary Services

Subbarao, Krishnappa ; Fuller, Jason C. ; Kalsi, Karanjit ; Somani, Abhishek ; Pratt, Robert G. ; Widergren, Steven E. ; Chassin, David P.

关键词: smart grid;    demand response;    ancillary services;    transactive energy;    Environmental Molecular Sciences Laboratory;   

DOI  :  10.2172/1113609
RP-ID  :  PNNL-22942
PID  :  OSTI ID: 1113609
Others  :  Other: 21091
Others  :  TE1201000

美国|英语

来源: SciTech Connect

【 摘 要 】

The need to diversify energy supplies, the need to mitigate energy-related environmental impact, and the entry of electric vehicles in large numbers present challenges and opportunities to power system professionals. Wind and solar power provide many benefits, and to reap the benefits the resulting increased variability???forecasted as well as unforecasted???should be addressed. Demand resources are receiving increasing attention as one means of providing the grid balancing services. Control and coordination of a large number (~millions) of distributed smart grid assets requires innovative approaches. One such is transactive control and coordination (TC2)???a distributed, agent-based incentive and control system. The TC2 paradigm is to create a market system with the following characteristics: ??? Participation should be entirely voluntary. ??? The participant decides at what price s/he is willing to participate. ??? The bids and responses are automated. Such an approach has been developed and demonstrated by Pacific Northwest National Laboratory for energy markets. It is the purpose of this project to develop a similar approach for ancillary services. In this report, the following ancillary services are considered: ??? spinning reserve ??? ramping ??? regulation. These services are to be provided by the following devices: ??? refrigerators ??? water heaters ??? clothes dryers ??? variable speed drives. The important results are summarized below: The regulation signal can be divided into an energy-neutral high frequency component and a low frequency component. The high frequency component is particularly well suited for demand resources. The low frequency component, which carries energy non-neutrality, can be handled by a combination of generators and demand resources. An explicit method for such a separation is obtained from an exponentially weighted moving average filter. Causal filters (i.e., filters that process only present and past values of a signal) introduce delays that can be issues in some signal processing applications that treat the high frequency part as a noise to be eliminated. For regulation, the high frequency component is an essential part of the signal. The delay in the low frequency component is not a problem. A stochastic self-dispatch algorithm determines the response of the devices to the regulation signal. ??? In an ensemble of devices under normal operation, some devices turn on and some turn off in any time interval. Demand response necessitates turning off devices that would normally be on, or turning on devices that would normally be off. Over time, some of these would have turned off on their own. A formalism to determine expectation values under a combination of natural and forced attrition has been developed. This formalism provides a mechanism for accomplishing a desired power profile within a bid period. In particular, a method to minimize regulation requirement can be developed. The formulation provides valuable insights into control. ??? Some ancillary services???ramping to absorb unforecasted increase in renewable generation, and regulation down???require the demand resources to increase their energy use. Some resources such as HVAC systems can do this readily, whereas some others require enabling technology. Even without such technology, it is possible to arrange refrigerators and water heaters to have an energy debt and be ready to increase their energy use. A transactive bid mechanism of revolving debt can be developed for this purpose. Dramatic changes in control systems, architecture and markets are expected in the electrical grid. The technical capabilities of a large number of devices interacting with the grid are changing. While it is too early to describe complete solutions, TC2 has attractive features suitable for adapting to the changes. The analyses in this report and the activities planned for FY 14 and beyond are designed to facilitate this transition.