The Control Method Of Electric Vehicles Participating In Frequency Regulation Of Power Systems

Distributed energy storage plays an important role in electric system because of the developing economy, increasing demands of electric power and the serious environmental pollution. Besides, electric vehicle (EV) is paid more attention due to the development of renewable energy technology and higher awareness of the concept of low carbon, energy conservation and emission reduction. Electric vehicle is a new type of special load for the grid and it is also regarded as one of the most promising distributed energy storage unit. With the increase in proportion of the EVs in grid and the continuous improvement of the V2G technology, EVs provide the grid with spinning reserve and ancillary services such as frequency regulation by changing its charging/discharging power. Many researches show that frequency regulation for power systems provided by EVs is one of the most promising V2G ancillary services. Thus, the methods of EVs participating in frequency regulation based on the technology of V2G are studied in this paper. Research work can be summarized as follows.Firstly, the frequency regulation system containing V2G is modeled, Further, the advantages and disadvantages of the current control methods (decentralized and centralized V2G control methods) for the frequency regulation by EVs are concluded by comparison and analysis, according to different forms of electric vehicle participation in grid. The analytical conclusion is the basement for our researches.Secondly, a distributed V2G control method is presented for EVs responding to the frequency dynamically. The frequency deviation of power systems and the variation trend of the frequency deviation are all considered in the proposed dynamic method in this study, which is quite different from static control strategy. The dynamic method can adjust the monitoring cycle and the response threshold value according to the frequency deviation and variation trend when an abnormal frequency occurs in power systems.Finally, a V2G centralized control method for large-scale centralized charging EVs is proposed. EVs are divided into random model and fixed model according to the value of SOC, and different response strategies are made by considering the demands of EVs under different states of SOC. At the same time, an optimal control method of frequency regulation is proposed by considering the inter-coordination between centralized control center and electric vehicle.The decentralized and centralized V2G control method is researched in this paper, respectively for EVs participating in the frequency regulation service of power systems. The researches in this paper are prospective and will have practical significance and reference value with the development of the future EVs and related technologies.