Research On The Frequency Regulation Control Strategy For The Electric Vehicles Considering The Lifespan Of Power Batteries

With the development of the electric vehicles and the power batteries, the Vehicle-to-Grid technology are growing fast. The response time of power batteries is short. They can transitions from charging state to discharging state rapidly without ramping-rate constraints. Thus, electric vehicles show the significant adv antages in the field of peak load regulation and frequency regulation. Along with the increases in load growth and the ratio of new energy resources, there’s more pressure on frequency regulation of power system. When the stagnant electric vehicles participate in the frequency regulation, the power system can became more stable and economic. Merely, the process of frequency regulation can accelerate the capacity loss of power batteries. On account of this situation, the grid company is supposed to compensate electricity vehicles users reasonably, which will improve the users motivation and guarantee the quantity of vehicles.Firstly, the cycle life prediction model of iron phosphate-lithium power battery is built based on cycle index of batteries, ancient temperature, depth of charge and discharge and charge and discharge rate. Considering the droop characteristics of generator and the parameters of batteries, the simulation model of power batteries used in frequency regulation is built.Secondly, the single-region power grid model with electric vehicles is built to analysis the stability of power system when electric vehicles participate in the primary frequency regulation. In addition, according to the capacity loss of power batteries, different control strategies of charging and discharging state are compared. On the basis of the better strategy, the capacity loss of electric vehicles which join the primary frequency regulation in different areas estimated. And the result can help the grid company compensate electric vehicles users reasonably.Thirdly, the simulation model with electric vehicles joining the secondary frequency regulation is developed. In this model, the characteristics of travel behavior are considered. According to the probability distributi on of electric vehicles SOC, different allocation strategies of frequency regulation signals are generated. In the light of the batteries energy excursion and frequency quality, different control strategies are compared and analyzed. Besides, two special w orking conditions are analyzed to verify the influence of frequency regulation with electric vehicles.Finally, the cost and profit of users are estimated when electric vehicles participate in frequency regulation with different strategies. Based on the s imulation result, the grid company is supposed to compensate electric vehicles users reasonably, which will improve the users motivation and guarantee the stability of power system.