Optimal Configuration Of Energy Storage Capacity Under The Access Of Electric Vehicles In V2G Mode

In the microgrid,the energy storage(ES)device and the photovoltaic(PV)system cooperate to supply power to the load,which can store the excess PV power generation,effectively reduce the peak load of the grid and alleviate the pressure of power supply during the peak period.With the popularization and application of electric vehicles(EVs),the role of EVs can also be reflected,EVs in microgrid can be used as both load and energy storage equipment.When large-scale EVs are connected to the power grid,they can be charged as electricity load when the grid load is low.When the grid load is high,they can transport electric energy to the grid as a distributed power source,which plays a role of "Peak cut " for the grid load.This paper mainly studies the optimal allocation of PV ES capacity under the orderly charging and discharging mode of EVs.The specific work is as follows:(1)This paper established a mathematical model for the optimal configuration of PV ES capacity,performed a unified optimization calculation on the battery capacity,power,battery charge and discharge power of PV ES system in the park,and obtained the optimal battery charge and discharge strategy and battery configuration.In the current optimal allocation of energy storage capacity,the premise is that the available capacity of the battery remains unchanged throughout the life cycle.But in the actual system operation,a certain degree of capacity loss will occur with the recycling of ES batteries.Moreover,traditional ES configuration method sets the number of cycles of the battery to the rated value,which leads to the economy of the system is not the optimal result.We set the number of battery cycles as optimization variables to explore the relationship between the number of battery cycles,battery capacity and system economy under capacity attenuation.(2)In the case of disordered charging and discharging of EVs,the load will appear to be "peak-to-peak",which brings challenges to the operation of the power grid.In order to reduce the impact of the addition of EVs on the power grid,this paper established an orderly EVs charging and discharging model guides the charging and discharging behavior of EVs.We take the peak and valley duration and starting time of the time-of-use price of EVs as optimization variables,and the charging and discharging cost of EVs users and suppressing load fluctuations as the objective function,using Monte Carlo method iterates the charging and discharging power of EVs,and obtains the optimal starting time and duration of peak-valley price of electric vechicles under the optimization of genetic algorithm.(3)Finally,this paper established a multi-objective optimization model of PV system capacity allocation under the V2 G access of EVs to balance the interests of power grid,ES system and EVs users.The capacity and power of the ES battery,as well as the charging and discharging power of the battery,the power of purchasing and selling electricity,and the starting time and duration of the peak and valley electricity price of the EVs are taken as the optimization variables,and the orderly charging and discharging model of the EVs is established to guide the charging and discharging behavior of the EVs,so that the interests of the power grid,the energy storage system and the EVs users can be maximized.Simulation results show that this method can not only reduce the difference between peak and valley,but also bring benefits for ES system and EVs users.