Research On Mechanism Of Cluster Charging Station Participating In Supplementary Frequency Regulation

With the large-scale grid connection of renewable energy such as wind power and photovoltaic,as well as the access of new loads such as smart homes and energy storage facilities,the frequency adjustment problem of power systems is becoming more and more complicated.Traditional generator sets such as hydropower units and thermal power units are also difficult to track the change in load accurately.As a new type of load,electric vehicles have battery properties and are a mobile energy storage setting.The gradual popularization of electric vehicles provides a new solution to solve the frequency control problem of the power grid.Firstly,the V2G system and its core components,the two-way charger and battery management system,are introduced.The three control modes of electric vehicles,namely centralized,decentralized and re-powered,are discussed and analyzed.On this basis,the electric vehicle control framework with "cluster charging station" as the core is established.With the principle of "distributed access and centralized control",the distributed access of electric vehicles through the cluster charging station is managed and controlled.Then introduces the causes of power system frequency fluctuations,generator-load model,prime mover governor model and electric vehicle frequency modulation model.According to the fast response characteristics of electric vehicles,based on the butterworth low-pass filter,an AGC model suitable for electric vehicles was established.The electric vehicle is divided into two groups by counting the vehicle charge level,and the controllable capacity of the single electric vehicle is calculated on the basis of this.Considering the user's will and battery capacity,a power allocation method based on battery state of charge is proposed with power constraints and energy constraints,to reduce the influence of frequency modulation on battery SOC.Finally,according to the above method,a single-area power system model is established on the Matlab/Simulink simulation platform,and the dynamic simulation analysis of the cluster charging station participating in the supplementary frequency regulation carried out.The simulation results show that the AGC model which can decompose the regulation signal fully utilizes the fast response characteristics of the electric vehicle and can respond quickly to the system frequency fluctuation.And participation in supplementary frequency modulation has little effect on the SOC of electric vehicles,which will not affect users' travel.The simulation results verify the feasibility and effectiveness of the proposed method.