Frequency Regulation Strategy Of Electric Vehicle Aggregator Considering Wind Power Participate In Power System

As environmental pollution and traditional energy shortages become more and more obvious,electric vehicles with the advantages of energy conservation and environmental protection have been vigorously developed.At the same time,renewable clean energy,represented by wind power,has increasingly attracted worldwide attention and is connected to the grid in the form of distributed generation.However,the randomness of large scale electric vehicles and the uncertainty of wind power generation will have an impact on the safe and stable operation of grid frequency.Therefore,this paper analyzes the strategy of frequency regulation of electric vehicle aggregators and wind turbines participating in the system to suppress the system frequency fluctuations as the end result of the frequency regulation strategy.Firstly,the dynamic controllable energy changes of electric vehicles are analyzed in the load frequency control model.The influence of electric vehicles on the frequency regulation of the system,from the perspective of energy,demonstrates the characteristics of electric vehicles with traffic attributes on the network.Then,taking into account the frequency regulation power distribution problem of electric vehicle aggregators into the grid frequency regulation,a load frequency control strategy based on real-time prediction of the controllable capacity of electric vehicles is proposed.Finally,based on the operating characteristics of the double-fed variable-speed wind turbine,the frequency modulation model of the wind turbine is established,and the control strategy for the joint frequency modulation of the electric vehicle aggregator and the wind turbine is initially proposed.Details as follows:Based on the driving rules of four types of electric vehicles in China,the controllable quantities of various types of electric vehicles are calculated combined with the state transition characteristics of electric vehicles.On the basis of the initial energy storage of electric vehi-cles,the dynamic model of real-time controllable energy of electric vehicle is established.Finally,a load frequency control model that takes into account the dynamic changes of the electric vehicle's real-time controllable energy is established,which verifies that the real-time controllable energy of the electric vehicle affects the formulation of the frequency regulation strategy of the electric vehicle participating in the system.There are two unreasonable problems when electric vehicles provide power grid with regulation service.One is that the emergence of electric vehicles separated from grid randomly may cause the unreasonable assigned regulation task for electric vehicles and the other is that charge and discharge of electric vehicles frequently in regulation process are harmful to batteries.Aiming at the problems above,this paper presents a frequency regulation control strategy for electric vehicle aggregator considering electric vehicles' demand.The research divides electric vehicles participating in frequency regulation into discharge group and charge group,and controls the number of electric vehicles' conversions between discharge group and charge group to decrease the charge and discharge times.On the basis of the above,the real-time prediction of the controllable capacity of the electric vehicle aggregator is carried out,and the regulation assignation is proposed to electric vehicles of charge and discharge groups,respectively.The frequency of charge and discharge conversion of the electric vehicle can be effectively controlled while the electric vehicle participates in system frequency regulation.According to the characteristics of wind turbines,by analyzing the stability of the sub-optimal operation state of the wind power,frequency regulation model is established by three control methods consisting of virtual inertia control,droop control,and variable pitch angle control;combining with the proposed control strategy for electric vehicle aggregators,a control strategy is proposed for electric vehicle aggregators and wind power combined with frequency regulation through the allocation of system frequency requirements.The simulation shows that wind power can share the pressure of the system's frequency regulation,and its joint frequency tuning effect with the electric vehicle aggregator is better.