Research On Electric Vehicle's Participation In Power Grid Voltage Regulation Based On Model Predictive Control

With the increasing pressure of environmental degradation and energy shortages,electric vehicles(EVs)with renewable clean energy are becoming more and more widely used.However,the large-scale access of EVs to grid will inevitably have a great negative impact on the grid.Such as overload,frequency fluctuations,voltage fluctuations,etc.Therefore,the EVs which have excellent energy storage characteristics,flexibility and fast response can provide better provide auxiliary services such as voltage regulation for the power grid.At present,how to use EVs to provide voltage regulation services for the power grid has been widely concerned by scholars.But the conventional methods still have great challenges in how to balance the charging requirements of EV users,the economics of users participating in voltage regulation,and the stability of grid voltage.Applying advanced control techniques in V2 G systems can achieve better performance.Model predictive control(MPC)is one of the few advanced control techniques capable of dealing with both linear and nonlinear models.However,most of the current MPC-based research on EVs only consider one-sided factors,such as battery or energy management.In view of the above problems,this paper makes a depth study on the control method of EVs participating in grid voltage regulation based on MPC.The main research contents are as follows:Firstly,based on the basic working principle of EVs participating in grid voltage regulation and the general grid system structure,this paper proposes a system topology of EVs participating in grid voltage regulation.Based on the system network model and the EV charging model,the total linear state space model of the controlled object is established.Secondly,based on the above system model,this paper designs a MPC-based control strategy for EVs participating in grid voltage regulation.It includes:(1)constraints: charging capacity constraints,charger limitations,reactive power compensation device limitations and voltage constraints;(2)objective function: minimize the deviation of grid voltage and SOC from their desired value;(3)a two-stage hierarchical control scheme based on MPC which includes the optimal reachable reference calculation of given trajectory and the design of predictive controller.Thirdly,on the basis of the above-mentioned research,combined with the charging cost of EV users,battery degration cost and the economic benefits of users providing corresponding services,a control method based on MPC which considers the economic benefits of users is further designed.Based on the above research work,the simulation and verification of the proposed two multi-objective optimization control models are carried out on the MATLAB platform.The simulation results show that the proposed control method can achieve better performance and ensure the stability of the grid voltage than the traditional reactive power compensation device on the basis of satisfying the user's charging demand.At the same time,EVs are encouraged to participate in the voltage regulation service,which can effectively reduce the cost and expenditure of users,and is conducive to the promotion of EVs.