Load Frequency Controller Design Considering Vehicle To Grid

In recent years,electric vehicles has attracted worldwide attention as an efficient measure to overcome the environmental pollution problem caused by traditional fuel-powered vehicles.As electric vehicles are powered by electric power,large-scale charging of electric vehicles will have an impact on the existing power system.The most obvious is on the load frequency of the grid.Research shows that the batteries of electric cars can not only absorb energy from the power grid,but also serve as a mobile energy through a certain way to provide the schedulable electricity capacity for the power system,thus can serve as an auxiliary for load frequency control.Compared with the traditional system,the structure of the power system with vehicle to grid is complex.It is not only affected by uncertainties such as model uncertainty,nonlinearity and external disturbances,but also there exist problems such as strict disturbance rejection requirements and inaccurate modeling.In order to solve these problems this paper studies load frequency control with electric vehicle network participating in power system.First,to show the impact of large amount of electric vehicles on the load frequency control of the power grid,an electric vehicle network model is established,which consists of the centralized control system of electric vehicle,the equivalent control model of V2G,the schematic of V2G,the battery structure of Thevenin model,the response frequency droop characteristic curve.The impact that large numbers of electric vehicles recharge from the power grid,is used as an external disturbance.Second,to improve the control performance of the system due to uncertainties and disturbances,the dynamic matrix control(DMC)method and the active disturbance rejection control(ADRC)method are studied.DMC uses the step response of the controlled plant as the predictive model,adopts receding-horizon optimization and feedback correction control strategy.ADRC treats the controlled plant model uncertainty as the total disturbance,estimates the disturbance through extended state observer,and compensates it using feedback.Simulation results show that the two control strategies improve the speed and stability of the power system considering the electric vehicle network,and ADRC method is better in control performance.Finally,since DMC and ADRC usually result in high-order controllers,to solve the implementation issue of the above two control strategies,the two controllers designed from DMC and ADRC are approximated by the traditional PID controller in the frequency domain.It is shown that the approximated PID controllers can achieve similar performance as the DMC and ADRC controllers.Simulation results show that the system with the electric vehicle network is more rapid and stable than that without vehicle participation.