Time Varying PO-PID Load Frequency Control Method Considering Wind Power Randomness

With the increasingly serious contradiction between environmental protection and energy demand,clean energy represented by wind power has developed rapidly.When wind power participates in automatic generation control(AGC)for power grid frequency regulation,due to its unique intermittence,randomness,environmental impact and other reasons,it will cause changes in relevant parameters of the power system,which will bring adverse effects on the safe and stable operation of the system.Based on this,this paper analyzes the influence mechanism of wind speed uncertainty on system parameters,and proposes a time-varying predictive optimization and proportional integral derivative(PID)cascade control method to deal with the negative impact of wind power random fluctuations on AGC better.Firstly,the control principle and objective of AGC system are introduced,and the system composition and mathematical model of each unit are analyzed.Based on the description of wind turbine model,the control strategies of wind power participating in power system frequency regulation are compared and selected,and the AGC model of power system with wind power is constructed accordingly.Secondly,the influence of wind speed time-varying characteristics on wind turbine inertia time constant is quantitatively analyzed,and the correlation between random wind speed and power system inertia time constant is further described.The strong and weak characteristics of correlation under different parameters are verified by Matlab /Simulink simulation,and the key variable parameters are selected.On this basis,considering the adverse effect of model parameter changes on system stability caused by random wind power,a time-varying predictive optimal PID(PO-PID)control method is proposed.Combined with the quantitative expression between inertia time constant and wind speed of power system,the AGC time-varying system model with wind power is constructed,and the time-varying model predictive control(MPC)algorithm is used to optimize the control.Considering that the optimization process is to optimize the prediction sequence and lack of pertinence to the current value,the time-varying model predictive controller is connected in series with PID,and the former prediction optimization result is adjusted through the latter PID to obtain better control effect.Finally,a two area AGC system model with wind power is built in matlab/simulink.By comparing the control results of time-varying PO-PID,time-varying MPC,traditional MPC and Parameter Optimization PID under different wind speed conditions and load disturbance conditions,the effectiveness of the proposed method is verified.The simulation results show that when wind power participates in the load frequency control of power system,the proposed method can dynamically adjust the control variables according to the change of AGC system parameters caused by the change of wind speed,and has better frequency control effect.