Application Of Model Predictive Control In Voltage Control Of Wind Farm With Doubly-Fed Induction Generator

With the large-scale integration of wind power,wind farms face many challenges in operation and control.Wind power control is a key issue to solve the operation of wind farms.This paper combines the advantages of Model Predictive Control(MPC)in dealing with complex system models,uncertainties and control constraints,and analyzes and discusses the operation of Doubly-fed Induction Generator(DFIG).Based on the principle of DFIG operation and MPC theory,the MPC is applied to the DFIG rotor side excitation control to improve the DFIG and wind farm operation levels.Following shows the main work and achievements of this paper:Based on the working principle of DFIG the electromechanical transient model of the unit under wind speed fluctuation is analyzed,and the corresponding state space model is established.Based on the state space model,the Elman neural network prediction model of DFIG is further established and the prediction model is analyzed..Based on the DFIG electromechanical transient prediction model,combined with state space based model predictive control,the system control sequence is solved given the state variables,output variables and disturbance variables.Combined with the control sequence solving process,the rolling optimization and feedback are analyzed.The constraint characteristics of the parameter adjustment control in MPC are analyzed according to the specific example,and the MPC and LQR controllers are compared and analyzed.According to the influence of multiple factors such as the uncertainty of the DFIG in the control process,the complexity of the model and the constraints,the DFIG rotor excitation model predictive control is discussed to track the maximum power point based on the DFIG electromagnetic power control and the electromechanical transient state space model of MPC and DFIG.The paper also discusses the soft and hard constraints in MPC;combined with the actual wind farm operation situation in China,the paper designs the simulation model in MATLAB/simulink environment,and the proposes the control strategy The simulation results show that the proposed control strategy can reduce the influence of model uncertainty and parameter uncertainty in the control process,and achieve unit control goal under the constraints and complex models.Finally,based on the topology characteristics of the wind farm collector system and the DFIG reactive power adjustment capability,a DFIG control strategy considering the characteristics of the wind farm collector system and reactive power regulation is proposed to track the wind power and reduce the voltage difference between adjacent units.The power output of the unit is controlled and follows the goal;combined with the actual wind farm operation situation in a certain place,the simulation model in MATLAB/simulink environment is designed,and the proposed control strategy is verified.The control strategy proposed in this paper can guarantee the maximum wind energy tracking.At the same time,the terminal voltage difference between the units on the same set of wires is reduced,and the voltage level inside the wind farm is improved.