Technology Of Wind Farm STATCOM Based On Model Predictive Control

With the popularization of wind power generation,the influence of reactive power in wind power generation on the power quality of power systems has become increasingly prominent,and it has become one of the major constraints on the development of wind power on a large scale.This paper will focus on the ones most affected by changes in wind speed.As a research object,the cage-type power generation system corresponds to the reactive power compensation device STATCOM used in a wind farm for reactive power compensation strategy research.The research shows that due to the influence of wind speed changes,the reactive power generated by the wind power system is constantly changing,which causes problems such as the power factor at the grid point and voltage fluctuations at the grid side.Therefore,it is important to ensure that the STATCOM device quickly and accurately compensates for reactive power.Firstly,based on the mathematical model,this paper analyzes the characteristics of wind speed and the structure of the wind farm.The principle of generating reactive power for wind turbines and transformers is presented using vector diagrams.Through the simulation analysis,under the influence of wind speed changes,wind power systems The change of reactive power and the fluctuation of the voltage at the grid connection point provide a theoretical reference basis for the subsequent improvement of the compensation effect of the reactive power compensation equipment in the wind farm.In order to quickly and accurately compensate the reactive power control objective of the system,the traditional PI control is replaced by predictive control.Based on the working principle and topological structure of STATCOM,the STATCOM is transformed by the Clark model in the three-phase stationary coordinate system.Based on the switch model in the two-phase stationary coordinate system,based on this,the predictive controller of the current loop of the system is designed,and the selection range of the parameters under the stability of the controller is given.Under the premise of ensuring the stability of the controller,the control effect is the most Optimally,the controller parameters are selected and the response speeds of the PI controller and the predictive controller are compared through simulations to verify the superiority of the predictive control in response speed.Considering the inherent delay in practical applications,a delay compensation method is proposed,which effectively increases the system bandwidth.The system parameters may change in the actual environment.The method of parameter identification is introduced,and different forgetting is discussed.The identification effect of the factor value gives the best identification parameter.Aiming at the influence of grid-side voltage fluctuation on system identification,a parallel observer is proposed to estimate the voltage disturbance and system parameter changes in real time,and the results are fed forward to the controller,which improves the system's prediction accuracy and increases the system's accuracy.In terms of robustness,the stability condition of the observer is finally given by the Lyapunov function.A system model is built in the simulation to verify the effect of the reactive power compensation in the wind farm,and the PI controller is compared to improve the stability of the power system.The physical hardware platform of STATCOM based on d SPACE was built.The main circuit system based on STATCOM,the auxiliary circuit system for signal processing and transformation,the control system based on d SPACE,and the reactive power system for reactive power characteristics of simulated wind farm were designed.It is shown that the designed STATCOM device has static and reactive power compensation capability.It responds to reactive power demand in half the power frequency cycle.Under the condition of constantly changing reactive power,the voltage drop at the grid connection point is less than 3%,which satisfies national wind power requirements.Voltage fluctuation requirements at the grid connection point.