Study On Smoothing Control Of Large-inertia Wind Power Generation System

Wind power generation,as one of the most important new energy generation forms in the future,has enormous social,economic and environmental benefits to solve the problem of resource scarcity and environmental pollution.However,due to the high randomness and intermittence of wind energy,the output fluctuation of wind turbines is relatively large,especially in the transitional operation zone near the rated wind speed.Due to the frequent switching of control strategies,the output and mechanical load of generators are prone to frequent jumps,which has adverse effects on the safe and stable operation of power grid and the health of unit equipment.Therefore,it is of great theoretical significance and engineering application value to study the power smoothing strategy of wind power generation system in the whole wind condition(especially in the rated wind speed transition zone)to ensure that wind turbines are both grid-friendly and equipment-friendly.Firstly,the working principle of wind power generation system is introduced,the mathematical model of wind power generation system is established through mechanism analysis,and the large-inertia characteristics of large-scale wind power generation system are analyzed concretely.The single-machine control characteristics of the large-inertia fan are described theoretically.Secondly,aiming at the respective control objectives of the main operation interval,a full-condition integrated control system with the main operation interval controller is designed,which includes the maximum power tracking controller based on the optimal torque control(OTC)strategy and the constant power controller based on the pitch angle-electromagnetic torque coordinated control with gain correction.Based on the joint simulation of FAST and MATLAB/Simulink,the correctness and effectiveness of the model and control strategy are verified.Thirdly,in order to suppress the fluctuation of generator output and mechanical load in the transition operation zone near the rated wind speed,a disturbance-free switching control strategy for wind power generation system based on gain adaptive is proposed to achieve smooth control of the transition operation zone near the rated wind speed.By analyzing the switching characteristics of traditional control strategies near rated wind speed,the theoretical basis of controller gain regulation is proposed.Furthermore,a gain adaptive smoothing switching control strategy based on Fourier transform is designed to make the electromagnetic torque and output power transition smoothly in the switching process of the controller between the two operating intervals below and above rated wind speed.Finally,the comparative simulation results based on FAST platform show that the proposed gain adaptive smooth switching control strategy based on Fourier transform can effectively suppress the fluctuation of generator output,and the mechanical load of the unit during the transition process is lower.This strategy has the advantages of grid friendliness and equipment friendliness,and has high engineering application value.Finally,the comparison simulation experiment based on the FAST platform shows that the switching control strategy can effectively restrain the fluctuation of generator output,lower the mechanical load,and have the advantages of power network friendliness and equipment friendliness.It has certain engineering application value.