计及工作点偏移的减载风电系统频率响应模型OA北大核心CSTPCD

With the increasing grid-connected capacity of wind power,using deloaded wind turbines(WTs)to participate in the primary frequency regulation is of great significance in safeguarding system frequency stability.However,the working point of the WT shifts with its rotational speed change,which results in the actual capacity of the primary frequency regulation of the WT smaller than the desired value.Therefore,the interaction between the power tracking control of deloaded WTs and the integrated inertia control after a frequency fault is firstly analyzed,and the basic principle that the working point shifting of the WTs leads to the weakening of the frequency regulation effect is pointed out.Secondly,the wind power-frequency transfer function is derived based on the rotor motion equation of the WTs,and the system frequency response(SFR)model is established considering the working point shifting of the deloaded WTs.The least square method is also used to reduce the order of the proposed SFR model,and an analytical formula of the system frequency nadir is deduced.Then,in view of the shortcomings of virtual inertia control,such as power backflow during the frequency recovery and noise amplification in differential links,it is proposed to replace the integrated inertia control with droop control.Meanwhile,in order to make the deloaded WTs obtain the desired frequency regulation effect,the control parameters of the WTs are modified based on the frequency nadir and the steady state frequency indices,and calculation methods for the two equivalent droop coefficients are proposed.Finally,a four-machine two-region model is established on the MATLAB/Simulink platform to verify the effectiveness of the proposed order reduction method and the correction method.