Active disturbance-rejection control of wind turbines based on double-fed induction generator under unbalanced grid voltage
电网电压不平衡工况下双馈感应风力发电机组的自抗扰控制

An active disturbances rejection control (ADRC) scheme of the double-fed induction generators (DFIG) under unbalanced gird voltage is proposed to suppress electromagnetic torque pulsations and reactive power pulsations caused by unbalanced gird voltages, with the purpose of extending the working life of wind turbines. The expressions of the electromagnetic torque of DFIG under unbalanced gird voltage are derived in the positive-sequence and negative-sequence synchronously rotating frames, and the negative-sequence rotor current for eliminating electromagnetic torque pulsations are calculated, which is added to the positive sequence rotor current reference value to minimize torque pulsations. ADRC is introduced to achieve effective control of rotor current, which reduces the dependency of the controller on the exact model of generator and improves the robustness of the control system. The simulation results show that the proposed control scheme effectively reduces electromagnetic torque pulsations, reactive power pulsations and unbalanced current of DFIG under unbalanced grid voltage, extending the working life of the wind turbines based on DFIG.