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

Active disturbance-rejection control of wind turbines based on double-fed induction generator under unbalanced grid voltage

本文提出电网电压不平衡工况下双馈感应电机(DFIG)的自抗扰控制(ADRC)方法,抑制不平衡电压引起的电磁转矩和无功功率波动,延长风力发电机组的工作寿命.在正、负序同步旋转坐标系中推导了电网电压不平衡工况下DFIG的电磁转矩表达式,计算出消除电磁转矩波动所需的负序转子电流,将其叠加到正序转子电流参考值上,以减小电磁转矩波动.采用ADRC实现对转子电流的有效控制,减少控制器对发电机精确模型的依赖,提高控制系统的鲁棒性.仿真结果表明所提出的控制方案有效地减小了电网电压不平衡工况下DFIG的电磁转矩和无功功率波动,同时减小了不平衡电流,有利于延长DFIG风力发电机组的工作寿命.

An active disturbances rejection control （ADRC） scheme of the doublefed 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 positivesequence 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.