一种改进的双馈感应发电机低电压穿越控制策略

An improved low voltage ride-through strategy for doubly fed induction generator

为提高双馈感应发电机的低电压穿越能力,对转子侧换流器考虑了电网故障时定子磁链变化对有功、无功解耦的影响,并将反映电流耦合及定子磁链变化的附加量作为前馈分量加入电流指令值,对传统矢量控制策略进行了改进。对网侧换流器,提出一种考虑直流环节两侧功率不平衡及电网电压突变的改进控制策略。仿真验证了改进方案对转子过电压、过电流及直流母线电压波动均有很好的抑制作用,有效提高了双馈机的低电压穿越能力。

In order to enhance ability of low voltage ride-through （LVRT） of doubly-fed induction generator （DFIG）, the traditional vector control strategy of DFIG is improved in this paper. When grid failure occurs, for rotor side converter, changes of stator flux will affect decoupling control of active power and reactive power. Therefore, a feedforward component, which is concerned with the coupled current and the changes of stator flux, is added to commanded current value. For grid side converter, power imbalance between two sides of DC bus and changes of grid voltage are both taken into account in the improved control strategy. Simulation results show that the improved strategy has a good performance on suppressing rotor over voltage, rotor over current and DC bus voltage fluctuation, therefore, it can effectively improve ability of low voltage ride-through of doubly-fed induction generator.