基于转子串联电阻的双馈风力发电机低电压穿越

Low voltage ride-through of doubly-fed induction generator based on rotor series resistor

讨论双馈风力发电机组低电压穿越中,转子串联电阻控制方式时转子侧变流器有功、无功功率的分配原则,给出有功、无功电流的极限表达式,提出一种转子串联电阻低电压穿越功率协调控制策略。在电网电压跌落转子电流超过其阈值时,该方案一方面控制转子变流器有功电流输出,使其满足转子串联电阻投入后所消耗的有功功率;另一方面考虑双馈电机暂态稳定性,使双馈电机工作在无功支持模式,优先向电网输出一定的感性无功功率。实验结果表明,该控制方案具有比撬棒保护更好的暂态性能,同时有助于电网电压的快速恢复,有利于其他并网负载的安全运行。

The principle of active and reactive power assignment in the rotor series resistor control mode for the rotor-side converter of DFIG（Doubly-Fed Induction Generator） during the LVRT（Low Voltage Ride- Through ） is discussed,the expressions of their active and reactive current limits are given and a corresponding scheme of coordinated LVRT power control is put forward. When the rotor current exceeds its threshold due to the grid voltage sag,on the one hand,the output active current of grid-side converter is controlled to match the active power consumption of the operating rotor series resistor;on the other hand, the DFIG,for its transient stability,is set in the reactive power supporting mode to preferentially output a certain inductive reactive power to grid. The experimental results show that,compared with the Crowbar protection,the proposed control scheme has better transient performance,beneficial to the fast recovery of grid voltage and the safe operation of other grid-connected loads.