基于动态阻抗补偿的双馈式风力发电机低电压穿越新策略

低电压穿越(LVRT)能力是限制双馈式风力发电机(DFIG)大规模并网运行的瓶颈问题。电网电压跌落时保持定子端电压稳定是解决LVRT的根本所在。提出一种动态阻抗补偿机端电压的新策略,当检测到电网电压下降时,流经快速调节后动态阻抗的电流迫使DFIG机端电压升高,确保定子端电压处于可控范围之内。通过单相等值电路分析了LVRT过程中电机内部各量的变化,证明了机端电压补偿策略的可行性,并给出动态电阻的实现电路。最后通过仿真验证了该补偿策略下电机内部响应均符合低电压穿越要求。

A New Strategy of the low voltage ride through for Doubly-fed wind generator based on dynamic impedance compensation

Low voltage ride through capability is a important issue to limit the DFIG connected to the grid in a large scale. It is essential to solve the LVRT when grid voltage sags to keep stator terminal voltage stability. This study proposes a new strategy to improve the LVRT capability in DFIG. The proposes scheme is a dynamic impedance compensation. When grid sags detected, the current through the dynamic impedance after the rapid regulation forced DFIG terminal voltage rise, and to ensure that the stator terminal voltage is in the controllable range. Analysis the volume changes of motor internal in the LVRT process by a single phase equivalent circuit, proved terminal voltage compensation strategies. And the dynamic resistance circuit is given. Finally through the simulation it is verified that the compensation strategy of motor response are consistent with the LVRT requirements.