永磁直驱风机低电压穿越协调控制策略

Coordinated Low Voltage Ride Through Control Strategy for Permanent Magnet Direct Drive Wind Turbine

已有的平衡控制策略无法同时兼顾直流侧电压稳定和并网有功无2倍工频波动,为此提出一种适用于永磁直驱风机的改进低电压穿越协调控制策略。该策略基于功率平衡思想,电网电压不对称故障期间,利用机侧变流器追踪并网输出有功,确保直流侧两端的功率流动基本平衡;通过在直流侧增加前馈控制环节,在消除并网有功2倍工频波动分量的同时,可维持直流侧端电压稳定;通过修正网侧变流器的参考电流指令,可使网侧电流维持在额定值附近。基于Matlab/Simulink搭建了永磁直驱风电仿真系统,验证了其有效性。在电网单相、两相短路故障时,该策略均可在抑制直流侧电压和并网有功波动的同时,有效地限制网侧电流幅值,更好地支持系统低电压穿越。

Under the existing balance control strategy,DC side voltage stability and grid connected active power which has no two times frequency fluctuation can′t take into account,an improved coordinate low voltage ride through strategy was put forward to suit for permanent magnet direct drive wind turbine.The strategy was based on the power balance theory,during the power grid voltage asymmetry fault period,the machine side converter and grid side converter output active were kept consistent in low voltage transient period,to ensure the DC side active power balance;adding the feedforward control loop in DC side,the two times frequency fluctuation of grid connected active power was eliminated,and the DC side voltage could be maintained stable at the same time;revising grid side converter current reference instructions,grid side current was prevented out of range.The permanent magnet direct drive wind power system was built on Matlab/Simulink,and its effectiveness was verified.When grid single/two phase short circuit fault occurs,the strategy can effectively suppress the DC side voltage and grid connected active power fluctuations,reduce the amplitude of the grid connected current,and it is better support system for low voltage ride through.