不平衡电网电压下永磁直驱风力发电系统网侧变流器控制策略

A Control Strategy of the Grid-side Converter for Directly-driven Wind Turbine With PM Synchronous Generator Under Unbalanced Grid Voltage Level

建立了电网电压不平衡环境下永磁直驱风力发电机电网侧变流器的数学模型,分析了直流侧电压2倍频分量产生机理,讨论了并网电抗器上的功率波动对网侧变流器双电流控制策略的影响。为抑制不平衡电网电压下直流侧电压2倍频分量,在计及并网电抗器上功率波动的基础上,提出了一种基于正负序电压分别定向的双电流控制策略,并引入了并网电抗器上功率波动修正量对控制算法中的参考电流进行修正。仿真结果表明所提控制策略不仅能有效地控制正负序电流、抑制直流侧电压的2倍频分量,还能减少并网电流的谐波含量。

A mathematical model of the grid-side converter for directly-driven wind turbine with permanent magnet syn- chronous generator （PMSG） under unbalanced grid condi- tions is built, the formation mechanism of voltage double- frequency components on DC side is analyzed, and the influ- ence of power ripple of grid-connected reactor on dual cur- rent control is discussed. To suppress the voltage double-fre- quency component on DC side, an orientated dual current control strategy, which is based on positive and negative se- quence voltages respectively, is proposed by considering the power ripple on grid-connected reactor, and the correction of power ripple on grid-connected reactor is introduced to revise reference current in control algorithm. Simulation re- sults show that the proposed control strategy can not only ef- fectively control positive and negative sequence currents and depress voltage double-frequency component on DC side, but also can reduce harmonic component of grid-connected current.