弱电网下考虑锁相环影响的双馈风电机组复合解耦控制策略

COMPOUND DECOUPLING CONTROL STRATEGY FOR DFIG CONSIDERING PLL IN WEAK GRIDS

在风力发电并网容量快速增长的同时,并网点的短路比同步降低,基于锁相环同步的双馈风电机组面临稳定裕度不足及功率耦合加剧的问题。该文通过构建双馈风电机组在弱电网下的小信号模型,探究锁相环对于电流控制的影响回路,降低系统稳定裕度的机理。进一步提出考虑锁相环影响的复合解耦控制策略,有效提升了双馈风电机组在弱电网下的稳定运行能力。该文通过仿真及实验验证了所提策略的有效性。

With the rapid growth of the grid-connected capacity of wind power generation,the equivalent short-circuit ratio(SCR)of point of common coupling(PCC)decreases rapidly.The doubly-fed induction generator(DFIG)based on phase-locked loop(PLL)synchronization are faced with the problems of insufficient stability margin and intensified power coupling.By constructing a small signal model of DFIG in weak grids,this paper explores the mechanism of PLL’s influencing on current control and the reducing the system stability margin.Furthermore,a compound decoupling control strategy considering the effect of PLL is proposed,which effectively improves the stable operation capability of DFIG in weak grids.The effectiveness of the proposed strategy is verified by simulation and experiment.