COMPOUND DECOUPLING CONTROL STRATEGY FOR DFIG CONSIDERING PLL IN WEAK GRIDS
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.
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