Small-signal Stability of Type 4 Wind Generators as Affected by the Bandwidth of Current and PLL Controllers

This paper investigates the small-signal stability of type 4 wind generators as affected by the bandwidth of current and phase-locked loop (PLL) controllers. Using eigenvalue and participation factor analysis, this paper shows that high frequency dynamics may become unstable if the bandwidth of the current controllers of the power electronic converters is high. It has also been found that the bandwidth of the PLL control should be a small fraction of the bandwidth of the current controllers.