Flexible IQ-V Scheme of a DFIG for Rapid Voltage Regulation of a Wind Power Plant

This paper proposes a flexible reactive current-to-voltage (IQ-V) scheme of a doubly-fed induction generator (DFIG) for the rapid voltage regulation of a wind power plant (WPP). In the proposed scheme, the WPP controller dispatches different voltage set points to the DFIGs depending on their rotor voltage margins. The DFIGs inject different reactive power with the flexible IQ-V schemes implemented in the rotor-side and grid-side converters. The IQ-V characteristic, which consists of the gain and width of a linear band and IQ capability, varies with time depending on the IQ capability of the converters and a voltage dip at the point of interconnection (POI). To increase the IQ capability during a fault, the active current is reduced in proportion to a voltage dip. If the IQ capability and/or the POI voltage dip are large, the IQ-V gain is set to be high, thereby providing rapid voltage regulation. To avoid an overvoltage after the fault clearance, a rapid IQ reduction scheme is implemented in the WPP and DFIG controllers. The performance of the proposed flexible scheme was verified under scenarios with various disturbances. The proposed scheme can help increase wind power penetration without jeopardizing voltage stability.