A Hierarchical Voltage Control Scheme for Wind Power Plants Through Enhanced Reactive Power Support

To maximize reactive power support from a wind power plant (WPP) and maintain power factor at the point of interconnection (POI) within acceptable limits, a novel hierarchical voltage control scheme consisting of a central WPP controller and a local wind turbine generator (WTG) controller is proposed in this article, and both controllers are operated in voltage control mode. When a voltage deviation is detected, if it is within the normal range, the central WPP controller turns on the integrated power factor controller to regulate the power factor at the POI. If the voltage deviation exceeds the normal range, the local WTG controller relies on the adaptive droop coefficient and the adaptive proportional setpoint weight-based rotor side converter controller to push the WTG toward its maximum reactive power limit to provide reactive power compensation during contingencies. For accurate estimation of the maximum reactive power capability of a WTG, a comprehensive model with various limiting factors is used. The proposed controllers are equipped with a memory, which ensures continuous operation during a communication failure. The proposed control scheme is validated by case and sensitivity studies using a practical WPP currently in operation in Newfoundland, Canada. It shows excellent performance when compared with the two existing methods.