Measurement-Based Characteristic Curves for Voltage Stability and Control at the Point of Interconnection of Wind Power Plants

In this paper, the measurement-based characteristic curves, reactive power–voltage ( $Q$ – $V$ ) curve and reactive power–active power–voltage ( $Q$ – $P$ – $V$ ) curve, are developed for voltage stability and control at the point of interconnection (POI) between a wind power plant (WPP) and a utility grid. The procedure to obtain an effective $Q$ – $V$ curve using the supervisory control and data acquisition (SCADA) measurement data is proposed. The SCADA data used in this paper were recorded in 2016 at the POI of a 27-MW WPP currently in operation in Newfoundland and Labrador (NL), Canada. Each $Q$ – $V$ curve is created for a particular month using the SCADA data corresponding to a very narrowly defined active power range, so the active power is considered constant as the conventional $Q$ – $V$ curve concept. The MATLAB curve fitting toolbox is used to realize the most fit mathematical equations for $Q$ – $V$ and $Q$ – $P$ – $V$ curves. The developed $Q$ – $V$ and $Q$ – $P$ – $V$ curves can be used for the data-driven voltage control for WPPs; and the $Q$ – $V$ curves can also be used for the voltage stability evaluation.