With the recent advancements in power electronics for wind turbines, wind power plants (WPPs) have become valuable assets for reactive power support of bulk power systems. In this paper, we present a methodology to optimize the WPP's reactive power capability as seen from the point of common coupling (PCC). To this end, the proposed methodology determines the configuration of the tap-changing transformers within the WPP that maximizes the amount of reactive power the WPP can either consume or inject into the network, considering uncertain levels of wind power generation and voltage magnitude at the PCC. The optimized reactive power capability (ORPC) problem is initially formulated as a mixed-integer nonlinear programming (MINLP) model. Then, a set of efficient linearization techniques are used to obtain a mixed-integer linear programming (MILP) model that can be solved via off-the-shelf mathematical programming solvers. The results demonstrate that the proposed MILP model is a scalable, flexible and accurate method to maximize the reactive power capability of WPP as seen from the PCC.

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