Distributed Online Voltage Control for Wind Farms Using Generalized Fast Dual Ascent

This paper considers the voltage control problem in wind farms, with the goals of maintaining feasible voltage profile and adequate reactive power (VAR) reserves by coordinating the reactive power outputs of wind turbines (WTs) and static synchronous compensators (STATCOMs). Rather than a conventional centralized and offline fashion, we propose a distributed online voltage control scheme based on dual decomposition. First, the optimal voltage control problem is formulated based on the branch flow model. Then, thanks to the sparsity of the constraints in this problem, a distributed solution framework is developed based on the dual decomposition and its online implementation is achieved through voltage feedback. To pursue fast convergence of the distributed algorithm and consequently facilitate the online implementation, the fast gradient method is generalized and then applied to solve the dual problem. The effectiveness of the proposed voltage control scheme is numerically validated under both static and dynamic cases.