Voltage Support Capacity Improvement for Wind Farms with Reactive Power Substitution Control

Abstract

Generally, voltage support at the point of common coupling (PCC) of a wind farm is achieved through centralized static var generators (SVGs). Since the reactive power requirements occupy their capacity in a steady state, the reactive power support capacity of the SVG is limited during high voltage ride through (HVRT) or low voltage ride through (LVRT). While wind turbines can provide voltage support in accordance with the grid code, their responses are usually delayed due to communication and transmission lags. To enhance the dynamic performance of wind farms during fault ride-through, a reactive power substitution (RPS) control strategy is proposed in this paper. In a steady state, this RPS control method preferentially utilizes the remaining capacity of wind turbines to substitute for the output of the SVG. Considering differences in terminal voltage characteristics and operating conditions, this RPS control method employs a particle swarm optimization (PSO) algorithm to ensure that wind turbines can provide their optimal reactive power support capacity. When the grid voltage swells or drops, the SVG has a sufficient reactive power reserve to support the grid quickly. This paper utilizes a regional power grid incorporating two wind farms connected to different buses as a case study to validate this RPS control strategy.