Fault characteristics and protection adaptability analysis in VSC‐HVDC‐connected offshore wind farm integration system

Abstract

Due to different fault ride through controls of both the wind farm and the voltage‐source converter high‐voltage alternating current (VSC‐HVDC) converters, the offshore wind farms that are connected to the power system through VSC‐HVDCs have unique fault transients. During a fault on AC side transmission lines, the wind farm and the VSC‐HVDC together provide faulted current, whose amplitude and phase will be decided by their different control strategies collectively. The fault transients are different from those in the traditional AC grid. Thus, the performance of traditional protection will be affected. In this study, the AC fault current expression is deduced, while the influencing factors on the current's amplitude and phase are analysed in detail. Based on these characteristics, the performance of distance relays under the grid side fault of the VSC‐HVDC‐connected offshore wind farm integration system is evaluated. Simulations based on PSCAD have verified the theoretical analysis.