LAUSR

At present, systems for wind power transmission by ultra-high voltage direct current (UHVDC) and ultra-high voltage alternating current (UHVAC) have been constructed and are operating in China. The installed capacity of the doubly fed induction generator (DFIG) and the rated power of the UHVDC in a system involving wind power transmission by the UHVDC/UHVAC (WIND-UHVDC/AC) are very large, and the active power recovery rates of the DFIG and UHVDC after a short-circuit fault is cleared will seriously affect the rotor angle stability of the sending-end system. Therefore, it is significant to analyze the active power recovery rates of the DFIG and UHVDC for the safe operation of the WIND-UHVDC/AC system. First, the influence of the active power of the DFIG and UHVDC on the electrical power of the synchronous generator (SG) in the sending-end system is deduced mathematically. Second, the impact of the active power recovery rates of the DFIG and UHVDC on the deceleration areas of the SG are analyzed, respectively, and the effects of the variation in the equivalent internal reactance of the SG on the leftward shift and downward shift of the electrical power curve are studied. Then, the mechanism of the interactive influence of the active power recovery rates of the DFIG and UHVDC on the rotor angle stability is further analyzed. Finally, the theoretical analysis is validated using a typical WIND-UHVDC/AC system and an actual WIND-UHVDC/AC system in China’s Northwest Power Grid. The analysis in this paper provides a theoretical foundation and a reference for the stability control strategy for the WIND-UHVDC/AC systems.