变速恒频风电系统应对电网故障的保护电路分析

新的电网规则要求风力发电系统具有低电压穿越能力，基于双馈感应发电机的双馈型风电系统和基于永磁同步发电机的直驱型系统作为主流变速恒频风能变换系统，增加保护电路后，可以极大地提高其故障穿越能力。基于国内外对变速恒频风电系统保护电路的分析和总结，对各种类型的保护电路进行了分类，对其工作原理和实现方法进行了详细说明，并讨论了各自的优缺点。增加保护电路可以使变速恒频风电系统在电网故障发生时，保持与电网的连接，当故障消除后，快速恢复正常运行，从而极大地提高风电系统的可用型、可靠性和市场竞争力。

Analysis on Protection Circuits suitable for VSCF-WECS to Cope with Grid Faults

The requirement is presented by new grid codes that wind energy conversion system (WECS) should have capability of lowvoltage ride through (LVRT), by adding protection circuits, the fault ride through capability of mainstream variable-speed constant-frequency(VSCF) WECS which includes doubly-fed induction generator (DFIG) based doubly-fed system and permanent magnet synchronous generator(PMSG) based direct-drive system can be considerably increased. Based on the summary of protection circuits suitable for VSCF-WECS athome and abroad, the different types of protection circuits are classified, the working principle and realization are explained in detail, then theadvantage and disadvantage of each method is discussed. Adding protection circuits can make the VSCF-WECS keep connected with grid duringfaults and recover normal operation fast after fault clearance, which will greatly improve the availability, reliability and market competition of WECS.