双极MMC-HVDC系统故障限流及换流器快速重启策略研究

发布时间：2018-03-28 05:07

本文选题：模块化多电平换流器直流输电　切入点：真双极系统　出处：《中国电机工程学报》2017年S1期

【摘要】：随着模块化多电平换流器直流输电(modular multilevel converter based HVDC,MMC-HVDC)的快速发展,远距离大容量架空线直流输电系统随之出现。相比于电缆线路,架空线输电易发生短路、闪络等瞬时故障,必须采取相应措施限制故障电流,避免系统停运。针对架空线真双极MMC-HVDC系统,分别从交流系统和换流阀的角度分析架空线路单极接地故障的等值电路模型和故障特性,推导故障电流的解析表达式。提出了一种新型故障限流模块,可有效抑制闭锁后短路电流幅值。依靠该限流模块的限流能力,设计了换流站快速重启策略。仿真结果证明,该限流方案可有效限制桥臂电流的大小及上升速率,消除系统交流侧及换流器内部续流二极管的过流危害,减小直流断路器的动作难度,加速故障极换流站重启,减少系统停运时间。
[Abstract]:With the rapid development of modularized multilevel converter based HVDC (HVDCC), a large capacity overhead HVDC transmission system with long distance has appeared. Compared with cable lines, overhead transmission lines are prone to short-circuit, flashover and other transient faults. The corresponding measures must be taken to limit the fault current and avoid the outage of the system. In view of the true bipolar MMC-HVDC system of overhead line, the equivalent circuit model and fault characteristics of the single-pole grounding fault of overhead line are analyzed from the angle of AC system and commutation valve, respectively. An analytical expression of fault current is derived. A novel fault current limiting module is proposed, which can effectively suppress the amplitude of short circuit current after locking. Depending on the current limiting capacity of the current limiting module, a fast restart strategy for converter station is designed. The current limiting scheme can effectively limit the current size and rise rate of the bridge arm, eliminate the overcurrent damage of the AC side of the system and the recurrent diode inside the converter, reduce the difficulty of DC circuit breaker operation, and accelerate the restart of the fault pole converter station. Reduce system outage time.
【作者单位】：新能源电力系统国家重点实验室(华北电力大学);电网安全与节能国家重点实验室(中国电力科学研究院);
【基金】：国家电网公司科技项目(±500k V柔性直流电网对交流电网保护影响研究)~~
【分类号】：TM46;TM721.1

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