直流输电系统紧急停运方式对系统过电压的影响

基于云广±800kv特高压直流输电工程的参数，研究了直流输电系统在最高电位换流变阀侧对地故障、逆变站闭锁而旁通对未解锁、逆变站交流电源丢失等三种故障工况下紧急停运方式对系统暂态过电压的影响，紧急停运方式包括移相、投旁通对闭锁和直接闭锁。分析结果表明，对于整流站换流变阀侧以及直流线路故障而言，采取故障后移相方式与直接闭锁相比可以更好地降低阀上的过电压；对于逆变站意外闭锁类型的故障，整流站5ms内移相的紧急停机策略可以显著降低逆变站极线上的过电压水平；逆变侧交流系统严重故障时，逆变站10ms内投旁通对的紧急停机策略可以最大限度降低高端换流变压器阀侧过电压水平。

Influence of the ESOF Strategy on HVDC System Overvoltage

Based on the technical parameters of Yunnan-Guangdong ±800 kV UHVDC project, the influences of the three kinds of ESOF strategy, named with the force retard, blocking with bypass pair and blocking without bypass pair, are evaluated on DC transient overvoltage. Three types of fault, including earth fault between converter transformer valve side to earth, blocking inverter without bypass pairs and loss of AC network in the inverter side, are chosed. The simulation results show that compared with blocking without bypass pair, force retard strategy after fault could better limit the overvoltage level of valve under the condition of converter transformer valve side fault and DC line faults in rectifier station. For accidental blocking type faults in inverter station, the force retard within 5 ms in rectifier station could significantly reduce the overvoltage level of DC line equipments installed in inverter station. For serious faults accured with AC system in inverter station side, the blocking with bypass pair within 10 ms after faults in inverter station could effectively limit the overvoltage level at the valve-side of Highest Potential Converter Transformer.