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中文摘要：
发现合于永久故障时三相重合闸时序对系统暂态电压稳定性有较大影响，以单负荷无穷大系统为例探讨其机理。分别在恒阻抗、恒电流和恒功率3种静态负荷模型以及感应电动机动态负荷模型下，考虑故障点位置变化，推导出交流线路从发生三相短路至三相断路器跳闸、三相重合于永久故障直到后加速三跳的整个过程中，负荷侧母线电压的解析表达式。通过比较2种重合时序下的负荷侧母线电压发现，在恒阻抗、恒电流及动态负荷模型下，由远离负荷的线路首端重合，可增大负荷侧母线电压，动态负荷模型下还可减小保护再次跳闸时的电动机转差率，有利于提高系统暂态电压稳定性；而在恒功率负荷模型下，重合时序受故障位置影响，推导出了影响重合时序的故障距离解析式。鉴于实际系统中运行方式变化，提出了离线计算与在线结合的实用三相重合时序整定策略，以提高系统暂态电压稳定性。对单负荷无穷大系统和2010年南方电网的仿真结果验证了其正确性和有效性。
英文摘要：
Larger effect of three-phase re-closure sequence on system＇s transient voltage stability when re-closing to permanent disturbance is discovered. A single load infinite bus system is taken as an example to discuss this mechanism. The transient process starts from a permanent fault occurred, then a three-phase breaker is tripped, then reclosed to permanent fault, till the three-phase breaker is tripped again. Load bus voltage transients of this process are calculated and the corresponding analytical expression is also derived. By comparing the bus voltage under the two re-closure sequences, it is discovered that under constant impedance load model, constant current load model, and dynamic load model, bus voltage can be increased by re-close to head terminal of transmission line and slip ratio can be decreased when breaker is tripped again, which is beneficial to transient voltage stability of the system; while under constant power load model, re-closure sequence depends on fault distance, and the corresponding analytic expression is derived. In view of the difficulties in solving it, a practical setting strategy by combining off-line calculation and on-line setting is proposed. The correctness and effectiveness of re-closure strategy is verified by simulation results in single load infinite bus system and 2010 Southern China power gird.
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