发现合于永久故障时,三相重合闸时序对系统暂态稳定性有较大的影响,以单机无穷大系统为例探讨其机理.考虑故障点位置变化.计算分析了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发电机至无穷大系统间的等值电抗,进而推导出系统电磁功率的解析表达式.由此发现合于永久故障时,系统复合序网的构成与连接、系统转移电抗及电磁功率幅值均取决于重合时序. 利用等面积法则从机理上剖析了三相重合时序对系统功角稳定性的影响.并据此提出了由等值电抗较小一侧首先重合的策略.鉴于多机系统中转移电抗求取面临一定困难,提出了离线计算与在线整定相结合的实用整定策略,仿真结果表明该策略正确、有效.%It is discovered that,the three-phase reclosing sequence has larger effect on system transient stability during the reclose to permanent fault. Single generator infinite bus system is taken as an example to discuss its mechanism. By calculating the equivalent reactance between generator and infinite-bus during the whole process from the occurrence of permanent fault,the three-phase breaker trip,the reclose to permanent fault,until the three phase breaker re-trip,the analytic expression of system electromagnetic power is derived. It is pointed out that,the compound sequence network,system transferring impedance and electromagnetic power depend upon the reclosing sequence. By changing the fault point position, influence of three-phase rnreclosing sequence on system power angle stability is elaborated in theory according to the equal area criterion, based on which,the three-phase reclosing sequence of "the side with less reactance first" is proposed to enhance system power angle stability. As it is difficult to obtain the transferring impedance of multi-generator system,a practical method combining off-line calculation and on-line setting is proposed. Simulation results show its correctness and effectiveness.
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