发现稳定裕度除了随线路上的故障位置单调增加、单调减小、凸状变化外,还可能呈现凹状分布的形态。通过扩展等面积准则(EEAC)理论揭示其机理,以解析方式得到稳定裕度随故障位置凹状变化的条件,并在多机系统的仿真中验证了稳定裕度随故障位置的异常变化形式。该现象的发现和剖析不但有利于深入理解电力系统暂态稳定性的物理本质,也对工程分析提出了新的注意点。
It is discovered that the transient stability degree may change with the fault location of a transmission line in a concave form, instead of commonly accepted monotonic increase, ~monotonic decrease or convex form. The mechanism of the concave change form is revealed by the extended equal area criterion (EEAC) theory and its analytical conditions are obtained for onemachine infinite-bus systems. Meanwhile, the abnormal form, which the transient stability margin varies with the fault location is verified in multi-machine systems by simulations. The discovery and investigation of this phenomenon not only contribute to a better understanding of the physical nature of the power system transient stability, but also present a new warning for the engineering analysis.