故障导致电力系统不可观情况下的故障定位方法

Fault Location Method when Power System Un-Observable Caused by Fault

故障发生后电网的拓扑结构发生变化,可能会造成电力系统失去可观性。现有的辨识方法忽略了这种特殊情况下对定位准确性的影响,而若能准确地辨识故障位置则可以在故障发生后采取保护策略,阻止故障的扩大。针对这一问题首先分析了在常规电网结构中不平衡电流的计算方法,研究了故障发生后不平衡电流与故障线路之间的关系。然后分析了几类可能的同步相量测量装置(phasor measurement unit,PMU)配置情况,研究了PMU配置位置与故障发生后的系统不可观性的关系,揭示了几种失去可观性情况下的不平衡电流值的变化规律。利用不平衡电流计算值反推故障位置的方法提出了故障定位方法,制定了故障定位流程。最后基于BPA仿真软件搭建了一个35节点的电力系统,分别在不同的PMU配置位置下仿真对比了定位效果。结果表明所提出的方法能够准确地定位故障。所提方法的适用于结合保护装置动作信息进行广域后备保护,并且扩充了短路故障定位的适用范围。

The topology of power grid will change when a failure occurs, which may cause the power system to lose its observability. Existing identification method ignores the influence of this special condition on accuracy of fanlt location. If the fault can be located ac- curately, the protection strategy will be taken after failure to prevent the expansion of the fault. In this paper, calculation method of unbalanced current in conventional power grid structure is analyzed, and the relationship between unbalanced current and fault line after fault is studied. Further, several possible phasor measurement unit （PMU） configurations are analyzed, the relationship between PMU configuration position and power system being not observable after fault is discussed, and the variation rule of the unbalanced current value under the condition of losing observability is revealed. By using the unbalanced current calculated value to derive the fault loca- tion, a fault location method is proposed, and a fault location process is developed. A 35-node power system is built with BPA simula- tion software to compare the location effect under different PMU configuration positions. Results show that the proposed method can accurately locate the fault. The proposed method is applicable to the wide-area backup protection with action information from protec- tion devices, and extends the application of short-circuit fault location.