为了实现有限PMU布局方式下的快速有效电网故障检测,研究了电网故障线路在线识别算法。根据PMU布局将电网划分为多个区域。分析了故障发生时流入故障区域的正序、负序和零序电流明显增大的特性,研究了基于边界PMU的故障区域搜索方法。基于虚拟节点构建了纯故障等值模型及其故障分量电压方程。利用一个区域的各边界节点电气量,构造故障分量电压的超定方程组,采用最小二乘法求解故障线路的故障点位置,准确检测故障区域内的故障线路。IEEE14节点系统上大量仿真实验验证了该算法的有效性,它不受故障位置、故障类型、过渡电阻的影响。仿真实验也表明了采用最小二乘法求解的故障点精度能够满足要求。
In order to detect power system fault using limited PMU quickly and effectively, a novel online fault detection algorithm is proposed. The power grid is divided into different zones by the placement strategy of limited PMUs. The character that the sum magnitudes of positive, negative and zero sequence currents entering one zone increase evidently is analyzed. An identification method of faulted zone is given. The pure fault equivalent model is constructed, as well as the fault component voltage equation based on virtual nodes. Using PMU electrical variables from boundary nodes of the zone, the fault component voltage over-determined equations are derived. The fault position of faulted line is obtained using the least square method. Then fault line in faulted zone is correctly detected. The effectiveness of proposed algorithm is illustrated by the simulation tests on IEEE 14-bus system. It is not affected by fault position, type and transition resistance. The fault position accuracy using least square method can meet the requirements.