一种新的高压线路振荡选相元件

提出了一种基于阻抗相对变化的高压线路保护选相新原理,用作振荡期间的选相元件.对接地故障,利用零序、负序电流之间相位差进行分区,每个分区包括某相单相接地和另外两相短路接地两种故障,根据故障环上的测量阻抗为一恒定数值,而非故障环上的测量阻抗随振荡变化这一特征,来得到选相结果.本元件提高了振荡中不对称接地故障的选相速度,不受系统运行方式和分支系数的影响,且易于实现,在现有的微机保护装置中可以直接使用.动模数据仿真表明,新选相元件具有较快的选相速度,文中算例可以在60 ms内选出故障相.

New Fault Phase Selector for High Voltage Transmission Line Protective Relaying During Power Swing

Based on the relative variation of impedance during power swing, a novel phase selector for high voltage transmission lines is proposed. When a grounding fault occurs, the fault is divided into three regions according to the phase-angle between the zero sequence and negative sequence components of the current, and each region contains one kind of single-phase-to-ground fault and the other kind of other two phase-to-phase-with-ground fault. Aiming at the characteristic that the measured impedance remains constant in faulty phase and variable in sound phase, the fault phase can be selected. The proposed phase selector enables to select the fault phase quickly during power swing, and different system cases have no effect on the selector. The performance of the proposed method is evaluated with the data created by dynamic model system, and the results show that the selector is able to identify fault phases within 60 ms.