采用双端量的高压输电线路选相元件

Transmission Line Phase Selector of Measurements at Two Terminals

为提高选相元件的性能,探讨了一种双端量的新型选相元件并进行了仿真研究。线路外部故障时的差动电流、差动电压满足电容模型,故选取相电压差、相电流差作为线模量,用时域中的短数据窗分别计算了3个线模量的电容模型误差。若为单相故障,则健全相线模的电容模型误差恒为零,故障相线模的电容模型误差远大于零;若为多相故障,则3个线模量的电容模型误差都远大于零。理论分析指出,该选相元件不受系统振荡及正负序阻抗不等的影响,无需提取突变量却具有突变量选相的优点,原理上不受长线分布电容电流和暂态分量的影响,在线路两端的灵敏度一样,动作可靠快速。ATP仿真实验表明,新原理不仅适用于简单故障,对发展性故障、长线高阻接地故障都能于12 ms内动作。

The difference of phase-to-phase current and voltage is selected as modules,so the capacitance model error of the three modules can be calculated using short data-window on the time domain.When the internal single phase earth fault occurs,the model error of the modules of two sound phases is zero,and errors of other modules are much remarkable.When the internal phase-to-phase fault occurs,errors of all the modules are large.Consequently,a novel phase selector of simple logic procedure and the same sensitivity at both terminals is presented.Theoretic analysis demonstrates that the new phase selector unnecessary to extract incremental components has the high sensitivity as the incremental-components phase selector,and it is able to work well in the system with unequal impedance of positive and negative sequence even during the power oscillation.ATP simulation tests show that the new element can operate correctly in 12 ms even for the developing faults and the high resistance earth fault in the end of the long transmission line.