一种窄线间距平行双回线的单端电流选相原理

A faulted phase selection scheme for parallel lines with narrow line-to-line distance using double lines' one-terminal currents

窄线间距平行双回线的线间互感明显,某些故障情况下会影响传统保护的正确动作,并且其上可能的故障类型繁多,利用传统单端单回线电气量难以可靠选相。论文研究了此类双回线线间互感大小与相间互感接近的特点对故障下线路单端各相序电流的影响,根据其故障电流的特征提出了一种新的单端电流选相原理。该原理利用单端6个相序电流的故障分量进行选相,先通过同名相和电流选定故障相别,再比较各故障相的同名相电流选出具体的故障相序。可对平行双回线的各种单回线和跨线短路故障进行选相,选相原理简单,逻辑清晰可靠,且不受负荷电流影响。ATP-EMTP仿真结果表明,该方法能够对窄线间距双回线80%范围的单回线及跨线故障的可靠选相,可作为保护I段的选相判据。

For there is obvious coupling of lines on parallel lines with narrow line-to-line distance, in certain fault case the traditional protection device will act by mistake. Moreover, the types of possible fault are of great variety, so the phase selectors using single line＇s one-terminal currents can not work well. The effect to one-terminal phase lines＇ currents caused by the character that the coupling of lines nearly equal to that of phases on this kind of parallel lines has been researched, and a new fault phase selection scheme using double lines＇ one-terminal currents has been proposed based on the fault currents＇ character. The proposed scheme works by using the 6 one-terminal phase-line currents＇ fault components. Via using 3 one-terminal same-name-phases＇ sum-currents, the fault same-name-phase can be picked out firstly. Then, via synthetically comparing same-name-phase currents＇ fault components, the fault phase-lines can be i- dentified. The scheme is simple, reliable and is not influenced by the load current. Under either single-line fault or interline fault, the fault phase-line or phase-lines can be selected out reliably by the proposed scheme. Simulation results via ATP-EMTP show that the new scheme can give reliable phase selection when the fault happens at the near side of parallel lines with a length range of 80 % , therefore can be used as a selection criterion for the zone-I protection.