一种基于功率增量的高压线路保护选相元件

准确有效的选相元件是高压输电线路实现选相跳闸及采用自动重合闸的前提.在给出功率增量的概念和被保护线路每相功率损耗增量计算公式的基础上提出了一种基于被保护高压线路功率损耗增量的高压线路保护选相新原理,应用于保护启动后第一次选相的选相元件.根据故障相功率损耗增量远大于健全相的特征,再结合零序电流辅助判据来得到选相结果和故障类型.该选相元件原理简单、不受系统参数变化的影响,弱电源侧具有相同的灵敏度,并具有很强的耐过渡电阻能力.EMTDC仿真结果表明,该选相元件能有效可靠地选出故障相,满足现场运行要求.

A Fault Phase Selector for HV Transmission Line Protective Relaying Based on Power Increment

The exact and effective fault phase selector is the premise for high voltage line to realize correctly tripping and autoreclosure. The power increment concept is to be defined and the formula to calculate the power increment of per phase is presented, furthermore, a new principle for fault phase selection based on power increment is to be proposed, and the principle is to be applied in the first phase selection after protection startup. Based on the character for the power increment of the fault phase to be much greater than that of the healthy phase. The principle can derive the result of phase selection and the fault type by combining assistant criterion of zero sequence current. The fault phase selector has a simple principle and is not to be effected by the change of system parameter, and it has equal sensitivity in the side for weak power, furthermore, the selector proposed has excellent performance under high-resistance fault conditions. The results of EMTDC( Electromagnetic Transients Simulation Engine Including DC ) simulations show that the selector can discriminate fault phases reliably and meet the requirement of phase-selection in real environment.