高压线路保护选相元件的改进

相间故障时,弧光电压Ucos(ψ)的值较小;单相故障时,三个相间Ucos(ψ)的计算值都较大,根据这个特点,结合突变量选相元件和序分量选相元件提出了新的选相方法.新方法解决了线路发生单相故障时保护误跳三相的问题,动模数据仿真验证了新方法的准确性和有效性.

New Method to Improve the Performance of HV Transmission Line Protective Relaying Phase Selector

The cosine relay of phases fault at the fault point are lower than a threshold, and for single-phase-to-ground fault, the values of three are usually high, and combine with the power frequency component variation phase selector and the sequence component phase selector, a new method to select the faulted phase or phases is presented in this paper. The new method can solve the problem which the protective relay may trip three phases under singlephase-to-ground-fault condition.The performance of the new method was evaluated with data created by dynamic system, and the result show that the selector can determine faulted phase or phases correctly.