Research on the New Phase Selector Based on Impedance Measurement
CHEN Zhao-hui, HUANG Shao-feng , TAO Hui-liang , YANG Qi-xun(North China Electric Power University, Beijing 102206, China)(Beijing Sifang Automation Co LTD, Beijing 100085, China)
In order to solve the mal-operational problem of the traditional impedance based phase selector, a new method for phase selection in microprocessor-based protective relaying is presented. The relationship between the magnitude and phase angle of the fault impedance and the load impedance are used for comparison. Its response to a number of fault conditions such as high impedance ground fault or fault in weak infeed system are verified by the simulation tests. The results show that the new method is suitable for the fault phase selection element based on steady state fault component in the EHV line protective relaying.