Small and large disturbances in power system may sometimes lead to sustained oscillation in three-phase power, often termed as ‘power swing’ in the literature. Power swing is a balanced phenomenon and may be indistinguishable from a three-phase fault. Transmission lines being protected by distance relays may be incorrectly de-energized because of a power swing. So, three-phase faults should be discriminated from power swing with high reliability and dependability. In this study, a novel symmetrical fault detection technique has been proposed with dual use line relays for the first time. The proposed algorithm has been verified for a large number of fault scenarios including series compensated lines with single machine infinite bus and western system coordinating council-9 bus system. It has been seen that the proposed algorithm is giving fast detection of three-phase faults during power swing with high accuracy.

电力系统的大小扰动有时可能导致三相功率持续振荡，在文献中通常称为“功率摆幅”。功率摆幅是一种平衡现象，可能无法与三相故障区分开。受功率继电器保护的传输线可能会错误地断电。因此，应该以高可靠性和可靠性将三相故障与功率波动区分开。在这项研究中，首次提出了一种新的对称故障检测技术，该技术具有两用线路继电器。所提出的算法已针对包括单机无限母线串联补偿线路和西方系统协调委员会9母线系统在内的大量故障场景进行了验证。