Global Positioning System Application in Current Phase Comparison of Differential Protection Relay of Power Transmission Line

Abstract

This study simulates short-circuit current before a power transmission system is integrated into the system, so that the differential protection relays at both ends have current value and that current transducer transforms three-phase current to voltage value. Furthermore, a multi-function protection relay tester was used to obtain voltage waveform. The reference voltage using global positioning system synchronous time was compared with three-phase current waveform at both ends so as to obtain time difference. The current angle of various phases at both ends was calculated to compare whether the current angle difference between various phases at both ends was about 180°. The current phase comparison could be used to determine whether wiring is correct. The primary protection relay can synchronously operate when the line is integrated into the system.

Keywords:

• global positioning system
• differential protection relay
• current phase comparison multi-function protection relay tester