Correlation‐based synchro‐check relay for power systems

Abstract

The synchronisation is a critical process in power system. When closing a circuit breaker (CB) between two energised parts of the power system, match voltages on both CB sides before closing must be verified. Non-synchronising conditions will result in a power system disturbance and equipment damage. The voltage magnitude, frequency and phase angle differences across the breaker must be closely monitored. In this study, the author suggests a synchro-check relay based on correlation concept. The correlation is considered a proper statistical method for estimating the similarity between electrical signals. The three-phase voltages and currents, measured from the two sub-systems, are used in the proposed technique to check match voltages during normal operation conditions. The synchroniser can operate online and function in automatic mode for electrical networks with different voltage levels. In addition, it can be used to supervise CB closing for avoiding an incorrect operation. Two parts of a 19.57 kV/500 kV power system with real parameters are simulated using alternative transients program (ATP) software and MATLAB package to examine the suggested algorithm under different operating conditions. The simulation results show that the proposed approach is relatively simple, reliable, efficient and very promising in applications to generation plants and substation automation systems.