Real-time detection of voltage sags based on wavelet transform

This paper presents a wavelet-based method for real-time detection of voltage sags in transmission lines. The wavelet coefficient energies of the phase voltages and currents are used for real-time detection of the transients at both beginning and end times of voltage sags. On the other hand, the voltage sags are identified in real-time by means of the approximation coefficient energy analysis. The voltage sag diagnosis method was evaluated by using the Real Time Digital Simulation (RTDS).