WAVELET-ANN APPROACH TO CLASSIFY CAPACITOR SWITCHING, LOAD SWITCHING AND LINE SWITCHING TRANSIENTS

With wide spread use of sensitive nonlinear electronic devices, electromagnetic transients are capable of degrading the quality of power. Utilities often switch the shunt capacitor banks to cope up with sagging voltage levels, thereby generating transients, which travel into the network of end users. Capacitor switching can cause over voltage, resonance and in advert tripping of Adjustable Speed Drives (ASD) and many other sensitive electronics devices. This paper presents a method to distinguish between transients arising out of isolated capacitor switching, back-to-back capacitor switching, load switching, line energization and line de-energization. The DWT of modal voltage signal is used to extract distinguishing features from the voltage waveform of these events. The detail coefficients for d1 and d5 level only, obtained from DWT are processed, mapped and given to Feed Forward ANN (FFANN) network, which accordingly classify the event. A real power system has been simulated in PSCAD/EMTDC with lines modeled using frequency dependant phase model.