Classification of fault originated transients in high voltage network using DWT–PCA approach

Abstract

The analysis of electromagnetic transients associated with an abnormal condition in a power system has always been fundamental in describing and then correcting the cause of the condition. However, with wide spread use of sensitive nonlinear electronic devices these 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 to ground fault, double line to ground fault, line to line fault, triple line fault, line energization and line de-energization. The Discrete Wavelet Transform (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 PCA network, which accordingly classify the event. A real power system has been simulated in PSCAD/EMTDC with lines modeled using frequency dependant phase model.