Wavelet Analysis of Voltage Disturbances for Power Quality Applications

Abstract

This paper addresses the subject of stationary and non-stationary voltage disturbance problems in electric power system. The modified binary-tree wavelet decomposition technique with an appropriate wavelet filter is introduced as a powerful tool for detecting, classifying, and quantifying the voltage disturbances. Power quality (PQ) indices in terms of total rms, rms of individual frequency bands, duration of disturbance, and their dependent quantities such as voltage magnitude of disturbance and harmonic distortion can be measured directly from the wavelet transform coefficients. The proposed technique is simple, provides accurate value of PQ indices, and enables to discriminate among the type of similar voltage disturbance events. The proposed technique is validated by its application to various disturbance data and the measurement results, such as rms and harmonic distortion, are further compared with those obtained from the time domain and frequency domain methods.