Refined power quality indices

Abstract

Major power quality indices such as total harmonic distortion, power factor, K-factor and others are presented, analysed and discussed. The limitations, deficiency and difficulty of practical application of these FFT-based indices in quantifying the quality of three-phase power systems are manifested. Modified versions of each index that avoid its unwanted drawbacks are suggested utilising the potential of wavelet multiresolution signal decomposition. A load nonlinearity indicator is proposed as a novel power quality index. Advantages of the new indices are highlighted and its performance in assessing power system quality compared with the traditional set of indices.