Power quality indices for aperiodic voltages and currents

This paper addresses the subject of transient electric power quality problems. The quantification of power quality in terms of simple indices such as total harmonic distortion and other measures is revisited in terms of the windowed Fourier transform. This transform is a short term Fourier transform evaluated over a time window. The result is a set of new power quality indices which collapse to the familiar forms for the cases of periodic steady state, but which capture transient amplitudes for nonsteady state applications. Applications are suggested