A global power quality index for aperiodic waveforms

The power system is undergoing dramatic change as deregulation occurs. Since customers have more choices power quality is becoming a bigger issue and now entering electricity supply contracts. In such cases power quality indices are important in characterizing the quality of the voltage waveform. This allows power quality to be specified in contracts and verified. Moreover this allows a quantitative comparison of the power quality between various systems, as well as the effect of various proposals on the power quality of a system. This paper introduces RMS error and normalised RMS error as global power quality indices and shows how they can be applied.