Indices for assessing harmonic distortion from power quality measurements: definitions and benchmark data

For many years, electricity distribution companies have used sustained interruption indices as indicators of the reliability of service provided on their systems. Today, however, many electricity consumers are adversely affected by more subtle voltage disturbances such as harmonic distortion. In response to the increased sensitivity of end-use equipment, many utilities are implementing extensive monitoring systems to assess service quality levels. Such monitoring systems yield massive databases of service quality data. This paper presents indices developed to quantify system service quality with respect to measured harmonic distortion levels. Example benchmark values for the indices are calculated using data from a national distribution power quality data collection project.