Pitfalls of electric power quality indices

Several indices are in common use for the quantification of electric power quality. These indices are convenient for condensing complex time and frequency domain waveform phenomena into a number. However, a variety of commonly encountered circumstances are not readily accommodated (e.g. quasiperiodic and aperiodic signal components and noninteger multiples of the power frequency). Also, the power acceptability curves have been used as convenient measures of power quality and these curves do not capture three-phase detail of power quality problems. In this paper, the general subject of pitfalls of power quality indices is discussed and suggestions for alleviating these problems are made.