Commentary on various formulations of distortion power D

In a circuit where the load is nonlinear or the source has nonsinusoidal wave forms the apparent power is defined as S=/spl radic/(P/sup 2/+Q/sup 2/+D/sup 2/), where various formulations of distortion power D are reviewed. It is well known that the distortion power D is generated by the cross products of voltage and current harmonics of different frequencies. Accurate experiments are performed to measure the distortion power for a great variety of nonlinear load conditions of a 25 kVA transformer for a range of total harmonic current (THD/sub i/) and total harmonic voltage (THD/sub v/) distortions. The computed distortion power D as a function of voltage and current harmonics of unlike frequencies is validated by measurements: one concludes that a proper interpretation of Budeanu's definition is correct and agrees with measured results.