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=√(P ²+Q²+D²), 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_i) and total harmonic voltage (THD_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