Probabilistic analysis of harmonic currents in power systems

The application of probabilistic methods to harmonic distortion commenced in the late 60s and early 70s with simple analysis based on instantaneous values of current. Some shortcomings were noted in relation to the early methods of analysis: there was a lack of knowledge concerning the actual distributions for all but a limited number of loads; and the interrelationship between the different harmonic currents for a single load was recognised as complex. The methods used to evaluate the harmonic levels must account for the nonstationary nature. To model the nonstationary effects account must be taken of the variation of the harmonic current with time.