AN INVESTIGATION OF HARMONICS ATTENUATION AND DIVERSITY AMONG DISTRIBUTED SINGLE-PHASE POWER ELECTRONIC LOADS

Widely distributed single-phase power electronic loads are an increasi ngly important source of harmonics in power distribution systems. The objective of this paper is to investigate the cumulative harmonic curr ent characteristics of a large number of such loads. A complete analyt ical model for the most common load type is derived. This model is the n used to investigate the impact of 1) interaction due to a shared sou rce impedance, 2) variation in power level, and 3) variations in circu it parameters, on individual and cumulative current harmonics. The key findings of the paper are that diversity and attenuation are very imp ortant factors in predicting the behavior of distributed single-phase power electronic loads; especially for the higher-order harmonics, and that due to these two factors, the commonly-used fixed current inject ion method, using arithmetic sums of harmonic current magnitudes, dan significantly overestimate the cumulative harmonic currents produced b y these loads.