Measurement and analysis of harmonic distortion in power distribution systems

Power distribution systems often exhibit different harmonic behaviours at different locations. It is not usually possible to completely characterise the distortion at a particular site, however, due to insufficient data about the measured system and instrumentation inability to evaluate or register complete set of measurement quantities. In this paper existing power quality standards are analysed and new harmonic distortion indices are derived. A new index describing the total harmonic distortion in current measurements, TRD, is Suggested in order to simplify and standardise harmonic measurements. Another index representing the increase of harmonic voltage distortion with TRD, equivalent harmonic impedance z(eq), is proposed as an efficient way of characterising a particular site. The framework described here can be used to predict future harmonic behaviour at any previously measured point. Finally. extensive harmonic measurements of a real distribution system were performed to prove the usefulness of the proposed indices. (C) 2009 Elsevier B.V. All rights reserved.