Experimental Evaluation of Unbalance and Distortion Indicators in Three-Phase Systems with Neutral

The characterization of three-phase systems with neutral under unbalanced operation in the presence of waveform distortion is a key aspect in the power quality studies. This paper presents the application to a number of real cases of a unified framework providing a set of synthetic indicators capable to explain the individual effects of unbalance and harmonic distortion. The use of specific indicators extending the notion of total harmonic distortion to the case of unbalanced systems, and the notion of unbalance to the systems with distorted waveforms is illustrated and discussed on various sets of data gathered from real-time measurements on office and laboratory feeders and on a photovoltaic system.