Accuracy of Voltage Unbalance Source Assessment in Three-Phase Three-Wire Electrical Networks

The power quality and related losses are topical problems in modern power engineering. There is a need to identify disturbing sources and assess their impact onto power quality in a point of evaluation on the basis of online measurements. The paper describes the accuracy of a brand new method for the assessment of voltage unbalance emissions in three-phase three-wire networks. Although power supply usually relies on the four-wire grids, the medium-voltage and maritime networks are based on the three-wire configuration. The modern techniques assessing voltage unbalance emission may generally be applied only to the cases with a single dominating emission or need invasive tests. The paper proposes a way to assess voltage unbalance emission from multiple sources by means of voltage and current measurements in a single point of evaluation and data about network configuration and component parameters. The paper describes the method in general terms and demonstrates high accuracy of the proposed solution as regards a methodological error and an impact of input data uncertainty.