Considerations on Current and Voltage Unbalance of Nonlinear Loads in Residential and Educational Sectors

Abstract

Most often, electrical consumers in the residential and educational sectors are different from industrial electrical consumers. Whereas the vast majority of industrial electrical consumers are low-voltage, three-phase (with three or four wires), electrical consumers in the residential and educational sectors are low-voltage, single-phase. However, in practice, electrical consumers in the residential and educational sectors are in large numbers. Usually, current and voltage unbalances are lower in the industrial sector compared to the residential and educational sectors, where there are a large number of low-voltage, single-phase consumers that are connected/disconnected in an uncontrollable way and that need to be wired and balanced on each phase of power transformers from power substations. The purpose of this paper is to present the results of electrical balance and improve the power factor in the power substation from residential and educational sectors. The paper investigates the current and voltage unbalance of nonlinear con sumers in the residential and educational sectors. For this purpose, we performed measurements in the laboratory and the power substation to investigate the unbalance in the three-phase system. Laboratory measurements were made in the unbalanced operation of the single-phase electrical consumers connected at three-phase system. The measurements from power substation were carried out after the electrical consumers were uniformly spread among the three phases from the low-voltage power network, on two different days: a workday and a weekend day. The current and apparent power unbalance were reduced and the power factor was improved using the capacitive single-phase electric consumers (e.g., personal computers, which are in large numbers in such sectors) evenly across the phases.