Power quality improvement utilizing neutral current in distribution systems

Summary Power distribution feeders carry a high neutral current than expected due to the increased integration of low carbon technologies. The number of small photovoltaic units and electric vehicle chargers in the system has increased. These unpredictable, nonlinear, single‐phase sources and loads are difficult to balance among phases. The nonlinear power electronic devices produce harmonics. Phase unbalance and harmonics cause high neutral current, resulting in more neutral to earth voltage (NEV) and neutral heating. Neutral line grounding is critical in earth fault protection. In this article, a new neutral line grounding practice is proposed that can improve power quality in three phase four wire distribution systems, without installing any additional equipment. The presence of neutral current and mutual coupling between the lines is utilized to reduce voltage regulation, unbalance, and harmonics. The earth fault current and NEV is also reduced, but with a slight increase in line loss. The method is verified by an analysis conducted in the IEEE low voltage test feeder, using OpenDSS, a distribution system simulation tool developed by EPRI. Presenting a new neutral line grounding practice for improving power quality in three phase four wire distribution systems without installing any additional equipment. The presence of neutral current and electromagnetic coupling between the lines is utilized to reduce voltage regulation, unbalance, and harmonics. The single line to ground‐fault current and neutral to earth voltage is also reduced, but with a slight increase in line loss.