Examination of Loading and Grounding Characteristics for Three-Phase Four-Wire Multi-grounded Distribution System

In this study, the operational characteristics of a practical Taipower three-phase four-wire (3Φ4W) multi-grounded distribution system are investigated. Based on an actual feeder model, the analysis focuses on how unbalanced loading and grounding configurations affect the neutral current, neutral-to-ground voltage, and system power losses. Several load imbalance scenarios and grounding conditions are simulated, including variations in the neutral grounding impedance and number of grounding points. The results show that load imbalance has the most significant impact on the neutral line current and voltage increase. Voltages can exceed 100 V under severe conditions, and the combined neutral and ground path losses may account for over 34% of the total line losses. In contrast, grounding parameters largely determine the distribution of the ground leakage current. These findings provide engineering insight for improving the safety and performance of multi-grounded 3Φ4W systems under realistic operating conditions.