Design of an Electrical Energy Monitoring System Using Branch Current Based State Estimation in Radial Distribution Networks

Abstract

Electric power distribution systems require reliable monitoring to estimate current and voltage conditions under limited measurement availability. This research presents an electrical energy monitoring system based on Branch Current Based State Estimation (BCBSE) with Weighted Least Squares (WLS) for a three-phase radial distribution network. Actual measurements and pseudo-measurements are integrated to improve network observability, while Phasor Measurement Unit (PMU) placement is optimized using Particle Swarm Optimization (PSO) with a limited number of PMU. The proposed approach is evaluated under low load, medium load, and high load conditions using current stabilized MAPE and voltage MAPE as performance metrics. The optimized PMU placement achieves current stabilized MAPE values of 8.780%, 10.921%, and 7.667% under low load, medium load, and high load conditions, respectively. Meanwhile, voltage estimation remains stable, with MAE below 1% for all loading conditions. Exhaustive search validation confirms that the PSO result provides the lowest overall estimation cost among the evaluated PMU placement combinations. These results indicate that the integration of BCBSE-WLS and PSO-based PMU placement improves current estimation accuracy and supports more reliable monitoring of radial distribution networks.