Assessing the impact of unbalanced load on the technical losses in an lv distribution network

Abstract

Distribution network losses, specifically technical losses represent a substantial amount of energy and, consequently, a large cost that is often included in the tariffs structure. Unbalanced loading is one of the causes of technical losses. Uneven connection of single phase loads is a major cause for three-phase unbalance and a fundamental cause for active power losses, particularly in Low voltage (LV) networks. This project study analyzes the impact of load unbalance on LV distribution network losses. This report also presents a study aimed as showing some of the methods of dealing with unbalanced loading. A case study of five UMEME distribution transformers was considered based on the data collected from UMEME. From the data collected, the five distribution transformers were selected after analyzing the data to ensure that the transformers were significantly unbalanced. Technical losses for each transformer were determined through simulation. Losses due to unbalanced loading were also determined by rigorous power losses calculations using current flowing through the neutral conductor. The percentages of technical losses attributed to unbalanced loading were determined. All simulations were done in DIgSILENT software. Solutions to unbalanced loading were suggested and tested by simulation in DIgSILENT software. This study shows that technical losses increase as the level of imbalance increases and manually shifting loads from overloaded phase to underloaded phases actually helps in reducing the level of unbalanced loading and subsequently the losses due to unbalanced loading. It also shows that algorithms such as the Genetic algorithm can be helpful in achieving an optimum phase loading sequence for the distribution transformer.