Assessment of Energy Losses in the High-voltage and Medium-voltage Networks of the National Electricity Company of NDjamena (Chad)

Electricity losses are a fundamental indicator of the performance of transmission and distribution networks. In developing countries, they represent a major technical, economic, and strategic challenge, as they directly affect the stability of the electricity system, the quality of service, and the profitability of operators. This study assesses technical and non-technical losses in the High Voltage A (HTA) and High Voltage B (HTB) networks of the National Electricity Company in NDjamena, the capital of Chad. The analysis is based on the use of energy injection data at source stations and billing data collected over a continuous 12-month period. The methodology adopted consists of comparing the energy injected into the networks with the energy actually billed to subscribers in order to determine the overall loss rate, then distinguishing between technical and non-technical losses. Technical losses are mainly related to physical phenomena inherent in the transmission and distribution of electricity, including Joule losses in conductors, losses in transformers, and load imbalances. Non-technical losses are mainly due to metering system failures, fraud, illegal connections, and meter reading errors. The results show that losses recorded on the HTB network remain relatively moderate, with an estimated rate of between 3% and 5%, which is in line with the standards generally observed for transmission networks. On the other hand, the HTA network has significantly higher losses, ranging from 15% to 20%. This difference can be explained by the length of the HTA feeders, the obsolescence of certain equipment, the overload of distribution transformers, and a sometimes insufficient power factor. The study also highlights the significant impact of non-technical losses, which contribute significantly to the overall energy imbalance. Based on these results, several technical and organizational recommendations are proposed. These include optimizing conductor sizing, compensating for reactive energy to improve the power factor, strengthening preventive maintenance programs, modernizing transformer stations, and deploying smart meters to reduce non-technical losses. Improving the overall efficiency of the electricity grid in NDjamena is therefore an essential lever for increasing the energy performance and economic viability of the national electricity sector.