TITLE:
Modeling and Analysis of Electrical Protection Systems: The Case of ZIZ Energie Mongo’s H61 Substations in the Sahelian Zone of Guéra (Chad) during the Rainy Season
AUTHORS:
Yacoub Nassian Nimir, Haroun Abba Laban, Moussa Ahmat, Mahamat Wadi
KEYWORDS:
MATLAB/Simulink, Lightning, ZnO Surge Arrester, H61 Substation, Distribution Network, ZIZ Energie de Mongo, Rainy Season, Sahelian Zone, Keraunic Level, Grounding
JOURNAL NAME:
Energy and Power Engineering,
Vol.18 No.11,
November
5,
2026
ABSTRACT: Mongo, the capital of the Guéra province, is located within the central Chadian massif, in the heart of the Sahel-Sudan belt. It lies between 12˚10'58''N and 18˚41'05''E, in a strategic climatic zone subject to the seasonal oscillations of the Intertropical Convergence Zone and, consequently, to climatic constraints. The rainy season extends from May/June to October, with annual precipitation ranging from 300 to 800 mm; the peak of the season occurs in July and August. In this region, lightning-induced overvoltages pose the most severe challenges for H61 transformer substations due to high lightning activity and humidity. These climatic factors compromise grid stability and expose overhead distribution substations to significant risks of insulation breakdown caused by atmospheric overvoltages. This study focuses on modeling a protection system for H61 overhead substations operated by the local electricity utility (ZIZ Énergie) in Mongo a Sahelian zone specifically during the rainy season. A key aspect of the analysis is examining the behavior of the H61 transformer both with and without ZnO (zinc oxide) surge arresters. The results demonstrate that, in the absence of protection (i.e., without ZnO surge arresters), lightning strikes cause severe damage to the H61 transformer, impairing its operation and potentially rendering it inoperable. Integrating surge arresters and ensuring they are positioned as close as possible to the transformer provides effective and adequate protection. Furthermore, this research provides a valuable decision-support tool for researchers and experts in the field of electrical protection. MATLAB/Simulink is used for this purpose.