Optimization Framework for Weak Power Distribution Networks: A Case Analysis of Power System Rehabilitation in Afikpo Zone in Ebonyi State of Nigeria

This paper presents an optimization framework for rehabilitating weak, 33-bus radial power distribution networks in Afikpo Zone within the Enugu Electricity Distribution Company (EEDC) network in Ebonyi State, Nigeria, as a critical case study. The study investigates the engineering root causes of systemic grid collapse through a methodological framework that integrates physical structural audits with advanced computer-aided simulations using ETAP and MATLAB software. ETAP was utilized to execute Newton-Raphson load-flow simulations and short-circuit fault analyses, while MATLAB was deployed to model transient stability and voltage profile degradation across the network. The empirical and simulation results reveal that the network’s failure is primarily driven by its uncompensated 33kV radial feeder configuration, which induces severe I²R power losses and forces voltage profiles to drop far below the statutory ±5% tolerance limits. Simulation data highlight catastrophic thermal overloading at the central 7.5MVA injection substation, aggravated by malfunctioning protection relays and obsolete oil circuit breakers. Furthermore, field diagnostics confirm widespread dielectric insulation breakdown in local 11kV/0.415kV transformers caused by chronic moisture ingress and severe phase load imbalances. To mitigate these cascading failures, this paper proposes an engineering rehabilitation framework. The modeled interventions demonstrate that replacing weathered conductors with insulated aerial bundled cables, completing the Amasiri 33kV substation corridor to shorten radial path lengths, and implementing systematic consumer load balancing will drastically minimize losses and restore grid reliability. This assessment provides a scalable technical blueprint for optimizing weak distribution infrastructure in developing economies.