Optimization of a Medium-Voltage Distribution Network via Photovoltaic Integration: A Case Study of the Liouesso MT Grid

This study rigorously investigates the technical implications of integrating a 3 MW photovoltaic (PV) power plant into a real-world medium-voltage (MT) distribution network located in Liouesso, Republic of Congo. The targeted grid is characterized by a semi-urban infrastructure with limited dynamic compensation capabilities and frequent critical undervoltage conditions. Unlike many studies that rely on theoretical models or synthetic datasets, this research is grounded in actual operational measurements (load profiles, nodal voltages) and high-fidelity dynamic simulations performed using the PSAT toolbox within the MATLAB environment. Two operating scenarios are evaluated: the baseline network performance without PV injection, and a modified configuration including active solar power injection at a strategically selected node (Bus 18). The results show that such controlled integration not only improves the voltage profile eliminating undervoltages below 0.95 p.u. but also significantly reduces active line losses (by 15 to 20 %), all while complying with international power quality standards such as IEC 61000-4-30 and EN 50160. The adopted methodological approach combines topological analysis, dynamic electrotechnical modeling, and empirical data utilization, thereby offering a robust operational framework for optimal PV sizing and siting in weakly interconnected African networks. The study also highlights that these benefits are achieved without the need for costly compensation equipment such as STATCOMs or SVCs, reinforcing the economic feasibility of this solution for developing countries. Beyond its environmental merits, photovoltaic energy emerges in this context as a strategic tool for modernizing MT networks, contributing to enhanced voltage stability, improved power quality, and greater overall system resilience. This research thus provides actionable recommendations for energy planning and intelligent renewable integration strategies in African settings.