Optimal Placement and Sizing of SVC, TCSC, and UPFC in the Nigerian 330KV Grid Using Particle Swarm Optimization

The Nigerian 330 kV transmission network plays a critical role in bulk electric power delivery across the country, yet it continues to experience operational challenges such as weak voltage profiles, excessive transmission losses, congestion on key corridors, and limited loadability. These issues reduce the efficiency, reliability, and stability of the national grid. This study presents the optimal placement and sizing of Flexible Alternating Current Transmission System (FACTS) devices, namely the Static Var Compensator (SVC), Thyristor Controlled Series Capacitor (TCSC), and Unified Power Flow Controller (UPFC), in the Nigerian 330 kV 48-bus power system using Particle Swarm Optimization (PSO). The objective was to minimize voltage drop, reduce real power losses, and improve network performance through intelligent compensation planning. A base-case load flow analysis was carried out in MATLAB/PSAT to determine voltage magnitudes, line loading conditions, and weak buses in the network. Results identified Jos, Ugwuaji, and New Haven buses as the most voltage-deficient locations and were selected for SVC placement. The Ugwuaji–New Haven and Jos–Markurdi transmission lines were identified as suitable locations for TCSC installation, while UPFC devices were placed at the midpoint of the same lines. PSO was then applied to determine the optimal compensation size subject to network operating constraints. The optimization process converged successfully with a best objective function value of -5974.45942 and produced optimal decision variables of . The corresponding equivalent FACTS impedance obtained was 37.5546 Ω. Comparative analysis showed that PSO-based placement significantly outperformed random placement, reducing transmission losses from 182.4 MW in the uncompensated system to 121.5 MW under optimized compensation. Compensation sensitivity analysis further showed that increasing compensation level from 0% to 60% progressively reduced losses, with 60% compensation providing the best operating condition within the tested range. Among the devices studied, the UPFC produced the best overall technical performance due to its simultaneous control of voltage magnitude, transmission impedance, and active/reactive power flow. The study concludes that PSO is a reliable and computationally efficient tool for solving the nonlinear FACTS placement and sizing problem. Strategic deployment of optimally sized FACTS devices offers a practical and cost-effective approach for improving the performance of the Nigerian 330 kV grid and reducing the need for immediate transmission expansion.

Keywords: Nigerian 330 kV grid, FACTS devices, Particle Swarm Optimization, SVC, TCSC, UPFC, transmission loss reduction, voltage stability, power system optimization.