Comparative Performance Evaluation of FACTs for Transmission Congestion Mitigation in the Nigerian 330 kV Network

Increasing electricity demand and inadequate transmission capacity have intensified congestion and voltage stability challenges in Nigeria’s 330 kV transmission network. This study investigates the effectiveness of Flexible AC Transmission Systems (FACTS), specifically the Static Var Compensator (SVC) and Thyristor-Controlled Series Capacitor (TCSC), in mitigating transmission congestion, improving voltage regulation, and reducing power losses. A representative Nigerian 330 kV transmission network was modelled and analysed using NEPLAN 555. Base-case power-flow analysis was conducted to identify overloaded transmission corridors. The performance of the compensation schemes was evaluated by comparing transmission line loading and active and reactive power losses before and after integration. The base-case analysis recorded total active and reactive power losses of 388.33 MW and 980.82 Mvar, respectively. Following SVC integration, these losses decreased to 244.30 MW and 416.19 Mvar, representing reductions of 37.09% and 57.57%, respectively. TCSC integration achieved greater reductions, lowering active power losses to 109.976 MW and reactive power losses to 252.234 Mvar, corresponding to improvements of 71.68% and 74.28%, respectively. The results demonstrate that both FACTS devices can enhance transmission network performance, with TCSC exhibiting superior performance in reducing system losses under the investigated operating conditions. The findings provide a basis for improving congestion management and operational efficiency in Nigeria’s 330 kV transmission network.