Mitigating Voltage Drop Limitations in A Long-Distance Transmission Network: A Case Study of the Nigerian 48-Bus System

Voltage drop remains one of the major operational challenges affecting long-distance transmission networks, particularly in developing power systems where generating stations are located far from major load centers. Excessive voltage drop leads to poor voltage regulation, increased transmission losses, reduced power transfer capability, and weakened system stability. This study investigates the application of the Thyristor Controlled Series Capacitor (TCSC) for mitigating voltage drop limitations in the Nigerian 48-bus transmission network. The Nigerian 330 kV grid was modeled as a 48-bus interconnected power system comprising generating stations, transmission substations, and load centers. Load flow simulation was carried out under two operating scenarios: without compensation and with TCSC integration. Bus voltage profiles and voltage drop indices were compared to evaluate the effectiveness of the device. The results showed that, under the uncompensated condition, several buses experienced significant undervoltage, with the most critical bus voltage recorded at 0.90321 p.u. After the installation of the TCSC, weak buses recorded noticeable voltage improvement, and the minimum bus voltage increased to 0.93048 p.u. Major weak buses such as Jos, Markurdi, Ikot Ekpene, Ugwuaji, and New Haven showed substantial recovery toward acceptable operating limits. The average network voltage drop decreased from 0.00962 p.u. to 0.00550 p.u., representing a 42.83% reduction. The improvement was achieved through the ability of the TCSC to reduce effective transmission line reactance, thereby minimizing reactive voltage losses and enhancing power transfer across long-distance corridors. The study concludes that TCSC is an effective and technically viable FACTS solution for improving voltage regulation, strengthening voltage stability, and enhancing transmission efficiency in the Nigerian power grid. Its deployment can provide a cost-effective alternative to network expansion while improving reliable electricity delivery to distant load centers. Index Terms: Voltage Drop, TCSC, FACTS Devices, Nigerian 48-Bus System, Voltage Stability, Transmission Network, Load Flow Analysis.