Transient Stability Analysis of the Benin Sub-Regional 330 KV Power Network Under Three-Phase Fault Conditions Using Time-Domain Simulation

Abstract

The reliability of Nigeria’s 330 kV transmission grid, which serves as the backbone of national power delivery, is increasingly challenged by frequent faults and disturbances. This study presents a detailed transient stability analysis of the Benin sub-regional 330 kV network under severe three-phase fault conditions, employing the time-domain simulation method. A comprehensive model comprising 28 buses, 7 generating stations, and 10 major load centers was developed using MATLAB/PSAT. A balanced three-phase fault was applied at the Benin Transmission Station (TS) bus to determine the Critical Clearing Time (CCT) and observe system dynamic responses in terms of rotor angle, speed deviation, electrical power, and bus voltage variations. The results show that the system remains stable when the fault is cleared at or before 0.83 s, with the critical rotor angle reaching 1.3877 rad (79.52°). Beyond this time, the generators lose synchronism, leading to system instability. The analysis demonstrates the importance of swift protection coordination and fast-acting circuit breakers to maintain synchronism in the Nigerian high-voltage transmission grid. The findings provide essential data for refining relay settings and designing robust control mechanisms to enhance grid resilience.