Contingency Analysis of Pre- and Post-Privatization of Nigerian Electric Power System Security

Abstract

This study evaluates the steady-state contingency performance of the Nigerian 330 kV transmission network before and after the 2013 privatization by reconstructing selected system topologies between 2003 and 2023 and analysing them using Power System Simulator for Engineering (PSSE). During this period, the grid expanded from 24 buses, 37 lines, and 7 generating stations to 52 buses, 84 lines, and 31 stations. Load flow and N-1 contingency simulations were conducted, with contingencies ranked based on thermal overloads, voltage violations, and convergence behaviour. Results show marked improvements in system security, with power-flow violations decreasing from 126 to 21, voltage-limit breaches from 351 to 4, and total violations from 522 to 31, indicating enhanced stability and efficiency in the post-privatization era. Despite these gains, the number of non-convergent cases rose from 4 to 12, reflecting operational challenges associated with network growth. Persistent convergence problems in the Shiroro–Kaduna corridor and new vulnerabilities in the Makurdi–Jos and Jos–Kaduna corridors were identified, while voltage issues in the North-East were linked to the Gombe–Damaturu–Molai lines. A strengthened grid configuration with additional corridors and reactive support is proposed to mitigate the remaining weaknesses and improve overall system robustness.