An Evaluation of System Record-Based Causes of System Collapse Incidences of Nigeria’s Transmission Grid

This paper presents an assessment of system collapse causes in Nigeria’s 132-330kV Grid. Long-term monthly data of system collapse incidences (SCI) from grid’s record was analyzed using statistical analytical procedures and adapted equations. Results established that the most probable cause of SCI is transmission grid faults at 81.6%, followed by generation faults at 13.2%, and lastly, intermediate faults at 5.2%. Furthermore, probability of non-occurrence of system collapse in a month is approximately 31%, which is low and an indication of fragile grid, requiring rigorous daily system planning, monitoring and control. Furthermore, the probability of at least 1 occurrence of SCI is also 31%, which is high and an indication that the grid is not safe from possible contingency that can result in total loss of the grid. Load loss impact of SCI is rated at an annual average of 20% for partial system collapse (PSC), while load loss would be 100% for total system collapse (TSC), implying huge costs on the national grid. These analyses indicate that the transmission network of Nigeria is most susceptible to faults that leads to SCI and needs to be investigated for specific vulnerabilities that can cause system instability and failure.