Transformer Outage Contingency in the Southern Interconnected Grid of Cameroon Based on Dynamic Power Flow Simulation

Abstract

Te power system is a network of components having specifc operational limits such that any violation of these limits during their operation could lead to more damage in the grid. Te grid in Cameroon has been facing several undesired loading events at some sections of the network and the utility company has over the years, employed measures to mitigate these issues. Tis study has used the ETAP software to conduct a contingency analysis on the largest independent grid in Cameroon, supplying 6 regions in Cameroon. Seventeen transformer outage events in the network were used to conduct the N-1 scenario-based contingency, so that the vulnerability of the network can be evaluated. Te fast decoupled power fow method was continuously applied on the network, and the diferent contingency scenarios were ranked using a combination of 4 performance indices. Tese four performance indices gave information on the impact of the various transformer outage scenarios on the grid. Te four indices were added to give a combined value, and the outages were ranked in order of severity based on this combined index. A major contribution of this paper is the use of four scalar indices to classify the critical elements in the grid of a developing country. Te initial load fow simulation of the network showed that 12 nodes had under voltages, while 3 transformers and one transmission line were overloaded. Te Ngousso corridor sufered one of the worst under voltage situation during the initial power fow study. Tis is an indication that the utility company needs to undertake intensive network upgrade and implore measures to increase power generation to support the growing loads. It was observed that all the contingency scenarios experienced convergence. Te Oyomabang transformer 1 had the highest combined index of 71.20, showing a huge negative impact on the network as a result of the outage of the transformer. Tis was followed by the Oyomabang transformer 2 with a combined index of 48.63. Te results will be very useful to utility operators in prioritizing transformers in the network with high risk of causing huge impact on the network in case of an outage.