Contingency Analysis in the Southern Ethiopian Power Transmission Network using Particle Swarm Optimized Unified Power Flow Controller

Abstract

Frequent line contingencies are a major driver of voltage limit violations and transmission line overloads within the southern power network, which comprises 28 lines and 27 buses. This paper analyzes the effects of single-line contingencies and proposes using a Unified Power Flow Controller (UPFC) to mitigate voltage violations and line overloading. A MATLAB tool was used to simulate the network under single line outage scenarios, both before and after the integration of the UPFC. The optimal placement and parameter settings of the UPFC are determined using a performance index and the Particle Swarm Optimization (PSO) technique. The results indicate that the outages of lines 1, 20, 6, 17, and 19 are the most critical, in descending order. In particular, the outage of line 1 resulted in 23 overloaded lines and 21 buses operating beyond their voltage limits. However, by installing a 75 MVAr UPFC at line 6, the violations were significantly reduced to one overloaded line and no buses outside the normal voltage range. The results demonstrate that optimally placed UPFC significantly enhances voltage stability and transmission capacity under N-1 contingencies.

Keywords: MATLAB, Particle swarm optimization, Performance index, Single line contingency, Southern Ethiopia, Transmission line overloading, Unified power flow controller