VOLTAGE PROFILE REGULATION AND TRANSMISSION LINE LOSS MINIMIZATION USING UNIFIED POWER FLOW CONTROLLER (CASE STUDY: SOUTHEASTERN REGION OF ETHIOPIA) MSc. THESIS

Abstract

Transmission systems are critical in the transmission of electricity from power plants to distribution stations. However, as the load demand and generation units grow without transmission network expansion, the transmission line is exposed to power losses. Moreover, the result of increased power losses over the transmission network decreases the bus voltage profile. Therefore, the thesis aims to reduce transmission line loss and increase the voltage profile of the southeastern region part of Ethiopia's transmission network by using the FACTS device. Hence, this thesis used the FACTS family called unified power flow controller (UPFC) which is the most versatile and flexible FACTS device that controls power in the transmission systems by controlling the impedance, voltage magnitude, and phase angle between two buses either simultaneously or selectively and it contains two voltage source converters. The first converter is connected in parallel to the transmission line through a shunt transformer and the second is connected in series with the transmission line through a series-connected transformer. The necessary data was collected from the Ethiopian Electric Power (EEP) and the data was analyzed under peak load to find a solution to the problem. The UPFC modeling and simulation and coding studies have been carried out using MATLAB R2017b software. Ant Colony Optimization (ACO) algorithm was used to get the optimal place and rating of UPFC. The result showed that UPFC was installed at bus 7 with a rating of 52.773 MVar. Depending on this rating, the incorporated UPFC to the southeastern region part of Ethiopia has an annual financial saving of 125.092 million ETB and it improves the voltage profile of buses in the acceptable limits of 0.95 and 1.05. Generally, the existing transmission network has total 183.72 MW real power demand and 79.38 MVar reactive power demand. Incorporating of UPFC to the network reduces total power loss from 28.1662 MW to 16.6705 MW and 16.6236 to 13.6012 MVar real and reactive power loss respectively.