Voltage stability improvement by construction of parallel transmission lines - Case study – Western Kenya Region.

Abstract

An integrated power system in any given economy is anticipated to provide steady and reliable power sufficient for peak loads. Several challenges have been witnessed in diverse power grids, despite research having been widely done to augment stability and enhancement. Transmission line infrastructures or lack thereof contribute largely towards these challenges. Majority of past works have focused on inclusion of Flexible Alternating Current Transmission Systems (FACTS) devices as a means of improving voltage stability and reliability. Western Kenya Region (WKR) among other locations globally have previously experienced voltage instabilities, whereby some led to voltage collapse. This research involved studying the status of transmission lines in West Kenya region and analysis of construction of parallel transmission lines along the main transmission path into Western Kenya Region to improve regional voltage profile. Surge Impedance Loading calculations and Benefit/Cost analysis were also done to predict the maximum loading of the transmission lines and investigate the economic benefit with respect to capital cost of the project respectively. The existing transmission system of Western Kenya Region and the parallel transmission lines were modelled on an IEEE 39 Bus System and simulated using the DigSilent Powerfactory software. The results revealed that simulation of parallel transmission lines improved the bus voltages and reduced the loading of the transmission lines, therefore improving to the possibility of increasing loads into the network, which was simulated at maximum demand. Parallel transmission lines improved the region’s voltage profile, where the lowest bus voltage of all the scenarios improved from 0.887pu to 0.942pu translating to an improvement of 6.2%. Power transfer capability also improved by 45.27%. The excess energy available for generation would also be put to its desired use. When loads in the future increase beyond magnitudes that present a voltage drop excessive of the threshold by over 6%, installation of capacitor banks with a minimum of 130MVAr or a suitable FACTS device would be appropriate at the bus having the weakest voltage levels, since loading of the transmission line had been significantly reduced.