Investigation Of Distributed Generation In Improving Power System Reliability

Abstract

This thesis work is the study of Distribution Generation (DG) in improving power system reliability, of Adama distribution substation. The first task of the study was to analyses the main failure factors and to evaluate the reliability of the existing distribution system by collecting and analyzing data from Adama substations and calculating the most powerful reliability indices, then to improve the reliability of the system by using DGs. The present Adama substation has encountered frequent power interruptions and power quality problems. 50% of the total interruption duration, and 44% of the total interruption frequency is mainly caused by planned (operational) problems, and 36% of the total duration and 32% of the total frequency of interruption is due to permanent short circuit. The substations system average interruptions frequency index (SAIFI) and system average interruption duration index (SAIDI) are 156.23 and 148.248 respectively. This reliability indices are then far from the EEPCO’s standard which set (SAIFI= 20 and SAIDI= 25) and the standard of other countries. To alleviate this problem, integrating distributed generation to the existed system is analyzed in this thesis. Distributed generation is a generation of an electric power close to the load. The resources are wind generators and Photovoltaic PV solar arrays, fuel cells and so on. Since Adama is rich in wind and solar energies, such renewable energies should be explored for system reliability improvement. The study utilized different meteorological and statistical data and like MS-Excel, Digsilent powerfactory software. The simulation is used to evaluate the power distribution substation to ascertain that, it produces the desired reliability improvements. The result of the simulation shows that the integration of DGs can advance the reliability indices values. Assuming that all DGs and protective devices are fully reliable and DGs are engaged at all feeder lines the overall reliability of the system can be improved up to the standard set by EEPCO and even more. “This means that the average service availability index (ASAI) become 1”. And the others zero. But locating DGs to all feeders requires high investment cost.