IMPACTS OF GENERATING UNIT UNRELIABILITY ON POWER SYSTEM ADEQUACY AND COSTS

This research work investigates the impacts of generating unit unreliability on the system adequacy level, production costs, failure costs and capacity costs in an electric power system. Generating system adequacy is primarily governed by the generating unit forced outage rates. This research activity examines the impact of generating unit forced outage rates on the expected system energy not supplied. This parameter is utilised to create an interrupted energy assessment rate in order to study the failure costs due to system unreliability. A procedure known as segmentation which is based on the convolution of machine outages and system hourly loads in the form of adding statistical moments is used as the main tool to determine the system unsupplied energy, production costs, failure costs and subsequently to evaluate the worth of unreliability in two test systems. The generating unit forced outage rates also affect the system peak load carrying capability. This involves additional capacity costs to compensate for the reduced level of reliability. This thesis utilises present worth analysis to determine the average cost associated with a unit increase in the load carrying capability. Generating unit availability can be improved by unit and plant refurbishment. The worth of generating unit refurbishment is assessed in terms of system costs and capacity costs. The methodology for evaluating the worth of refurbishment in terms of production costs, failure costs and capacity costs is explicitly stated and tested using two test systems. The concepts involved in the inclusion of generating unit forced outage rates in generating capacity adequacy assessment, evaluation of system unsupplied energy, production costs, failure costs and capacity costs associated with increasing the load carrying capability are illustrated by numerical examples