Open Access  Subscription Access

Consumers of electrical energy expect a network to support their apparatuses with continuous and reliable supply.This makes reliability studies an important task besides all the other analyses required for assessing the system performance. The paper presents an analytical approach in the reliability assessment of the Port Harcourt 33/11kV power distribution system. The assessment was performed with the 2009 power outage data collected from the monopolistic operator of the Nigerian power system, National Electric Power Authority (now unbundled and called Power Holding Company of Nigeria, (PHCN) Plc) on the four substations: Marine-Base, U.S.T., Old-GRA and PH-Town injection substations radiating from the Port Harcourt Town 132/33/11kV transmission/injection substation. Thus, this study will enable utilities to determine the state of reliability of each substation and hence, provide a standard for prioritizing maintenance and upgrade of its distribution substation facilities.