Scenario of power distribution network in the City of Dhaka in the context of reliability

In the modern world, the importance of uninterrupted supply of electricity cannot be overemphasized. Per capita consumption of electricity is universally adopted as a yardstick of the living standard of a nation. Three principal components in a typical electrical power supply system are (a) the generating plant (b) the transmission system and (c) the distribution network. All of these components must function properly to ensure the quality of electricity supplied. The present paper is concerned with the performance characteristics of the distribution network in the context of reliability. The distribution network plays a vital role in the total power system. This links the consumers and sells electricity produced by the generating plants. A number of factors influence the smooth functioning of the network system. Network structure, method of operation, fluctuation of voltage and frequency, nature of protection system, maintenance management, organizational structure etc. can be identified as the major factors. In this paper attempt has been made to investigate the reliability of electricity supply of distribution network under Kawran Bazar substation in particular and Dhaka city in general. Appropriate reliability indices have been calculated using the data and information collected from the concerned persons and departments. The distribution network under study having about 17 (seventeen) vulnerable elements is effectively a series system without any parallel facility. Failure of one or more of the elements in the system results in disruption of electricity supply of the selected part. Data and information gathered from relevant sources for the year 2001 have been utilized to evaluate the expected failure rate of the elements. These results have been used to determine the overall reliability of the system. The average outage duration has been estimated to be about 38 hours in the year. This parameter for a developed country like France is only 0.82 hours. Failure rates for individual elements of the system have been evaluated and the rates for switchgear overhead line, underground cable, transformer are unusually compared to any developed nation. Though this study is confined within a part of Dhaka, the scenario can be treated as representative for the whole of the city.