RELIABILITY ASSESSMENT OF ELECTRIC POWER DISTRIBUTION SYSTEM BY USING THE PROBABILISTIC APPROACH

摘要

Power supply discontinuity indicator (PSDI) is estimated in this paper under the fact that, the permanent growth of power demand of distribution system creates a convenient increasing of substations number and lines length, otherwise, the increasing of these variables changes the networks configuration. The problem is investigated here to determine the mathematical model which describe the relationship between the PSDI and the independent variables (lines and substations) or q= f(L,N ) in the (66) kV networks which play more important role in power distribution systems. The regression analysis is used for obtaining the (66) kV network mathematical model, taking into account that, this network is designed to be as a ring network at the end of the development plane similar to the southern region (66) kV network configuration in Syrian Arab Republic, where, the final configuration is achieved through a few stages of the interconnection development in two periods of time: (1985-1989) and (1990-1994), respectively. The method of estimating the reliability indices is developed on the basis of the minimal cutset and simulation techniques. The mathmatical model is done depending on the factorial experimental design after replicating the calculation of the following indices for every scheme of the network development: the expected failure rate, average interruption duration, average load disconnected, and average energy not supplied due to fault and maintenance interruptions. Confiding the goodness of fit of the mathematical model q=f(L,N) shows that: adjusting the Syrian (66) kV network configuration by increasing the lines length improves the reliability of supply (i.e. decreases the (PSDI)) more than the case of increasing the number of substations, until the moment that, the (66) kV network will be operated as a ring system. This fact ephasis the existed configuration, where, a few of substations is supplied yet radially.