Power Distribution System Reliability Evaluation Using Both Analytical Reliability Network Equivalent Technique and Time-sequential Simulation Approach

A power system is usually divided into the subsystems of generation, transmission, and distribution facilities according to their functions. The distribution system is the most important part of a power system, which consists of many step-down transformers, distribution feeders, and customers. Therefore to evaluate the reliability of power distribution systems is a very complicated and tedious process. This chapter illustrates a reliability network equivalent technique for complex radial distribution system reliability evaluation. This method avoids the required procedure of finding the failure modes and their effect on the individual load points and results in a significant reduction in computer solution time. A time-sequential simulation technique is also introduced in this chapter. In the simulation technique, the direct search technique is used and overlapping time is considered. The simulation technique evaluates the reliability indices by a series of trials and therefore the procedure is more complicated and requires longer computer time. The simulation approach can provide both the average values and probability distributions of the load point and system indices. It may be practical therefore to use the analytical technique for basic system evaluation and to use the simulation technique when additional information is required.