A probabilistic approach to distribution system reliability assessment

The Pacific Gas and Electric Company (PGE), together with California Polytechnic State University in San Luis Obispo, has developed a personal computer program for evaluating the reliability levels of their electric distribution circuits. The program, called the Distribution Reliability Assessment Model (DREAM), incorporates historical outage information with circuit component failure rates and estimates of fault response and component repair times to compute expected levels of customer outage frequency and duration. The authors highlight recent enhancements to DREAM which allow for the evaluation of both overhead and underground circuits. The authors also describe their efforts to measure the accuracy of the DREAM calculations and the application of the program in predicting the reliabilities of 180 feeders