Electric power distribution system reliability is defined as the ability to
deliver uninterrupted service to customers. Deregulation of the electric p
ower industry has forced utilities to face new challenges and to evaluate t
he cost-benefit implications of providing an acceptable level of service. T
his paper presents a fuzzy knowledge-based approach for reliability plannin
g purposes. This approach makes a direct assessment of the circuit configur
ation and hazards and assigns each section and feeder a relative risk index
by expressing the configuration variables mathematically using fuzzy logic
. Results obtained using the fuzzy model on actual utility feeder data are
presented and the correlation between the fuzzy model results and actual fe
eder performance is obtained. Determination of the highest risk feeders and
of the feeders which benefit the most from a given reliability improvement
project are the major goals of the paper.