Optimal vegetation maintenance scheduling of overhead electric power distribution systems

Vegetation maintenance involves trimming or removing trees and brush near the overhead conductors to reduce the number of tree-related outages and maintain system reliability. This paper reports a maintenance-scheduling algorithm that determines the optimal location and time for performing vegetation maintenance on overhead distribution feeders. A vegetation failure rate model is developed that quantifies the impact of the maintenance schedule on the reliability of a distribution system. Using this reliability model and a predictive reliability assessment algorithm, the maintenance-scheduling algorithm is formulated as a combinatorial optimization problem that considers different objective functions and constraints. After experimentation with several heuristic search techniques, a hybrid genetic algorithm-hill climbing technique consistently found the highest-quality maintenance schedules. The results from applying the maintenance-scheduling algorithm to a real distribution system are also presented. It is shown that the new maintenance scheduling algorithm can find lower cost and more reliable schedules compared to standard fixed interval schedules.