Incorporating Generating Unit Maintenance Scheduling in Power System Reliability

Scheduling generating unit maintenance is an important and necessary function in both vertically integrated and deregulated power systems. The objective in scheduling preventive maintenance is to ensure that the resulting risk to the system does not exceed a predetermined acceptable level. In a deterministic approach, the acceptable margin is either, a percentage of the available capacity or load, or a value equal to the largest loaded unit. A hybrid approach designated as the health levelization technique that combines a probabilistic evaluation and an acceptable deterministic criterion into a single framework is described. The health levelization approach is used to schedule unit maintenance on both annual and short term bases. The development of the health levelization technique and its application in both short term and long term unit maintenance scheduling is presented. The effect on maintenance scheduling of different factors such as load profiles, load forecast uncertainty, and time dependent unit unavailability is examined. The concepts and procedures presented can be used to schedule maintenance in both vertically integrated and deregulated power systems.