A Four-State Model For Estimate of Outage Risk for Units in Peaking Service

The conditional probability of a unit not being available given a demand occasion is developed using a four-state Markov model. The authoring Task Group recommends that the developed conditional probability be used in place of Forced Outage Rate for capacity planning studies, especially when the application is for units in peaking or cycling service. The Forced Outage Rate parameter has been recognized to be unsuitable as a measure of outage risk when unit annual service hours are low. This paper describes other models which have been used or offered in addressing the problem. After reviewing available models and known associated work, the Task Group developed the recommended four-state model.