Incorporating aging failures in power system reliability evaluation

The paper presents a method to incorporate aging failures in power system reliability evaluation. It includes development of a calculation approach with two possible probability distribution models for unavailability of aging failures and implementation in reliability evaluation. The defined unavailability of aging failures has a consistent form which is the same as that for repairable failures. This allows aging failures to be easily included in existing reliability evaluation techniques and tools. Differences between the two models using normal and Weibull distributions have been discussed. The BC Hydro North Metro system was used as an example to demonstrate an application of the proposed method and models. The results indicate that aging failures have significant impacts on system reliability, particularly for an "aged" system. Ignoring aging failures in reliability evaluation of an aged power system will result in an overly underestimation of system risk and most likely a misleading conclusion in system planning.