Reliability evaluation of generating systems considering aging processes

•A new method that allows the effects of generator aging to be included in the reliability analysis of power systems is proposed.•A novel model for the failure rate capable of representing the stages of normal operation and wear-out is described.•Catastrophic failures and equipment refurbishing actions are also included in the proposed method.•The new method is built using a chronological Monte Carlo simulation and variance reduction techniques.•The aging of components can cause significant reductions in the reliability of generating systems. Equipment aging has been a major concern among electric utilities’ planners, since quality of service can be put at risk. This paper proposes a new method that allows the effects of the aging of generators to be properly included into the reliability analysis of power systems. First, a new model for the failure rate capable of representing the stages of normal operation and wear-out, replacing the adoption of constant failure rates, is described. The effects of repairable and non-repairable (i.e., catastrophic) failures on the reliability assessment of generation systems are also discussed. The proposed method is built from the previous models using a sequential Monte Carlo simulation and variance reduction techniques. To validate the proposed method, the IEEE Reliability Test System is used with modifications in which different ages are defined for existing generating units that are progressively aging over the years. Several tests are described together with strategies for adopting preventive refurbishments and the corresponding results are duly discussed.