Power system components suffer from aging

wearing and hidden failures in operation

thus the component failure rate is increasing over time. By considering the main outage types of generators

transformers and transmission lines

the corresponding increasing failure rate model is built. From the model

the average unavailability formula incorporating preventive maintenance is derived. Based on the reliability cost-benefit analysis and the average unavailability

the LOLP

EENS and the total cost of the system can be deduced as a function of the preventive maintenance cycles of components

respectively. A heuristic iterative algorithm is proposed

in which the sensitivity of the total system cost to each component preventive maintenance rate is ranked to find the optimal preventive maintenance. According to studies on RBTS and IEEE-RTS79

it is verified that the component optimal maintenance cycle varies with the type

capacity

reliability and the location of that component. Finally

the effects of the aging factor and unit power shortage cost on maintenance optimization are treated based on the RBTS system.