Sensitivity analysis of reliability indices with respect to equipment failure and repair rates

This paper describes a methodology for calculating the sensitivity of reliability indices such as loss of load probability (LOLP), expected power not supplied (EPNS) and loss of load frequency (LOLF) with respect to variations in equipment failure and repair rates. This information can be used to assess the cost/benefit of improving equipment reliability, either reducing downtime by hiring additional personnel for repairs or extending uptime through more sophisticated monitoring and maintenance techniques. The sensitivity indices can also be used to estimate the impact of parameter uncertainty on reliability indices. The methodology is easy to implement on existing reliability evaluation programs, either based on state enumeration or Monte Carlo simulation, and does not require additional computational effort. Case studies with the 24-bus IEEE RTS and the 1400-bus Brazilian Southeastern system are presented and discussed