Project Evaluation and Selection at MidAmerican Energy

Summary form only given. Electric utilities are on a never ending quest to attain higher levels of performance for increasingly lower costs. An important part of this effort is to define meaningful definitions of performance. For distribution reliability typical approaches use reliability indices such as the system average interruption frequency index (SAIFI), the system average interruption duration index (SAIDI), and the customer average interruption duration index (CAIDI). From a project evaluation and selection perspective, a target (i.e., performance standards) should be set for each reliability index target, and projects should be selected to that all targets can be achieved for the lowest possible cost. Setting performance standards based on reliability indices is problematic since it is impossible to usefully compare indices from one utility to other utilities. There are too many differences between data collection processes and utility system characteristics to make the development of universally applicable standard metric values and comparisons against such standard metric values valid. At MidAmerican Energy, standards have been set based on a careful examination of the relevant factors that affect reliability indices. This assessment is coupled with survey information that identifies the customer cost associated with service interruptions. The result is a set of performance metrics and targets that are customized to the MidAmerican system according to specific system characteristics and specific customer expectations. These metrics can than be used to drive the project evaluation and selection process