Benchmarking of reliability indices for electricity distribution utilities: Approach and discussion

Reliability indices viz. System Average Interruption Duration Index (SAIDI), System Average Interruption Frequency Index (SAIFI), Average System Availability Index (ASAI) etc. are measures of system wide reliability provided by an electricity distribution utility. These indices also indirectly indicate the utility's Operations and Maintenance (O&M) efficiency, system's ability to transfer load to the neighbouring units in case of cable or equipment failures, response time to locate and isolate a fault and restoration time. A distribution utility would like to benchmark the indices and to investigate the cause of inferior indices, if any. Benchmarking of reliability indices is an important task to set the reference for a utility to improve upon it. A benchmarking model for reliability indices is presented using Data Envelopment Analysis (DEA). The model finds the best performing utility among the set of similar utilities based on the sets of inputs (Percentage of High Tension (HT) feeders, percentage of underground (UG) cables, load density and expected remaining life of transformers ) and outputs (SAIDI, SAIFI, ASAI). It has been observed that although benchmarking approach provides good inputs for improvement, further analysis is required to get a true rank of a utility in comparison to the best performing one. In the paper, a discussion on benchmarking of reliability indices is presented.