Evaluation and Improvement of Reliability Indices of Electrical Power Distribution System

Reliability of a power distribution system is defined as the ability to deliver uninterrupted service to customer. Distribution system reliability indices can be presented in many ways to reflect the reliability of individual customers, feeders and system oriented indices related to substation. Two approaches to reliability evaluation of distribution systems are normally used; namely, historical assessment and predictive assessment. The distribution system is an important part of the total electrical supply system. This is due to the fact that the distribution system provides the final link between a utility's transmission system and its customers. It has been reported that more than eighty per cent of all customer interruptions occur due to failures in the distribution system. Distribution System Strengthening and Distribution Automation (DA) system are being increasingly implemented under Restructured Accelerated Power Development and Reforms Programme (R-APDRP)/Integrated Power Development Scheme (IPDS) by the electric utilities to reduce the operational problems of distribution networks. System strengthening and the Distribution Automation (DA) system not only provides system wide status and health monitoring but also helps in coordinated controls required to enhance quality and reliability of the supply. In India, the Utilities calculate Reliability Index and the same thing submitted to Regulatory commission and Central Electricity Authority. The data base is not available to calculate all the Reliability indices as per IEEE 1366-2012. An attempt has been made in this paper to calculate Reliability indices which includes, System Average Interruption Frequency Index (SAIFI), System Average Interruption Duration Index (SAIDI), Customer Average Interruption Frequency Index (CAIFI), Customer Average Interruption Duration Index (CAIDI), Energy Not Supplied (ENS), Average Energy Not Supplied (AENS), etc.