Component ranking and importance indices in the distribution system

Monitoring the condition of components helps taking preventive actions to avoid failures, and increases reliability. However, performing such monitoring for all components of the distribution grid is prohibitively expensive. Instead, distribution system operators could focus efforts only on the most critical components. In particular, importance indices enable to prioritise components according to a chosen criterion, and to adapt monitoring strategies. This study presents methods to rank grid components using outage data. The importance indices are based on: 1) de-energisation time; 2) frequency of failures; 3) disconnected power; 4) energy not supplied and 5) customer outage time. The results depend largely on the time period of the outage data considered for analysis. Some components’ rank varies with the chosen criterion. This indicates that they are critical with respect to a specific criterion. Other components are ranked high with all the methods, which means that they are critical, and need focused monitoring.