Distribution system reliability assessment - From measurement of performance to prediction of future

The electrical utilities are facing market conditions and therefore have to plan and operate their distribution systems in a cost effective way. This implies that the customers requirement on reliability i.e. availability, has to be balanced towards the cost for obtaining the same. An effective way of solving this issue is by the use of quantitative assessment of reliability, i.e. reliability indices, which is based on probability theory. However, these methods require input data that defines the condition for the system and its components. The aim is to predict the future behavior based on collected data and measured performance. Reliability centered maintenance (RCM) is a systematic approach for handling this complexity of relating the benefit in reliability by different preventive actions in obtaining the same i.e. preventive maintenance with aim of lower the frequence of supply interruptions. This presentation focus on: firstly, how to measure performance and identify system past and secondly, how this information can be used for predicting the future condition. Furthermore, this is made by showing on results from an RCM application study of a cable distribution system where real system and component reliability input data has been used for prediction of system reliability.