A unified index for power distribution reliability/power quality indices

There is much current interest in electric power distribution system reliability and power quality. Reliability is increasingly assessed using the indices SAIFI, SAIDI, and CAIDI. More recently, a similar index, MAIFI, has been proposed to assess the level of momentary interruptions on a distribution system. Power distribution companies are being asked to improve their performance by lowering these indices. The indices, however, can give conflicting results to system changes, and designers find it difficult to compare competing design options. This paper proposes a single index which combines the performance information captured by SAIFI, SAIDI, CAIDI, and MAIFI. This index incorporates customer preferences on interruption frequency and duration, and is readily adaptable to local conditions and preferences. The paper includes a detailed case study that demonstrates the performance of the proposed index relative to these existing reliability and power quality indices.