Application of adverse and extreme adverse weather: modelling in transmission and distribution system reliability evaluation

The physical environment in which a transmission and distribution system resides has a significant impact on the resulting reliability of the network. The inclusion of weather conditions in the reliability analyses of transmission and distribution systems is discussed. A series of weather models is presented with application to a practical transmission/distribution system. The conventional approach to predictive reliability assessment using singleand two-state weather models is briefly illustrated. A three-state weather model is presented to incorporate failures occurring in major adverse weather conditions. The system reliability indices obtained using the weather models clearly show the need to incorporate weather effects into reliability analyses. Results obtained without weather considerations can be quite misleading and optimistic.