Estimation of the overload-related outages in distribution networks considering the random nature of the electrical loads

The overload phenomenon in distribution networks is a prevalent event, which usually causes the unwanted outages happen in distribution networks. The malfunction of the protection system as a result of high load currents during the overload situations yields network outages which are often unpredictable. The reliability indices in distribution systems are currently calculated neglecting the effect of overload condition. Having a correct estimation of the number of the overload-related outages in distribution networks enables the network planners and operators to better choice a proper solutions to avoid or decrease the side-effects of this event. In this study, in order to estimate the outage rates in distribution networks because of the overload phenomenon, a stochastic model for the electrical loads is presented. The normal cumulative distribution function is used to model the magnitude of the load demand at any time of the day. Monte Carlo approach is applied for random selection of the load magnitude. Load model results are compared with real measured data and the validity of the results is investigated. Electrical loads of the IEEE 34-bus system are modified by incorporating the real load variation curves to provide more realistic results. The results are presented and analysed in detail.