Inclusion of cold load pickup events in reliability calculation for residential power distribution systems

Residential power distribution systems are subjected to cold load pickup failures after extended outages due to the presence of high number of thermostatically-controlled loads. This event can cause protection devices activation and consequently a restoration failure. Also, this event can cause electrical equipment such as transformer to be overloaded. The cold load pickup is usually not included in the reliability evaluation of power systems. This paper presents a method to model the residential load points with high concentration of thermostatic loads. This model depends on the ambient temperature and stochastic customer lifestyle as Monte Carlo sampling method used to randomly obtained the operation status of every device in every hour. This model, along with the outage duration effect, was then used to calculate the load pickup occurrence rate in residential loads and the effect of such an event in the reliability calculation of power distribution system. A simple test radial system was used to compute the system and load reliability indices with and without consideration of the cold load pickup events. Sequential Monte Carlo simulation was used in this reliability analysis.