Estimation of Cold-Load Pickup Occurrence Rate in Distribution Systems

Cold-load pickup as a result of a major contribution of thermostatically controlled loads in the distribution networks causes unpredictable outages in the system. Most of the studies carried out thus far have been devoted to find the nature of the cold-load pickup and have attempted to model its behavior in distribution systems. However, less effort has been made toward estimating the occurrence rate of the cold-load pickup in distribution systems. The occurrence of this phenomenon is a stochastic process, which depends on several factors. Hence, it seems necessary to develop a methodology which enables the estimation of the occurrence rate of the cold-load pickup in distribution systems. The purpose of this paper is to provide this methodology based on a model that estimates the cold-load pickup peak magnitude relating to the outage time. The operation of the protective devices is evaluated within the cold-load pickup situations, and the resulting outages are investigated in the network. The IEEE 34-bus system and a real test system are used as case studies to show the methodology results and to present the cold-load contribution in the network outages based on the simulation of the real measured load data.