COLD LOAD PICKUP IN POWER DISTRIBUTION SYSTEM

Abstract

Thermostatically controlled electrical devices contribute a major portion of the entire power demand of a power distribution system. Restoration of these systems after prolonged outage produces higher load demand than the preoutage load. This condition is known as cold load pickup. The situation arises owing to loss of diversity. Due to loss of diversity of loads, the restoration of distribution feeders after long interruptions creates cold load pickup conditions. As a result, the total load briefly exceeds the substation transformer rated load. In order to prevent overheating of these transformers, the distribution system load may have to be restored in a step-by-step manner using sectionalizing switches. In this work we have taken a distribution system (Roorkee) from this network data we have calculated loading limits of the transformer as well as minimum restoration time of the network by using different algorithms (GA & ACO) and finally checking the convergence of these methods. The distribution system (Roorkee) data is analyzed with comparison of delayed exponential model given by author. The ambient temperature has been taken from National Institute of Hydrology for finding the transformer loss of life. The loss of life is checked with IEEE Std. C57.92.1981.