Development of an algorithm for switching distribution feeders to avoid frequent under frequency trips in a power system

Abstract

Though load shedding is not expected in modern days, depending upon the situation it may become unavoidable to prevent the power system from facing total blackout or to combat the under frequency problem in contingency situation or sustained generation deficit in the system. A good load shedding procedure may decrease the inconvenience when generation is remarkably less than demand. In this work an algorithm has been developed to decide in advance or just prior to the required period a schedule for manual load shedding for 11 kV feeders so that occurrence of under frequency in thy system is reduced. In this algorithm emergency power requirement of customers under different feeders, the individual feeder priority and previous status have been considered. It has also been considered that a feeder will not be shed for two consecutive time slots. The algorithm finds the best combination from a set of candidate combinations (equal to the number of slots) based on several key indices. The outcome of this study will help the distribution agencies prepare an easy-toimplement load shedding schedule especially if the number of 11 kV feeders in a 33/11 kV substation is too large to be switched on/off optimally applying only thumb rules.