Power system computer controlled load shedding

System conditions leading to power deficits and their identification are analyzed and the methods for load-shedding calculations are presented. Different criteria on which to base the decision-making process are discussed with the aim of defining an overall load-shedding protection scheme, based on real-time system conditions as processed by computer control centers. The basic theory to develop a new concept of load shedding is presented. Load-shedding schemes oriented to minimize the frequency transient fall compatible with limited amounts of disconnected load are sought. Real-time measurements of loads are used in a process to select, for each block of power, those feeders to be disconnected in an eventual emergency. The concept of area transient error (ATE) is introduced in order to look at the possibilities of using it as an indicator of system condition. A first load-shedding scheme applied in one area is based on the ATE. A second scheme, used as a backup, is applied throughout the system and is based on the frequency decay rate and a third crierion based only on power is presented. Tests on a sample system show the effectiveness of the proposed control strategy.