An expert system approach of congestion management for security and economy oriented power system operation

Alleviation of the emergency transmission line overload is a critical problem in the present day power system operation; hence a control strategy is necessary to effectively reduce the line overloads to the security limits in shortest time, by generation rescheduling and/or load shedding, not giving priority to the economic considerations. In the literature, many methods have been reported for determining a secure operating point. Most of these methods use conventional optimization techniques, which are generally time-consuming from a computation point of view, especially for large systems. Further the conventional optimization technique updates all the controllers for most of the operating conditions. Under emergency conditions the operator, has to make quick decisions, with little concern for the theoretical optimality of the operating point and also the operator can not move all the controllers to different settings within less time. In this context a simplified expert system approach has been proposed in this paper for security and economy oriented power system operation. The proposed approach is used to remove the congestion in the transmission lines by generation rescheduling with minimal cost involved in the rescheduling process. An attempt has been made for curtailing the number of generators to be rescheduled based on the incremental fuel cost of generators and the Relative Electrical Distance (RED) concept. Under emergency operating conditions the proposed approach helps the operator in the load dispatch centre for improving the system security with the rescheduling of few number of generators for overload relieving with less incremental fuel cost. The proposed approach has been illustrated with an IEEE 39 bus New England System.