Penalty Factor Calculations Incorporating Interchange Constraints

The use of penalty factors to account for the effect of transmission losses in the equal incremental cost criterion for economic dispatch of generating units has been firmly established and applied to the real-time dispatch and control. For real-time applications, the methodology has been to generate several sets of _?-coefficients off-line and select one that approximates the network configuration and the system load level. More recently Jacobianbased algorithms have been proposed and several implementations are reported. Such algorithms have been proven feasible for on-line applications and produce results close to the real-time state of the system. However, most of the existing formulations are based on the overall system behavior and its performance. Whereas, in actual power utility operation interconnected with neighboring companies, the predominant objective is to minimize operational cost while maintaining the net interchange schedule. A Jacobian-based method is presented in this paper for use in such multi-area dispatch problems. The algorithm determines the generator penalty factors for the internal units such that the produced lambda is the incremental cost of delivering powerto the load center of the internal area while maintaining a fixed net interchange power. This is in contrast to the Lambda obtained from the single area technique which represents the incremental cost incurred to deliver power to the system load center. In addition, formulation for the penalty factor at the net interchange boundary of the internal area is developed. This is useful for the evaluation of the interchange transactions with the neighboring utilities.