Inter-area power exchange preserving multi-area economic dispatch

This paper proposes a two-tiered approach to solving multi-area security constrained economic dispatch (SCED) in large interconnected power systems while preserving inter-area power exchange schedules. The multi-area SCED problem is decomposed into a higher-level master problem and regional sub-problems. The master problem optimizes equivalent power injection at tie-line buses in each area, in order to preserve the scheduled power flow of inter-area interfaces. In the subproblems, a regional SCED with all the detailed parameters of internal generators/loads will be performed with fixed tie-line power flow. Ward equivalencing-based network reduction is employed to perform power flow computation at the higherlevel dispatch. A novel virtual supply function is introduced based on the locational marginal price (LMP) for each tie-line bus. This virtual supply function internalizes the detailed supply and demand information within each area, and provides key information for faster convergence to global optimality. The proposed approach is shown to have good trade-off between global economic optimality and power exchange controllability. Furthermore, this approach allows fully autonomous dispatch of internal resources within each area. Experimental results of 3-area IEEE RTS are presented to verify the economic optimality and computational speed of this method.