An efficient decomposition approach for multi-area production costing

Abstract

This paper presents a new approach for multi-area production costing called SEG-GSIDES (segmented global simultaneous decomposition-simulation). It is based on the SIDES (simultaneous decomposition-simulation) approach which has been developed for computing reliability indices in a multi-area configuration. The global state space is obtained from the maximum number of units committed in each area and thus contains the state space corresponding to any set of committed units. In the GSIDES approach, the global state space is decomposed and the resulting sets are used to compute the required indices for any subset of units committed. The energy supplied by each unit is calculated by the difference between the expected unserved energy before and after unit commitment. In some cases it may be possible to obtain indices by decomposition alone but generally a decomposition phase is followed by a simulation phase. When the units committed are close to base loaded units, their contribution to unserved energy from the decomposition phase is low. The major contribution in this case comes from the simulation phase and this introduces an approximation due to convergence. To reduce this approximation the decomposition is performedsequentially on different segments of the global state space. In this way, the major part of the indices is obtained from the decomposition phase and this leads to a more accurate determination of energy supplied by the units. The concepts are illustrated using a small example system. Case studies are presented for the three area and four area IEEE-RTS systems.