Solution to Unit Commitment Problem with Spinning Reserve and Ramp Rate Constraints Using Ant Colony System

In this paper unit commitment problem (UCP) with spinning reserve and ramp rate constraint has been solved using Ant Colony System (ACS). In this model, foraging behavior of the real ants for finding its food from its start (nest) to its destination (food) is simulated to obtain the optimum solution. A search strategy has been adopted which involves the artificial ants to obtain the minimum cost path for the commitment of thermal units for the given time period. The search space is seen as the multi stage decision, which provides the ant search a competitive edge over conventional Dynamic programming (DP) method. In the first step all possible combinations of the states satisfying the load demand with spinning reserve have been selected for ants search space. Then the artificial ants are allowed to explore the minimum cost path in that search space. The proposed ACS model has performed successfully for a ten-unit generation system and may be extended to practical systems with large number of units. ______________________________________________________________________________________