Hedging approach in Multi-Objective Simulation-Optimization of operation of Ilam Dam Reservoir using MOPSO algorithm

In this research, the simulation and optimization models are integrated to apply the reservoir hedging policy. The simulation of the studied basin is executed using the WEAP model to conduct the system optimization and the multi-objective MOPSO model is utilized so that the first purpose is to maximize the percentage of supplying demands, while the second one is to minimize the violation of allowable capacities of the reservoir during the operation period. In this regard, the operation modeling from the reservoir was carried out based on the current condition for a 360-month period. Finally, by defining the optimized scenario and applying the reservoir hedging policy, the optimization of the operation from the reservoir is conducted and the results were compared with the outcomes of the reference scenario. In this study, by considering 24 decision variables including 12 hedging level variables and 12 hedging coefficient variables, the optimal answers were achieved after 1000 iterations. The results showed that the violation of the allowable capacities has not occurred in any periods, while in the reference scenario the reservoir level has reached the dead level in sequent months with more water shortage which might lead to the lack of water supply in such months and serious damages to the system. Due to the application of hedging policy in the optimized scenario, the percentage of supply in the critical months has increased between 20-35% compared to the reference scenario, which indicates a significant reduction in the failure rate in such months compared to the reference scenario.