Optimization Model for Design-Operation of Pumped-Storage and Hydropower Systems

Due to the importance of pumped-storage systems as a cost-effective energy producer and the high cost of those projects, this paper addresses the simultaneous design-operation optimization in the design phase of pumping systems in reservoir power plants. The optimization model maximizes the net benefit of installations in reservoir systems and is employed to design Khersan 1 and 2 power plants in the Khuzestan province of Iran. An optimization model is developed to determine design decision variables, including volume of reservoir, installed capacity of power plants, diameter of water transmission installations, and also operation decision variables including output volume of the reservoir at each time step and number of hours the power plant works in a day. To estimate the potential of pumped-storage power plants, two models of design are considered in (1) hydropower form and (2) pumped-storage form. The optimal design and operation of each of the aforementioned modes is accomplished by employing the nonlinear programming (NLP) code contained in the (language for interactive general optimization) LINGO 11.0 software package. Results of pumped-storage systems design and operation are compared to individual hydropower systems in the same area to determine the economic advantage of pumped-storage systems. Four criteria are considered to compare those two systems: (1) net benefit; (2) ratio of benefit to cost; (3) system efficiency criteria; and (4) mean, firm, and secondary-generated energy. Results indicate that pumped-storage systems have better outcomes than individual hydropower systems, based on the aforementioned four criteria.