Sequential quadratic programming and analytic hierarchy process for nonlinear multiobjective optimization of a hydropower network

In this paper, an optimal annual scheduling for power generation (i.e. rule curves and volume of water releases) in serial or parallel hydropower plants is developed. Multiobjective programming and weighted sum method are used to convert a multiobjective problem to a single objective one. Furthermore, to obtain viable alternatives under existing uncertainty, some random weight vectors in the whole weighting space are generated and for each weight vector an optimal solution is found using sequential quadratic programming (SQP). Then, analytic hierarchy process (AHP) is used to select the best solution according to a given criterion, and determine the most preferred one. Besides, this method does not require choosing a priori preference for the objective function, thus making an ideal tool for handling complicated multiobjective models and easy to use with the aid of computer programs. Combination of multiobjective optimization and multicriteria decision analysis (MCDA) is an integrated methodology that is capable of dealing with complex water management problems. Various scenarios for dry, median, and wet years are assumed based on stochastic flows from external sources (e.g. flooding rivers, unexpected rains, etc.) coming into each reservoir, and turbine power generation is obtained from hill diagrams provided by the manufacturer. The application of this methodology is illustrated in a case study for optimal scheduling of Karoon River Basin, where the decision support system and optimization routines are implemented in MATLAB. The total energy productions for 10 optimized solutions under dry, median, and wet scenarios (generated from forty‐year historical inflow records) are calculated, and specific water consumption for each reservoir is obtained in different months. This can significantly help decision makers to have an optimal and more intelligent management over energy productions in hydropower plants and associated thermal power plants.