Multi-objective optimal operation of coastal hydro-electrical energy system with seawater reverse osmosis desalination based on constrained NSGA-III

To make best use of available coastal renewable energy and to meet local freshwater demand, optimal operation of a coastal hydro-electrical energy system with consideration of seawater desalination is proposed in this paper. The paper outlines a system configuration which is used to develop the virtual energy storage characteristics of a desalination plant and in which cost-savings are demonstrated while preserving the local desalinated water supply. To achieve the control criteria, minimization of the total period cost and tie-line power fluctuations are considered as two objectives in an objective function. Constraints are established based on the system configuration and the multi-objective optimization problem is solved with the third generation of the constrained non-dominated sorting genetic algorithm (NSGA-III) algorithm. Virtual energy storage characteristics of the desalination units is studied and utilized in the model. The paper examines several case studies to verify the feasibility and merits of the proposed method. The operational characteristics of the virtual energy storage components in the system is discussed, and sensitivity analysis of the operating parameters of the pumped storage hydropower unit and the seawater desalination unit are also conducted. Simulation results show that the proposed optimal operation approach is suitable for calculating the total cost as well as assessing the power stability on the tie-line, and NSGA-III is capable of determining the Pareto-optimal operational plans of the system.