Optimal Coordinated Control of a Renewable Water–Energy Microgrid Connected Seawater Pumped Storage and Desalination for Coastal Communities

Isolated microgrid, offshore platforms, and coastal communities face a dual critical challenge: ensuring a reliable electricity supply and continuous access to potable water while limiting dependence on fossil fuels. This paper deals with the design of a new water–energy microgrid architecture dedicated to a small island community and remote area, combining renewable power generation, hybrid energy storage, and seawater desalination. The investigated system integrates onshore photovoltaic (PV) panels, offshore wind turbines connected via a high-voltage direct current (HVDC) link, a seawater pumped storage plant using a single upper reservoir, a flywheel energy storage system (FESS) for fast power smoothing, a reverse osmosis (RO) desalination plant, a freshwater storage tank, and a small backup diesel generator.

In the first stage, a global coupled electricity–water model was developed. Then, an optimal control strategy using a recent metaheuristic algorithm was proposed to coordinate renewable generation, the pumping/turbining modes of the pumped storage plant, and the power allocated to the desalination unit. A small-signal stability analysis was also carried out around several representative operating points, examining dominant eigenvalues, damping margins, and the sensitivity to control and storage parameters (pumped storage, FESS).

Time-domain simulations and frequency-domain analysis show that the proposed architecture can maintain power–frequency balance in the microgrid while ensuring continuity of water supply. This work therefore lays the groundwork for a more advanced study of an Energy Management System (EMS) and multi-objective water–energy optimization, which will be addressed in future works.