Power-to-hydrogen: Physical modeling and dynamic control

This article analyses a power-to-hydrogen system designed to convert intermittent renewable electricity into compressed hydrogen. The proposed configuration combines a floating photovoltaic and offshore wind hybrid supply with an alkaline electrolyser, a buffer tank, a compression unit, and a high-pressure gaseous hydrogen storage. The choice of this hybrid supply is motivated by the need for renewable energy solutions with limited land use to achieve carbon neutrality. The combination of floating photovoltaic and wind power sources reduces the duration of electrolyser shutdowns by compensating the inherent fluctuations of each source. However, the intermittency still persists, so this study focuses on developing detailed physical models in Python to capture the behaviour of the power-to-hydrogen chain under intermittent conditions, together with appropriate control strategies that maintain stable operation. The offshore wind and floating photovoltaic models are used to simulate the electrical power generated and supplied to the electrolyser for hydrogen production. The PID-based thermal regulation of the electrolyser is formulated as a nonlinear programming problem in which the gains are obtained through dynamic optimization subject to the stack physical model. A pressure-regulated compression strategy is also proposed, in which the discharge pressure follows the storage-tank pressure, reducing the cumulative electrical demand of the compression unit relative to a fixed-pressure compression. The proposed process is generalisable to any intermittent renewable supply and provides a basis for the dynamic analysis and control design of power-to-hydrogen systems.