Real-Time coordination of electrical and thermal energy in power-to-hydrogen by electrolysis plant

Abstract

This paper proposes a real-time coordination strategy for an industrial power-to-hydrogen by electrolysis (PtHE) plant under fluctuating renewable energy sources (RES). In this plant, an optimal coupling between electrical and thermal energy can improve the performance of the water electrolysis reaction. To maximize hydrogen production under power fluctuations, an optimization model considering the electrical-thermal coupling is first established, where the piecewise linear approximation is applied to transform nonlinear relationships in the PtHE plant into constraints in the form of mixed integer linear programming (MILP). Then, a real-time operation strategy of the PtHE plant is proposed to coordinate electrical and thermal energy for efficient conversion, where model predictive control (MPC) is adapted to determine the allocation of fluctuating power in real-time by solving the MILP optimization problem. Besides, a power hardware-in-loop (PHIL) platform is built to implement the proposed strategy, which includes an industrial alkaline PtHE plant and a real-time simulator. Through the experiment, the control execution of this platform is validated, and the parameters of the alkaline PtHE model are obtained. This strategy is applied to the PtHE plant in the PHIL platform and compared with the myopic policy to demonstrate the advantage: the total hydrogen production increases by 9% with no power curtailment of RES by the temperature management in advance using MPC. Further, a simulation on a high-capacity PtHE plant, up to MW scale, shows a 5% improvement in the total hydrogen production under the proposed strategy, compared with a commercial solution using programmable logic control (PLC). Results confirm that exploiting the electrical-thermal flexibility significantly enhances the energy conversion under varying conditions brought by RES, offering a practical route to promote green hydrogen production in industrial applications.