Fractional-Order PID Control for Temperature Regulation of an Alkaline Water Electrolyzer Using Genetic Algorithm-Based Tuning

Abstract Alkaline water electrolysis (AWE) is a mature technology for high-purity hydrogen production, but its efficient and safe operation depends critically on accurate temperature regulation. Although higher operating temperatures may improve efficiency, they also accelerate component degradation, whereas lower temperatures reduce hydrogen production performance. Temperature control is therefore a key issue in AWE systems. This paper addresses the temperature regulation problem of an alkaline water electrolyzer through the design of a fractional-order PID (FO-PID) controller. The controller design is based on the transfer function obtained by linearizing a phenomenological nonlinear plant model around a selected operating point. A genetic algorithm-based frequency-domain tuning methodology is proposed, in which the controller parameters are determined so as to satisfy prescribed crossover-frequency and phase-margin specifications, together with additional constraints on the sensitivity and complementary sensitivity functions. The proposed controller is validated in simulation on the original nonlinear model under nominal and disturbed operating conditions, and its performance is compared with that of a classical PID controller and an alternative FO-PID controller tuned using a frequency-domain methodology. The evaluation is carried out in terms of settling time, overshoot, integral of squared error, and disturbance-rejection capability. The results show that the proposed GA-tuned FO-PID controller provides improved closed-loop performance relative to both comparison controllers, indicating that it is a promising alternative for temperature regulation in alkaline water electrolysis systems.