Design of the PID temperature controller for an alkaline electrolysis system with time delays

TL;DR

This paper presents a method for designing PID temperature controllers for alkaline electrolysis systems that accounts for heat transfer delays, optimizing stability and response time through frequency-domain modeling and experimental validation.

Contribution

It introduces a thermal dynamic model in the frequency domain and optimizes PID parameters considering system delays and stability, improving temperature control in electrolysis systems.

Findings

Optimized PID parameters enhance temperature stability.

Using before-stack temperature feedback reduces fluctuations in small systems.

Using after-stack temperature improves economy in larger systems.

Abstract

Electrolysis systems use proportional-integral-derivative (PID) temperature controllers to maintain stack temperatures around set points. However, heat transfer delays in electrolysis systems cause manual tuning of PID temperature controllers to be time-consuming, and temperature oscillations often occur. This paper focuses on the design of the PID temperature controller for an alkaline electrolysis system to achieve fast and stable temperature control. A thermal dynamic model of an electrolysis system is established in the frequency-domain for controller designs. Based on this model, the temperature stability is analysed by the root distribution, and the PID parameters are optimized considering both the temperature overshoot and the settling time. The performance of the optimal PID controllers is verified through experiments. Furthermore, the simulation results show that the before-stack temperature should be used as the feedback variable for small lab-scale systems to suppress stack temperature fluctuations, and the after-stack temperature should be used for larger systems to improve the economy. This study is helpful in ensuring the temperature stability and control of electrolysis systems.