Derivative-dependent control of a fuel cell system with a safe implementation: An artificial delay approach

The growing demand for energy in recent decades has been followed by an increasing interest in clean energy sources as means to mitigate environmental pollution. Accordingly, renewable energy systems are required to not only guarantee safe operation but also have the ability to regulate their responses dynamically against operational variations and disturbances. Here, we propose a derivative-dependent controller to optimize this dynamic response in a fuel cell system. Since derivatives are in general difficult to measure or construct reliably, it is common practice to approximate them using finite-differences. This approximation, if not performed carefully, may produce undesired control activity and even instability. In this article, we propose to systematically engineer the finite-differences using artificial delays so as to avoid those undesired outcomes. This therefore guarantees a safe implementation of the control scheme. The objective of the proposed controller is to regulate the fuel cell's output voltage while quickly compensating for parametric variations and unknown disturbances without the need of explicitly measuring or estimating them. Simulation results verify the advantages of the approach demonstrating that the controller with artificial delays is a preferable substitute for ideal derivative-dependent control implementations in fuel cell applications.