Monitoring Function based Extremum Seeking for Fuel Cell Energy Applications

Tiago Roux Oliveira¹; Téo Cerqueira Revoredo¹

¹ State University of Rio de Janeiro (UERJ)

doi:10.20906/CPS/COB-2015-1017

Resumo

The principles of Extremum Seeking (ES) were invented in the last century and it is one of the oldest feedback control methods. Rather than regulation, its purpose is real-time optimization. For this reason, applications of ES have often come from energy systems. In the ensuing decades, ES has been applied to gas turbines and even nuclear fusion reactors. Renewable energy applications have brought a new focus on the capabilities of ES algorithms, such as wind and solar energy. In this article, we present applications of ES in a different type of energy conversion systems for renewable energy sources: fuel cell systems. We introduce a new ES algorithm based on monitoring functions to control the current input of a fuel cell system subject to a constant air flow into the cathode. The method does not rely on knowledge of system modeling parameters, and adapt to changes in those parameters that occur due to disturbances and degradation. In a nutshell, the goal is the extraction of the maximum feasible energy from the system under uncertainty and in the absence of a priori modeling knowledge about the fuel cell system. The convergence rate of such a design to the maximum power point tracking is independent of the plant parameters, with tunable transient performance which is also independent of environmental conditions. We present simulation results that show the effectiveness of the proposed controller in comparison with the existing ES approaches.

Palavras-chave: maximum power point tracking; extremum seeking; renewable energy; fuel cell systems