Decentralized control of a fuel cell ultra-capacitor hybrid network

This paper addresses decentralized control of a simple hybrid power system consisting of a single fuel cell and an ultra-capacitor. This work develops separate controllers for the fuel cell and the ultra-capacitor, rather than a centralized controller. With a goal developing a control paradigm that is scalable to many energy resources connected to a network, the controllers are designed primarily to use locally sensed information. Explicit communication between controllers, such as exchange of locally sensed information, is absent. An energy conservation based approach, combined with a current regulation method developed by the authors in their earlier work [1], is used for transient control of the fuel cell. The control of state-of-charge of the ultra-capacitor is also principally governed by energy conservation, but implemented using two different approaches. One is based on dissipation, and the other is based on voltage modulation. The former is a conservative approach, while the latter is potentially more energy efficient. Simulation results are presented to demonstrate these concepts. Further research is ongoing to develop a detailed analytical base for this work.