Dynamics and Control of Solid Oxide Fuel Cell Systems for Meeting Transient Demand in Distributed Generation Applications

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Dynamically dispatched power plants are required for the increasingly distributed nature of power generation. This ability to meet demand transients is key to developing safe, resilient and independent power networks, in response to natural or man-made disruptions. Furthermore, it is desirable for systems to be able to run at partial load without large losses in efficiency or performance. Partial load operation may occur, for example, to provide power to a small group of geographically remote users, or to make up for the variable power output from other forms of generation. Solid oxide fuel cells offer high efficiency, ultra-low pollutant emissions, and scalability and flexibility for distributed generation. However, while fuel cells are capable of tracking fast power variations, they are not used in this fashion due to important technical challenges, including dynamic preheating and processing of the fuel and oxidant, and the inability to control the fuel cell temperature profile dynamics. The current project seeks to overcome these limitations with innovations in fuel cell system design and control for dynamic operation, toward enhanced levels of reliability as well as reduced costs. This project includes fuel cell system designs, system level dynamic simulations, and new control techniques to enable fuel cell systems to become a key, if not the preferred, dynamically dispatched technology. This project aims at developing a better understanding of the issues faced in, and developing solutions for, fast dynamic operation of high temperature fuel cell systems. Using advanced control techniques, and exploiting under-used flexibilities in the overall system design, could produce significant improvements in dynamic operation and thermal management. Different fuel cell configurations (co-flow, counter flow and cross flow) will be studied and evaluated. Three major tasks will be accomplished: (i) development of high fidelity models with significant spatial resolution for dynamic controller design computations, (ii) evaluation of system designs for separating decoupled control loops, identifying new mechanisms for actuation and sensing, and developing a variety of control strategies, and (iii) application of performance oriented anti-windup techniques to enable controllers designed for key subsystems to withstand occasional saturation without much performance compromise. Degradation and life-cycle analysis will be used to evaluate the effectiveness of the approaches. Project will produce reliable dynamic models and a systematic approach to design and control fuel cell systems to enable higher, and reliable, renewable power use.