H/spl infin/ control design for a stationary fuel cell power plant

Control of fuel cell power plants is very challenging due to the transient nature of the loads and the preference towards simpler, integrated system design necessitated by cost reduction. We study here, the problem of coordinating the fuel and air flows into the fuel processor of a stationary PEMFC power plant based on the load requirement while ensuring proper regulation of the CPO (catalytic partial oxidation) reactor temperature and protecting the cell stack from hydrogen starvation. A linear model of the relevant dynamics is obtained from a nonlinear system level dynamic model. Model reduction is performed to obtain a linear model of tractable size. The open loop plant behavior is analyzed using relative gain array (RGA) and it is shown that loop interactions are significant away from DC. A multivariable Hinfin controller has been designed to optimize tracking and disturbance rejection performance. It is shown by simulations that the resulting controller adequately deals with loop interactions and improves transient performance. The order of the Hinfin controller is reduced without significant degradation in performance using controller order reduction methods