Ambient Temperature Impact on Pressurized SOFC Hybrid Systems

In this paper advanced control strategies based on Model Predictive Control (MPC) method are compared against a traditional PID controller in a Gas Turbine Pressurized SOFC hybrid system.A model of the integrated mGT-SOFC hybrid system has been developed to analyze the impact of ambient temperature changes on system performance and dynamic behaviour. Four different MIMO controllers (multi input multi output) based on a linearized system model have been implemented in order to control fuel cell temperature and power with different ambient temperatures. Fuel cell temperature is regulated by manipulating the cell by-pass mass flow, while power is regulated by changing the fuel cell electrical current and fuel mass flow (the fuel utilization factor is kept constant). Load following simulations have been carried out as follows: the same load ramp from 100% to 80% of fuel cell power and back has been set and studied under three different ambient conditions, 263K, 288K and 313K (−10°C, 15°C and 40°C).MPC demonstrated superior performance over the two distributed PID controls, thanks to the better setpoint tracking on the cell temperature, which is particularly evident when the ambient temperature deviates from the nominal condition. This is mainly explained by the capability of MPC in including the effects of non-linearities of the real system.Copyright © 2015 by ASME