Multi-coordination of actuators for a highly integrated, tightly coupled advanced power system was evaluated using the Hybrid Performance (Hyper) project facility at the U.S. Department of Energy’s National Energy Technology Laboratory (NETL). A two-by-two scenario in a fuel cell, turbine hybrid power system was utilized as a representative problem in terms of system component coupling during transients and setpoint changes. In this system, the gas turbine electric load is used to control the turbine speed, and the cold air bypass valve regulated fuel cell cathode mass flow.
Perturbations in the turbine speed caused by variations in the waste heat from the fuel cell affect the cathode airflow, and the cold-air bypass control action required for constant cathode airflow strongly affects the turbine speed. Previous implementation of two single-input, single-output (SISO) controllers failed to provide acceptable disturbance rejection and setpoint tracking under these highly coupled conditions. A multiple-input, multiple-output (MIMO) controller based on the classic internal model control (IMC) concept was implemented and experimentally tested for the first time using the Hyper project facility.
The state-space design of the MIMO configuration, the control law integration into the digital control platform, and the experimental comparison with the SISO case are presented.