PID Control Design and Demonstration Using a Cyber-Physical Fuel Cell/Gas Turbine Hybrid System

The emphasis on traditional control in power systems has traditionally focused on the application of first order transfer functions to develop gains in distributed PI or PID control. The application of traditional PI or PID control in fuel cell turbine hybrid power systems for setpoint tracking or disturbance rejection during transient operation has proved to be challenging because the interaction and nonlinearities. In this work, a systematic approach to specifying ideal gains for PID control was established and then applied to hybrid systems using the cyber-physical emulation facility at the National Energy Technology Laboratory. Through testing on hardware, it was proved that the control variable response to actuator modulation was not first order. By developing second order transfer functions to specify gains, the response of the system was predicted as expected by simulation. Testing of a hot air bypass valve to control fuel cell cathode airflow setpoint tracking and disturbance rejection was effectively demonstrated with response behaviors as expected, rise times under 3.5 seconds, and overshoot predicted for the underdamped case.