Fuel cell based distributed generation system

The paper presents a circuit model and controllers of fuel -cell -based distributed generation systems (DGS) in a standalone AC power supply. A dynamic model of the fuel cell is considered. To boost low -output DC voltage of the fuel cell to high DC voltage and to compensate for its slow response during the transient, two full-bridge DC-to-DC converters are adopted and their controllers are designed: a unidirectional full-bridge DC-to-DC boost converter for the fuel cell and a bidirectional full-bridge DC-to DC-buck/boost converter for the battery. For a three-phase DC-to-AC inverter, a discrete-time state space model in the stationary dq reference frame is derived, and two discrete-time-sliding mode controllers are designed: a voltage controller in the outer loop and a current controller in the inner loop.