Location

This example model can be found in the software under the category "Renewable Energy" with the file name "Fuel_Cell_Generation_System.ecf".

Description

In this example a fuel cell generation system (FCGS) is modeled. The FCGS is connected to a typical distribution system and several tests are performed demonstrating the FCGS operation following the active and reactive power references. The interface converter of the FCGS is an average model.

The figure shows the simulation of a 45 kW fuel cell generation system (FCGS) connected, via a feeder, to a simplified three bus 22.9 kV, 50 Hz distribution system. The feeders are modeled with their equivalent direct sequence and zero sequence impedances. Bus3 in the model has two loads of 0.5244 MW and 0.1669 MVAr connected to it.

The FCGS is connected to Bus4 via a 22.9 kV/480 V, 60 kVA star-delta distribution transformer. The transformer secondary is connected to the voltage source converter with a 1.5 mH choke filter.  The value of the choke filter selected was designed to limit the total harmonic distortion of the FCGS current injected into the grid at 5 % for the switching frequency of 1350 Hz (although the average model does not simulate the switching harmonics). The value of the parameters shown in the figure are detailed in the table. The inverter is responsible of controlling the active and reactive power at the point of common coupling (PCC). The FCGS is controlled in grid following mode where it is capable of tracking active and reactive power references.

For more details about the FCGS model please refer to Fuel Cell Generation System (FCGS).

Simulation and Results

The following scenarios demonstrate the modes of operation of the FCGS described in Fuel Cell Generation System (FCGS). The results are shown in the figure below. The sequence of the mode change is shown in the table below.

The power references were chosen to demonstrate the capability of the FCGS to follow the references. The figures show that DC link voltage is regulated by the grid connected inverter. In the figure the active and reactive power references and measurements are shown. After 5 seconds, it can be seen that the reactive power is reduced to zero despite a non-zero reference. This happens because the control loop prioritizes the active power when respecting the converter power ratings. A similar observation can be made at 18 seconds when the active power reference is restored to 1 pu.

References

[1] Fuel Cell Markets (2017). NedStack PS50 PEM Fuel Cell System. 

[2] N. M., O. Tremblay and L. A. Dessaint, "A generic fuel cell model for the simulation of fuel cell vehicles," 2009 IEEE Vehicle Power and Propulsion Conference, Dearborn, MI, 2009, pp. 1722-1729