IMPROVING VOLTAGE SAG RIDE-THROUGH IN
HYBRID FUEL CELL / BATTERY DISTRIBUTED
GENERATION SYSTEMS
ABSTRACT
In this paper controller design for voltage sag ride-through in hybrid fuel
cell/energy storage distributed power generation system has been presented. As the
amount of fuel cell power generation and other Distributed Generation (DG) with
power electronic in the grid grows, it becomes unacceptable to disconnect generat-
ing units every time a disturbance occurs, as was common practice in he past.
Keeping the VSC on line during unbalanced voltage sags becomes thus a very
critical issue. Hence, modeling, controller design, and simulation study of a hybrid
distributed generation system are investigated. The physical model of the fuel cell
stack, battery energy storage and the dynamic models of power conditioning units
are described. Based on the classification of unbalanced faults that can occur in the
grid, resulting in voltage sags at the bus where the hybrid power system is con-
nected, the maximum current that the converter valves must be bale to withstand is
calculated. Simulation results are given to show the overall system performance
including active power control and voltage sag ride-through capability of the hy-
brid distributed generation system.