Primary power/frequency control with wind turbines and fuel cells

The increasing penetration of variable speed wind turbines in the electricity grid results in a reduction of the number of connected conventional power plants. This requires changes in the way the grid frequency is controlled. Together with the wind turbines devices like fuel cells can be installed, which can be used to supply the primary frequency control contribution of the wind turbines. In this paper it is analyzed how large the installed capacity of fuel cells should be to enable a correct response to frequency deviations. When fuel cells have stored hydrogen available, their response to changes in the power setpoint is fast. When the hydrogen has to be obtained from natural gas, or other fuels, their response is much slower. In that case the kinetic energy stored in the rotating mass of wind turbines can be used to support primary frequency control for a limited time period. The proposed control schemes are shown with the simulation of two case studies