Dynamic Interaction of an Intergrated Doubly-Fed Induction generator and a Fuel Cell connected to Grid

For the past decade, the deregulation of the electric power industry has created an environment where traditional generation is being reexamined and new forms of generation are being created. Most likely wind turbines and fuel cells will be the dominant grid connected distributed generators. This paper proposes a novel integration of a doubly-fed induction generator (DFIG) and a fuel cell. With the proposed scheme, it is possible to inject power from a DC power source like a fuel cell into the AC grid without using an expensive inverter. The fuel cell is connected across the DC link of the back-back converters of a DFIG and power from the fuel cell is either injected into the generator or the grid depending upon wind conditions and energy requirements at the site. This is achieved by a low voltage DC link which also results in considerable savings. Dynamic models of DFIG and fuel cell have been derived which are used to simulate the proposed integrated system. Vector control schemes to operate the DFIG both as a power source and as an active filter compensating for harmful harmonics generated by non-linear loads are described. It has been shown that active and reactive power generated can be controlled. Power factor correction and reactive power control can also be achieved. Complete system has been simulated in Matlab/Simulink. Simulation results showing interaction of DFIG and fuel cell with the AC grid have been presented. Power flow between these systems has been analyzed