Özet:

Fuel cell system is a promising alternate way of power generation from clean, green fuel such as Hydrogen with almost zero emissions. It can be a primary power or an aiding power to the grid during instability. Grid connected fuel cell systems experience double line frequency ripples from the inverters which affect the life of fuel cells. The current ripples are to be limited within 15% for safe operation of the fuel cells. This paper presents design of a dual active bridge DC-DC converter to step up the low voltage DC output from fuel cell to a high voltage DC with galvanic isolation and a PLL based grid synchronized single phase PWM inverter with dq reference frame grid current control suitable for fuel cell systems. Extended Symmetrical Optimum method is used for optimal tuning of the PI controllers. An LCL filter is designed for effective ripple attenuation in the grid current with active damping of the resonance in the region of stability. MATLAB/Simulink® is used for the design and is verified with a 1kW Horizon PEM fuel cell system. The power is exported to the grid with measured THDi of 1.7% in the grid current with reactive power injection by simple phase shift modulation control. The maximum overall system efficiency is measured to be 85%.

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