Design and Simulation of a Fuel Cell Power Conditioning System Connected to a Weak Grid to Enhance Current Quality
مجید حسین پور
1
(
)
Hadi Khorramdel
2
(
Department of Electrical Engineering, University of Mohaghegh Ardabili, Ardabil, Iran
)
Mehdi Shahparasti
3
(
School of Technology and Innovations, Electrical Engineering, University of Vaasa, Vaasa, Finland.
)
Keywords: fuel cell, Grid connected inverter , impedance shaping, LCL filter, weak grid,
Abstract :
In grid-connected inverters, the quality of the current injected into the grid is significantly affected by the harmonics present in the common connection point voltage. Typically, to address the harmonics issue in this voltage, the coupling voltage feedforward impedance shaping method is applied to the grid-connected inverter. However, this method introduces a 90-degree phase delay in the inverter's output impedance, which corresponds to the matching phase delay of the grid-connected inverter. This issue is exacerbated by weak network conditions. This article proposes a novel virtual impedance shaping method grounded in frequency division to tackle this problem and enhance the quality of the power injected by grid-connected inverters based on fuel cells with an LCL filter. This method modifies the output impedance of the fuel cell-based grid-connected inverter to achieve different orders with varying coefficients across different frequency bands. The article thoroughly investigates the fundamental principles, theoretical analysis, design parameters, and application analysis of this method. With the proposed design, the inverter can effectively target common junction voltage harmonics while also demonstrating strong compatibility with a wide range of weak grid impedances. Finally, the simulation of the grid-connected inverter was conducted in the Simulink/MATLAB environment. The findings from both the theoretical analysis and simulation validate the efficiency and optimal performance of the proposed method. It confirms its effectiveness in injecting fuel cell power into the grid, improving the quality of the injected current, and enhancing stability in weak grid conditions.
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