Design and Modeling of an LCL-Type Single-Phase Grid-Connected Fuel Cell Power Injection System with an Improved Virtual Impedance-based Hybrid Active Damping Scheme

The use of renewable energy systems based on fuel cells is steadily increasing, among which the Proton Exchange Membrane Fuel Cell (PEMFC) has attracted the attention of researchers due to its advantages, including lower pollution, higher power output, and improved efficiency. To transfer the energy produced by fuel cells to the power grid, Voltage Source Inverters (VSIs) are utilized. However, these inverters generate high-order harmonics, which diminish the quality of the current injected into the grid. The use of LCL filters at the inverter output improves the quality of the injected current. However, these filters inherently suffer from resonance issues, which can compromise grid stability. To overcome this issue, this paper proposes an improved virtual impedance-based hybrid damping method. To enhance grid stability and solve the resonance problem, a hybrid active damping method is employed, which is based on capacitor voltage feedforward and inverter-side current feedback. This method, using capacitor voltage and inverter-side current sensors, can eliminate harmonics, improve the quality of the injected current into the network, and enhance system passivity and stability. A comparative study has been performed to assess different damping techniques in comparison with the proposed method. The performance of the single-phase grid-connected fuel cell power conditioning system with an LCL filter was evaluated under dynamic fuel cell flow variations using MATLAB/Simulink. The obtained results confirm the proper operation of the proposed system, demonstrating high-quality current injection into the grid while maintaining system stability. The THD of the injected current achieved with the proposed strategy is ۱.۰۶%.

کلیدواژه ها:

Fuel Cell ، Grid Stability ، Hybrid Damping ، LCL filter ، voltage source inverter