Sinusoidal current injection based on a line-commutated inverter for single-phase grid-connected renewable energy sources

Authors: MURAT ÜNLÜ, SABRİ ÇAMUR, ERSOY BEŞER, BİROL ARİFOĞLU

Abstract: This paper presents a new power electronic interface based line-commutated inverter (LCI) for dc power injection to the grid. The proposed system involves a simple power electronic converter and controller interface using a single-phase LCI. The controller has been developed that can inject a high quality sinusoidal current to the utility grid from the dc source. By this means, ac side harmonic filters and the harmonic cancellation technique are eliminated. The proposed system facilitates controlling the injected current with a controllable power factor of operation. The complete system has been modeled in MATLAB/Simulink and tested experimentally with the laboratory prototype. Finally, the simulation and the experimental results show good performance of the proposed LCI technique. The total harmonic distortion (THD) of the injected currents for the different power factors and reference current signals is achieved less than 5%, which meets the grid-connected standards. The proposed single-phase LCI inverter system is a good alternative to the dc power transfer from renewable energy sources (photovoltaic, fuel cell etc.) to the utility grid.

Keywords: Line-commutated inverter, sinusoidal current, grid-connected, renewable energy sources, total harmonic distortion

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