Experimental Investigation of the Frequency Response of an LC-Filter and Power Transformer for Grid Connection

Christoffer Fjellstedt (), Johan Forslund and Karin Thomas
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Christoffer Fjellstedt: Division of Electricity, Department of Electrical Engineering, Uppsala University, 752 37 Uppsala, Sweden
Johan Forslund: Division of Electricity, Department of Electrical Engineering, Uppsala University, 752 37 Uppsala, Sweden
Karin Thomas: Division of Electricity, Department of Electrical Engineering, Uppsala University, 752 37 Uppsala, Sweden

Energies, 2023, vol. 16, issue 15, 1-12

Abstract: The power delivered by a voltage source inverter needs to be filtered to fulfill grid code requirements. A commonly used filter technology is the LCL-filter. An issue with the LCL-filter is the occurrence of a resonance peak, which can be mitigated with active or passive damping methods. The transfer function of the filter is often used to investigate the frequency response of the system and propose damping methods. The use of an LC-filter combined with a power transformer to form an LCL-filter has not been extensively investigated. Therefore, the study in this article introduces a model for an LC-filter and power transformer for the grid connection and a derived transfer function for the model. The transfer function for the system is validated with simulations and experimental investigations. The results from simulations and the results from a direct solution of the derived analytical function overlap almost perfectly. The magnitudes of the experimental results are approximately 1 dB lower than the simulation and analytical results before the resonance frequency. At the resonance frequency, the experimental results are approximately 13.4 dB lower. The resonance frequency, however, occurs at approximately the same frequency. It is also concluded that the system is significantly damped.

Keywords: LC-filter; LCL-filter; power transformer; grid connection; renewable energy (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2023
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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