Hello All
We using Grid connecetd Inverter using LCL Filter, we are unble damp low fréquences (like 200 hz to 350 hz)
Can you please suggest How to attenuates low frequencies for grid current ?
LCL filter values fixed, any other solution to attenuates low frequinces for control point view ?
Please find the attached FFT analysais PNG file for your reference.
To attenuate low frequencies in grid-connected inverters for grid current, consider employing Active Filtering to attenuate low-frequency components in the grid current selectively. Furthermore, techniques such as the Stockwell Transform or other time-frequency analysis methods can also be considered. These approaches provide a localized frequency representation of the signal, effectively reducing undesired low-frequency components.
Passive filters for these low frequencies are heavy and expensive. Active filters are affordable now.
A power passive filter is necessary to attenuate harmonics generated by the inverter. There are two types of passive filters for grid-connected inverter: L filter and LCL filter [3]. L filters play a role as a first-order low-pass filter (LPF) to attenuate the harmonics of the grid-side current.
Dear Kuruva Veeranna, I suggest you use some controller to reject specifically the harmonics you want. In the work entitled "A Direct Adaptive Controller With Harmonic Compensation for Grid-Connected Converters" ( DOI: 10.1109/TIE.2023.3270535 ), we showed how to reject specifically the harmonic contents of the 5th , 7th , 11th , and 13th of the fundamental component of the electrical grid. However, the proposed procedure is generalizable to any harmonic content you need. I hope it is useful for you. Best regards!
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