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Self-commissioning Notch Filter for Active Damping in Three Phase LCL-filter Based Grid Converters
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| Author(s) |
Rafael PENA-ALZOLA, Marco LISERRE, Frede BLAABJERG, Tamas KEREKES |
| Abstract |
LCL-filters are used to mitigate the harmonic current content in grid converters. The LCL-filter resonancemust be damped in order to avoid stability problems in the current control. Active damping avoidsresistors at the expense of increased control complexity. Large grid impedance variations can challengethe LCL-filter stability. Active damping by using a notch filter on the reference voltage for the modulatoris simple to implement and does not require additional sensors. With the notch frequency tuned for theresonant frequency the voltage reference does not contain any component susceptible of exciting theLCL-filter. However, the notch filter tuning requires considerable design effort and the variations in theresonance frequency limit the LCL-filter robustness. This paper proposes a simple tuning procedure forthe notch filter that results in proper robustness. In order to cope with the grid inductance variations itis proposed to estimate the resonance frequency by means of Fourier analysis. The Goertzel algorithm,instead of the FFT, is used to reduce the calculation and memory requirements. Thus, the proposedself-commissioning notch filter results robust and consumes little computational resources. Finally, theanalysis is validated with both simulation and experiments. |
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| Filename: | 0343-epe2013-full-09572675.pdf |
| Filesize: | 1.187 MB |
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| Type |
Members Only |
| Date |
Last modified 2014-02-09 by System |
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