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Resonance Frequency Detection Technique in Grid-connected Inverter Systems Based on Double-order Digitalized Filter

Lookup NU author(s): hamza Khalfalla, Dr Salaheddine Ethni, Nasiru Kadandani, Professor Volker Pickert



This is the authors' accepted manuscript of a conference proceedings (inc. abstract) that has been published in its final definitive form by IEEE, 2019.

For re-use rights please refer to the publisher's terms and conditions.


Voltage source inverters (VSI) employed in distribution generation systems are usually interfaced to the grid via a low-pass LCL filter. This filter has a resonance frequency peak which can vary with respect to grid impedance, leading to instability issues if not properly suppressed. This paper proposes a resonance detection method based on a double-order digital band-pass filter. The digital filter extracts only the harmonic components around the resonance frequency from the injected grid current waveform while attenuating other frequencies outside its passband. The range of resonance frequencies has been determined by a grid impedance estimation technique. The detection method has been implemented in an experimental single-phase grid-connected inverter system and the practical results validate the effectiveness of the proposed method.

Publication metadata

Author(s): Khalfalla H, Ethni S, Kadandani N, Pickert V

Publication type: Conference Proceedings (inc. Abstract)

Publication status: Published

Conference Name: 10th International Renewable Energy Congress (IREC)

Year of Conference: 2019

Online publication date: 26/03/2019

Acceptance date: 02/04/2018

Date deposited: 04/04/2019

Publisher: IEEE