Grid Impedance Estimation for Single Phase PV Grid Tide Inverter Based on Statistical Signal Processing Techniques

Khalfalla, H; Ethni, S; Shiref, M; Al-Greer, M; Pickert, V; Armstrong, M

doi:10.1109/UPEC.2018.8541874

Grid Impedance Estimation for Single Phase PV Grid Tide Inverter Based on Statistical Signal Processing Techniques

Lookup NU author(s): hamza Khalfalla, Dr Salaheddine Ethni, Dr Muez Shiref, Dr Maher Al-Greer, Professor Volker Pickert, Dr Matthew Armstrong

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Abstract

This paper presents an effective approach to detect the variation of the grid impedance for single phase PV grid connected inverter interfaced by LCL filter. The proposed technique entails the use of a digital Sallen-Key band pass filter placed at the point of common coupling (PCC) to filter out the harmonic components around the resonance frequency. Series of statistical signal processing steps are applied to the output signal of the band pass filter in order to identify the grid impedance variation. The techniques described in this paper can be deployed to tune the current controller gains using gain-scheduling method; it can also be utilized in islanding detection leading to power quality enhancement. MATLAB/Simulation results based on experimental data of PV grid inverter system subjected to wide range of impedance variation are presented to validate the proposed method.