1 Department of Energy Technology, The Faculty of Engineering and Science, Aalborg University, VBN2 The Faculty of Engineering and Science (ENG), Aalborg University, VBN3 Power Electronic Systems, The Faculty of Engineering and Science, Aalborg University, VBN4 Shanghai Maritime University5 Shanghai Maritime University
This paper investigates the maximum and the minimum gain of the proportional resonant based grid current controller for a grid-tied inverter with a passive damped high-order power filter. It is found that the choice of the controller gain is limited to the local maximum amplitude determined by Q-factor around the characteristic frequency of the filter and grid impedance. To obtain the Q-factor of a high-order system, an equivalent circuit analysis method is proposed and illustrated through several classical passive damped LCL- and LLCL-filters. It is shown that both the RC parallel damper that is in parallel with the capacitor of the LCL-filter or with the Lf-Cf resonant circuit of the LLCL-filter, and the RL series damper in series with the grid-side inductor have their own application limits. Thus, a composite passive damped LLCL-filter for the grid-tied inverter is proposed, which can effectively suppress the possible resonance in case that the grid impedance varies in a wide range. Simulation results are good agreement with the theoretical analysis.
Proceedings of the 3rd Ieee International Symposium on Power Electronics for Distributed Generation Systems, 2012, p. 759-766
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3rd International Symposium on Power Electronics for Distributed Generation Systems, 2012