DocumentCode :
708454
Title :
Active damping of LLCL-filter resonance based on LC-trap voltage and capacitor current feedback
Author :
Min Huang ; Xiongfei Wang ; Poh Chiang Loh ; Blaabjerg, Frede
Author_Institution :
Dept. of Energy Technol., Aalborg Univ., Aalborg, Denmark
fYear :
2015
fDate :
15-19 March 2015
Firstpage :
2903
Lastpage :
2910
Abstract :
The LLCL-filter is emerging into grid-connected converters due to a smaller size compared to the conventional the LCL-filter. Similar to LCL-filter, the high order resonance introduces potential instability to the overall system which should be properly damped either passively or actively. In this paper, different feedback coefficients like the proportional, derivative, integral, high pass and low pass feedback coefficients of the filter capacitor current and the LC-trap circuit voltage are investigated for damping the filter resonance. Active damping methods are analyzed by using the concept of the equivalent impedance with and without the delay effect of an LLCL-filter based gridconnected inverter. Their corresponding equivalent circuits for the purpose of resonance damping are given to identify whether the feedback coefficient should be negative or positive for the different state-feedback methods. Then the stability of the different methods and the design of the feedback coefficient are analyzed and compared using root loci. Finally, experimental results are presented to validate the theoretical analysis.
Keywords :
LC circuits; equivalent circuits; invertors; power filters; power grids; LC-trap circuit voltage; LC-trap voltage; LLCL-filter resonance; active damping method; capacitor current feedback; equivalent circuits; equivalent impedance; feedback coefficients; filter capacitor current; grid-connected inverter; resonance damping; state-feedback method; Capacitors; Damping; Delays; Impedance; Inverters; Power harmonic filters; Resonant frequency; Active damping; LLCL-filter; delay; different feedback coefficients; grid-connected converter; grid-side current control; impedance-based design;
fLanguage :
English
Publisher :
ieee
Conference_Titel :
Applied Power Electronics Conference and Exposition (APEC), 2015 IEEE
Conference_Location :
Charlotte, NC
Type :
conf
DOI :
10.1109/APEC.2015.7104763
Filename :
7104763
Link To Document :
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