All-Pass-Filter-Based Active Damping for VSCs With LCL Filters Connected to Weak Grids

LCL filters are commonly used to connect voltage-sourced converters (VSCs) to the grid. This type of filter is cheaper than a single inductor for the same current total harmonic distortion (THD), but it generates resonance problems if no active or passive damping method is applied. Active damping me...

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Bibliographic Details
Published in:IEEE transactions on power electronics 2018-11, Vol.33 (11), p.9890-9901
Main Authors: Roldan-Perez, Javier, Bueno, Emilio J., Pena-Alzola, Rafael, Rodriguez-Cabero, Alberto
Format: Article
Language:English
Subjects:
AC-DC power converters
Active damping
Computer simulation
Control algorithms
Control methods
Control systems
Control systems design
Converters
current control
Current measurement
Damping
Harmonic distortion
Power conversion
Resonant frequency
Robustness
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Summary:LCL filters are commonly used to connect voltage-sourced converters (VSCs) to the grid. This type of filter is cheaper than a single inductor for the same current total harmonic distortion (THD), but it generates resonance problems if no active or passive damping method is applied. Active damping methods are becoming popular in the literature because they improve efficiency, but they are sometimes difficult to implement and additional measurements are required. This paper proposes an active damping method for VSCs connected to weak grids, which is based on making the open-loop phase zero at the resonance frequency. It will be shown that this strategy provides adequate damping of oscillations and that it can be achieved in two different ways: at the design stage (if the design constraints make it possible) or with an all-pass filter in series with the current controller. Two methods to design the all-pass filter are proposed. Also, the proposed active damping technique is compared with three alternatives already proposed in the literature. All the control algorithms are verified by simulation and in a 15-kW prototype of a three-phase VSC connected to a configurable weak grid via an LCL filter.
ISSN:0885-8993
1941-0107
DOI:10.1109/TPEL.2017.2789218