Abstract
The LCL filter represents the state-of-the-art passive interface type for grid tied power converters as a cost and space reducing alternative to single coil solutions for switching harmonic attenuation. However, a simple PI controller can cause instabilities when applied to control the current of this filter. Thus a general analytically closed approach is presented to determine the safe operating areas for both grid current control mode (GCM) and inverter current control mode (ICM), both with and without additional active damping feedback of the capacitor current. The proposed approach consequently applies the Nyquist criterion in the continuous frequency domain, facilitating the determination of very simple expressions of parameter stability limits. These design guidelines, which partially also confirm previous findings, are for the first time summarized all together as the results of proposed approach to aid corresponding controller design.
Highlights
LCL filters are commonly applied for the attenuation of switching harmonic content of the grid current of either single or three phase inverters
active damping (AD) has been presented as multiloop [1]–[9] or single loop solution
As a reduced number of sensors is preferable, single loop solutions emerged that apply additional phase lifting measures like leadlag elements and notch filters [12]–[15] or state observers [16]. The former approaches can all be summarized as attempts to implement an additional differential component to the single loop controller [17] while at the same time avoiding high frequency perturbation
Summary
LCL filters are commonly applied for the attenuation of switching harmonic content of the grid current of either single or three phase inverters. As a reduced number of sensors is preferable, single loop solutions emerged that apply additional phase lifting measures like leadlag elements and notch filters [12]–[15] or state observers [16]. BIERHOFF ET AL.: ANALYSIS AND DESIGN OF GRID-TIED INVERTER WITH LCL FILTER approach presented in [24] determines stability margins of the controller parameters in the continuous frequency domain while accounting for the computational delay time by a graphical solution. The presented contribution can be set apart from existing literature with respect to the following features: 1) Generality: A conducted stability analysis approach in continuous frequency domain combined with an a priori current controller design and justified model simplification facilitate the development of simple expressions for either filter or active damping design ensuring stable operation for any kind of control mode (GCM or ICM) or sampling frequency range.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
