A Time Delay Compensation Method Based on Area Equivalence For Active Damping of an &lt;italic&gt;LCL&lt;/italic&gt; -Type Converter

Chen, Chen; Xiong, Jian; Wan, Zhiqiang; Ji, Lei; Zhang, Kai

doi:10.1109/tpel.2016.2531183

Cited by 141 publications

(80 citation statements)

References 29 publications

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“…Careful design of the digital controller must be exercised because of the computational and PWM delays. The analysis of the computational delay in the feedback loop of LCL-filter based inverters was analyzed in [6]- [8]. State-space control allows selecting the closedloop poles in the proper locations [9].…”

Section: Minimum Software Modifications No Additional Sensorsmentioning

confidence: 99%

See 1 more Smart Citation

Robust Active Damping in LCL-Filter-Based Medium-Voltage Parallel Grid Inverters for Wind Turbines

Peña-Alzola

Roldán-Pérez

Bueno

et al. 2018

IEEE Trans. Power Electron.

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This version is available at https://strathprints.strath.ac.uk/63375/ Strathprints is designed to allow users to access the research output of the University of Strathclyde. Unless otherwise explicitly stated on the manuscript, Copyright © and Moral Rights for the papers on this site are retained by the individual authors and/or other copyright owners. Please check the manuscript for details of any other licences that may have been applied. You may not engage in further distribution of the material for any profitmaking activities or any commercial gain. You may freely distribute both the url (https://strathprints.strath.ac.uk/) and the content of this paper for research or private study, educational, or not-for-profit purposes without prior permission or charge.Any correspondence concerning this service should be sent to the Strathprints administrator: strathprints@strath.ac.ukThe Strathprints institutional repository (https://strathprints.strath.ac.uk) is a digital archive of University of Strathclyde research outputs. It has been developed to disseminate open access research outputs, expose data about those outputs, and enable the management and persistent access to Strathclyde's intellectual output. Abstract-LCL-filter based grid-tie inverters require damping for current-loop stability. There are only software modifications in active damping, whereas resistors are added in passive damping. Although passive damping incurs in additional losses, it is widely used because of its simplicity. This article considers the active damping in medium-voltage parallel inverters for wind turbines. Due to cost reasons, only minimal software changes are allowed and no extra sensors can be used. The procedure must be robust against line-inductance variations in weak grids. Doubleupdate mode is needed so the resonance frequency is under the Nyquist limit. The bandwidth reduction when using active damping is also required to be known beforehand. Moreover, the design procedure should be simple without requiring numerous trial-and-error iterations. In spite of the abundant literature, the options are limited under these circumstances. Filter-based solutions are appropriate and a new procedure for tuning the notch-filter is proposed. However, this procedure requires that the resistance of the inductors is known and a novel filter-based solution is proposed that uses lag-filters. The lag-filters displace the phase angle at the resonance frequency so that the Nyquist stability criterion is fulfilled. Simulations and experiments with a 100 kVA prototype validate the analysis.

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Section: Minimum Software Modifications No Additional Sensorsmentioning

confidence: 99%

“…For this case as well it is required to use the low-frequency model that neglects the LCL-filter capacitor branch and uses the Padé approximant of the lag-filters in order to tune the PI controllers according to (8). Fig.…”

Section: B Novel Active Damping Procedures Based On Lag-filtersmentioning

confidence: 99%

Robust Active Damping in LCL-Filter-Based Medium-Voltage Parallel Grid Inverters for Wind Turbines

Peña-Alzola

Roldán-Pérez

Bueno

et al. 2018

IEEE Trans. Power Electron.

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“…A modified duty cycle generation method based on area equivalence proposed in [71] can also greatly reduce T d . The multi-sampling method in [72] can reduce the delay to some extent.…”

Section: Single-state Feedback Admentioning

confidence: 99%

LCL-resonance damping strategies for grid-connected inverters with LCL filters: a comprehensive review

Xie

2017

J. Mod. Power Syst. Clean Energy

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Grid-connected LCL-filtered inverters are commonly used for distributed power generators. The LCL resonance should be treated properly. Recently, many strategies have been used to damp the resonance, but the relationships between different damping strategies have not been thoroughly investigated. Thus, this study analyses the essential mechanisms of LCL-resonance damping and reviews state-of-the-art resonance damping strategies. Existing resonance damping strategies are classified into those with single-state and multi-state feedback. Singlestate feedback strategies damp the LCL resonance using feedback of a voltage or current state at the resonance frequency. Multi-state feedback strategies are summarized as zero-placement and pole-placement strategies, where the zero-placement strategy configures the zeros of a novel state combined by multi-state feedback, while the poleplacement strategy aims to assign the closed-loop poles freely. Based on these mechanisms, an investigation of single-state and multi-state feedback is presented, including detailed comparisons of the existing strategies. Finally, some future research directions that can improve LCL-filtered inverter performance and minimize their implementation costs are summarized.

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“…According to (9), an array of root loci for inner PI control loop considering inductance variation are drawn in Fig. 7.…”

Section: B Inner Pi Control Loopmentioning

confidence: 99%

“…The effect of sampling and PWM transport delays on the effectiveness of active damping methods has been investigated in [7], three distinct regions of LCL filter resonance have been identified. Compensating the delay in active damping loop can improve the system robustness, which can be achieved by shifting the capacitor current sampling instant towards the PWM reference update instant [8] or using the lead-lag compensator [9]. The optimal range of time delay and compensation method with single grid current feedback to improve the system performance has also been carefully studied [10].…”

Section: Introductionmentioning

confidence: 99%

Modeling and control of LCL-filtered grid-tied inverters with wide inductance variation

Xie

Zhang

et al. 2017

IECON 2017 - 43rd Annual Conference of the IEEE Industrial Electronics Society

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Abstract-Because of the low power losses and moderate cost, the magnetic powder cores are popular in producing the filtering inductors for the high efficient and cost-effective power converters. However, the soft magnetic property of the powder cores leads to the wide variation of inductance along with the changing of the inductor current in one cycle of the grid, which challenges the system stability and power quality. In this paper, the currentdependent small-signal model of a three-phase LCL-filtered inverter is derived for designing the corresponding controller. Based on the developed small-signal model, a capacitor current feedback based active damping loop and a fractional order repetitive control based compound current control loop are designed to stabilize the system and enhance the control accuracy in steady-state, respectively. The controller design procedure is given in detail. Finally, all-digital simulation has been conducted on a 3.7 kVA inverter system to verify the theoretical expectations.

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A Time Delay Compensation Method Based on Area Equivalence For Active Damping of an <italic>LCL</italic> -Type Converter

Cited by 141 publications

References 29 publications

Robust Active Damping in LCL-Filter-Based Medium-Voltage Parallel Grid Inverters for Wind Turbines

Robust Active Damping in LCL-Filter-Based Medium-Voltage Parallel Grid Inverters for Wind Turbines

LCL-resonance damping strategies for grid-connected inverters with LCL filters: a comprehensive review

Modeling and control of LCL-filtered grid-tied inverters with wide inductance variation

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