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

Peña-Alzola, Rafael; Roldán-Pérez, Javier; Bueno, Emilio; Huerta, F.; Campos‐Gaona, David; Liserre, Marco; Burt, Graeme

doi:10.1109/tpel.2018.2801126

Cited by 26 publications

(18 citation statements)

References 41 publications

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“…Thanks to the fact that it greatly eases the controller design, nowadays the Bode stability criterion is still commonly used in many types of systems, such as power electronic converters [4]- [8], [11], [12], [14], [16], [22], [23]. However, this criterion has a limited applicability range, which means that the criterion is only valid under certain application conditions, given the fact that it is based on specific cases of the Nyquist criterion.…”

Section: Introductionmentioning

confidence: 99%

On the Stability of Advanced Power Electronic Converters: The Generalized Bode Criterion

Lumbreras

Barrios

Urtasun

et al. 2019

IEEE Trans. Power Electron.

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A key factor in the design of power electronic converters is the development of control systems and, in particular, the determination of their stability. Due to ease of application, the Bode criteria are currently the most commonly used stability criteria, both with regard to its classic version and to the subsequent revisions proposed in the literature. However, as these criteria have a limited range of applicability, on occasions it is necessary to resort to other universally applicable criteria such as the Nyquist criterion. Unlike Bode, the Nyquist criterion can always be applied, although its use considerably complicates the tuning of the controller. This paper proposes a new stability criterion, called Generalized Bode Criterion, which is, on the one hand, based on the Nyquist criterion, and therefore always applicable, and, on the other hand, calculated from both the Bode diagram and the 0 Hz phase of the open-loop transfer function, thus making the criterion easy to be applied. This way, the proposed criterion combines the advantages of Nyquist and Bode criteria and provides an interesting and useful tool to be applied to the controller design process. The criterion is validated by means of simulation and experimental tests made on a voltage control loop for a stand-alone PV system including a battery, a boost converter, an inverter and an ac load. The tests are also used to show the limitations of the classic Bode criterion and its revisions to correctly determine the stability of complex systems.

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Section: Introductionmentioning

confidence: 99%

On the Stability of Advanced Power Electronic Converters: The Generalized Bode Criterion

Lumbreras

Barrios

Urtasun

et al. 2019

IEEE Trans. Power Electron.

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“…By inserting a digital filter with special function in the forward path of current control loop, the LCL-filter resonance peak can be damped by using the filter-based damping method, without any additional sensors and passive components. The filters mainly include the notch filter [33], [79]- [84], the low-pass filter (LPF) [33], and the all-pass filter [85].…”

Section: B Filter-based Damping Methodsmentioning

confidence: 99%

Modeling and Stability Analysis of $LCL$ -Type Grid-Connected Inverters: A Comprehensive Overview

et al. 2019

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Due to the advantages of superior harmonics attenuation ability and reduced size, the LCL filter has been widely adopted to interface between the inverter and the grid for improving the quality of injected grid currents. However, the high-order characteristics and various constraints of the LCL filter complicate the filter design. Moreover, the stability of the internal current control loop of the individual inverter is susceptible to the inherent LCL-filter resonance peak. Meanwhile, the overall system stability would be aggravated by the external interactions between the inverter and the weak grid as well as among the paralleled inverters. Both the LCL-filter resonance peak and two types of interaction would cause severely distorted grid currents. Motivated by the existing problems, a comprehensive review on the modeling and stability analysis of the LCL-type grid-connected inverters is conducted in this paper. Concretely, the generalized parameter constraints of the LCL filter are outlined to facilitate the passive components selection, and the magnetic integration techniques of filter inductors are also introduced to reduce the weight and size of filter for increasing the power density of the system. Then, the various damping methods for enhancing the individual internal stability and the relevant application issues are also discussed. Furthermore, the impedance-based method for evaluating the system-level interactive stability is subsequently reviewed, with the emphasis on different modeling methods of inverter output impedance and online impedance measurement techniques. Finally, the future research trends on the modeling and stability analysis of LCL-type grid-connected inverters are also presented. INDEX TERMS LCL-filter, grid-connected inverters, parameters design, magnetic integration, damping methods, delay, stability, impedance-based stability analysis, impedance modeling, impedance measurement. I. INTRODUCTION Recently, the distributed power generation systems (DPGS), as shown in Fig. 1, have been widely utilized for renewable energy integration, such as solar, wind, and fuel cell, which greatly alleviate the energy crisis and environmental problems [1]-[5]. Grid-connected inverters controlled by pulse-width modulation (PWM) techniques play the key roles The associate editor coordinating the review of this article and approving it for publication was Madhav Manjrekar.

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“…An intuitive design criterion would be to place the notch filter at the resonance frequency (ω n f = ω res , being ω res the resonance frequency of Z g ), in order to cancel out the resonance peak, meanwhile ξ z and ξ p set the width and the depth of the notch. A robust design is achieved when the width of the notch is selected to account for possible deviations of the resonance frequency [21], [23], [25]. Then ξ z and ξ p are selected to account for a 10% resonance frequency deviation (∆ω = 0.1ω res ) and an attenuation in the frequency range of ω res ± ∆ω equal to the resonance peak (cf.…”

Section: B Design Of Current Controller With Notch Filtermentioning

confidence: 99%

“…On the other hand, notch-filters introduce and anti-resonance peak that aims to cancel out the resonance of the LCL filter. The notch is typically placed at the resonance frequency of the LCL filter [21], [23], [25] and the damping of the poles and zeros are used to determine the depth and width of the notch. A different approach is to place the anti-resonance peak of the notch filter separated from the expected LCL resonance frequency, in order to account for possible resonance frequency drifts due to change in the physical parameters [22].…”

Section: Introductionmentioning

confidence: 99%

Analysis and Comparison of Notch Filter and Capacitor Voltage Feedforward Active Damping Techniques for LCL Grid-Connected Converters

Rodriguez-Diaz

Freijedo

Vasquez

et al. 2019

IEEE Trans. Power Electron.

103

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The use of LCL filters is a well accepted solution to attenuate the harmonics created by the pulsewidth modulation (PWM). However, inherently LCL filters have a resonance region where the unwanted harmonics are amplified, which can compromise stability. Several techniques have been developed in order to tackle this issue. At first the use of passive damping, by intentionally increasing the resistance of the LCL filter components, is a simple, robust and straightforward solution; however, it decreases the overall efficiency of the system, so in general is unwanted. Alternatively, active damping strategies, where the resonance damping is provided by the current controller, are of major interest. This paper analyses the robustness of the closedloop dynamics when different active damping techniques are implemented. The analysed active damping techniques, which have been selected because of their readiness and simplicity, are: 1) filtered capacitor voltage feed-forward and 2) second order filters in cascade with the main current controller. The impedance/admittance stability formulation is used to model the system, which has been proven to be very convenient for the assessment of robustness. Experimental tests are provided in order to show the accuracy of the analysis and verify the findings. This paper proves that filtered capacitor voltage feed-forward is more robust and reliable solution than implementations based on cascade notch filters.

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

Cited by 26 publications

References 41 publications

On the Stability of Advanced Power Electronic Converters: The Generalized Bode Criterion

On the Stability of Advanced Power Electronic Converters: The Generalized Bode Criterion

Modeling and Stability Analysis of $LCL$ -Type Grid-Connected Inverters: A Comprehensive Overview

Analysis and Comparison of Notch Filter and Capacitor Voltage Feedforward Active Damping Techniques for LCL Grid-Connected Converters

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