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Journal ArticleDOI

Design and control of an LCL-filter-based three-phase active rectifier

30 Sep 2001-Vol. 41, Iss: 5, pp 1281-1291
TL;DR: In this article, a step-by-step procedure for designing the LCL filter of a front-end three-phase active rectifier is proposed to reduce the switching frequency ripple at a reasonable cost, while at the same time achieving a high-performance front end rectifier.
Abstract: This paper proposes a step-by-step procedure for designing the LCL filter of a front-end three-phase active rectifier. The primary goal is to reduce the switching frequency ripple at a reasonable cost, while at the same time achieving a high-performance front-end rectifier (as characterized by a rapid dynamic response and good stability margin). An example LCL filter design is reported and a filter has been built and tested using the values obtained from this design. The experimental results demonstrate the performance of the design procedure both for the LCL filter and for the rectifier controller. The system is stable and the grid current harmonic content is low both in the lowand high-frequency ranges. Moreover, the good agreement that was obtained between simulation and experimental results validates the proposed approach. Hence, the design procedure and the simulation model provide a powerful tool to design an LCL-filter-based active rectifier while avoiding trial-and-error procedures that can result in having to build several filter prototypes.
Citations
More filters
Journal ArticleDOI
09 Oct 2006
TL;DR: The proportional-resonant (PR) controllers and filters, and their suitability for current/voltage control of grid-connected converters, are described in this article.
Abstract: The recently introduced proportional-resonant (PR) controllers and filters, and their suitability for current/voltage control of grid-connected converters, are described. Using the PR controllers, the converter reference tracking performance can be enhanced and previously known shortcomings associated with conventional PI controllers can be alleviated. These shortcomings include steady-state errors in single-phase systems and the need for synchronous d-q transformation in three-phase systems. Based on similar control theory, PR filters can also be used for generating the harmonic command reference precisely in an active power filter, especially for single-phase systems, where d-q transformation theory is not directly applicable. Another advantage associated with the PR controllers and filters is the possibility of implementing selective harmonic compensation without requiring excessive computational resources. Given these advantages and the belief that PR control will find wide-ranging applications in grid-interfaced converters, PR control theory is revised in detail with a number of practical cases that have been implemented previously, described clearly to give a comprehensive reference on PR control and filtering.

1,483 citations

Journal ArticleDOI
TL;DR: In this paper, the authors analyze the stability problems of grid connected inverters used in distributed generation and demonstrate that the use of active damping helps to stabilise the system in respect to many different kinds of resonances.
Abstract: The aim of this paper is to analyze the stability problems of grid connected inverters used in distributed generation. Complex controllers (e.g., multiple rotating dq-frames or resonant-based) are often required to compensate low frequency grid voltage background distortion and an LCL-filter is usually adopted for the high frequency one. The possible wide range of grid impedance values (distributed generation is suited for remote areas with radial distribution plants) challenge the stability and the effectiveness of the LCL-filter-based current controlled system. It has been found out and it will be demonstrated in this paper that the use of active damping helps to stabilise the system in respect to many different kinds of resonances. The use of active damping results in an easy plug-in feature of the generation system in a vast range of grid conditions and in a more flexible operation of the overall system able to manage sudden grid changes. In the paper, a vast measurement campaign made on a single-phase system and on a three-phase system used as scale prototypes for photovoltaic and wind turbines, respectively, validate the analysis.

997 citations


Cites background from "Design and control of an LCL-filter..."

  • ...If a small resistor is inserted in series with the -filter capacitor in the -plane the result is the attraction of the unstable poles inside the unity circle [6]....

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  • ...The use of an -filter offers the possibility to reduce switching harmonics injection as well as to limit the value of the converter boost inductance decreasing encumbrance and mounting cost [6]–[8]....

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  • ...2) has already been described in [6] and [8]....

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  • ...If this is not the case the -filter effectiveness is reduced because at frequencies lower than the resonance frequency the filter behaves like the sum of its inductances [6]....

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  • ...Passive damping produces losses (they can be around 1% [6]) which especially in WT-turbine application systems can be unacceptable....

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Journal ArticleDOI
TL;DR: In this paper, a robust control strategy for regulating the grid current entering a distribution network from a three-phase VSI system connected via a LCL filter is proposed, which integrates an outer loop grid current regulator with inner capacitor current regulation to stabilize the system.
Abstract: Many grid connected power electronic systems, such as STATCOMs, UPFCs, and distributed generation system interfaces, use a voltage source inverter (VSI) connected to the supply network through a filter. This filter, typically a series inductance, acts to reduce the switching harmonics entering the distribution network. An alternative filter is a LCL network, which can achieve reduced levels of harmonic distortion at lower switching frequencies and with less inductance, and therefore has potential benefits for higher power applications. However, systems incorporating LCL filters require more complex control strategies and are not commonly presented in literature. This paper proposes a robust strategy for regulating the grid current entering a distribution network from a three-phase VSI system connected via a LCL filter. The strategy integrates an outer loop grid current regulator with inner capacitor current regulation to stabilize the system. A synchronous frame PI current regulation strategy is used for the outer grid current control loop. Linear analysis, simulation, and experimental results are used to verify the stability of the control algorithm across a range of operating conditions. Finally, expressions for ""harmonic impedance" of the system are derived to study the effects of supply voltage distortion on the harmonic performance of the system.

869 citations


Cites background from "Design and control of an LCL-filter..."

  • ...However, these filters require high switching frequencies to acceptably attenuate switching harmonics, particularly in weak-grid applications where the supply is sensitive to these harmonics....

    [...]

Journal ArticleDOI
TL;DR: In this paper, power converters are classified into single and multicell topologies, with attention to series connection and parallel connection either electrical or magnetic ones (multiphase/windings machines/transformers).
Abstract: The steady growth of installed wind power together with the upscaling of the single wind turbine power capability has pushed the research and development of power converters toward full-scale power conversion, lowered cost pr kW, increased power density, and also the need for higher reliability. In this paper, power converter technologies are reviewed with focus on existing ones and on those that have potential for higher power but which have not been yet adopted due to the important risk associated with the high-power industry. The power converters are classified into single- and multicell topologies, in the latter case with attention to series connection and parallel connection either electrical or magnetic ones (multiphase/windings machines/transformers). It is concluded that as the power level increases in wind turbines, medium-voltage power converters will be a dominant power converter configuration, but continuously cost and reliability are important issues to be addressed.

797 citations


Additional excerpts

  • ...Regarding filters, typically an LCL-filter is the adopted solution to attenuate PWM harmonics [33] but in the case a diode-bridge is adopted on the generator side and in the case of higher power WTS have also strict demands to grid voltage harmonics, trap filters might also be adopted....

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Journal ArticleDOI
TL;DR: In this paper, the authors give an overview and discuss some development trends in the technologies used for wind power systems, and several state-of-the-art wind turbine concepts, as well as the corresponding power electronic converters and control structures are reviewed, respectively.
Abstract: Wind power is still the most promising renewable energy in the year of 2013. The wind turbine system (WTS) started with a few tens of kilowatt power in the 1980s. Now, multimegawatt wind turbines are widely installed even up to 6-8 MW. There is a widespread use of wind turbines in the distribution networks and more and more wind power stations, acting as power plants, are connected directly to the transmission networks. As the grid penetration and power level of the wind turbines increase steadily, the wind power starts to have significant impacts to the power grid system. Therefore, more advanced generators, power electronic systems, and control solutions have to be introduced to improve the characteristics of the wind power plant and make it more suitable to be integrated into the power grid. Meanwhile, there are also some emerging technology challenges, which need to be further clarified and investigated. This paper gives an overview and discusses some development trends in the technologies used for wind power systems. First, the developments of technology and market are generally discussed. Next, several state-of-the-art wind turbine concepts, as well as the corresponding power electronic converters and control structures, are reviewed, respectively. Furthermore, grid requirements and the technology challenges for the future WTS are also addressed.

736 citations

References
More filters
Proceedings ArticleDOI
08 Oct 2000
TL;DR: In this article, the authors proposed a direct power control (DPC) of three-phase pulsewidth-modulated rectifiers without line voltage sensors, which is based on virtual flux (VF) estimation.
Abstract: In this paper, direct power control (DPC) of three-phase pulsewidth-modulated rectifiers without line voltage sensors is presented. The new system is based on virtual flux (VF) estimation. Theoretical principles of this method are discussed. The steady-state and dynamic behavior of VF-DPC are presented that illustrate the operation and performance of the proposed system compared to a conventional DPC method. Both strategies are also investigated under unbalance and predistorted grid. It is shown that the VF-DPC exhibits several advantages, particularly providing sinusoidal line current when the supply voltage is not ideal. Test results show the excellent performance of the proposed system.

688 citations

Journal ArticleDOI
TL;DR: In this paper, a control strategy for actively damping high-frequency resonance (above 1.5 kHz) in the input LC filter is presented, which prevents pollution of the utility by the current ripple due to the PWM switching.
Abstract: The voltage source converter (VSC) provides constant/controllable DC bus voltage, regenerating capability, controllable power factor, and nearly sinusoidal input current. If an input LC filter is added, it prevents pollution of the utility by the current ripple due to the pulsewidth modulation (PWM) switching. A novel control strategy for actively damping high-frequency resonance (above 1.5 kHz) in the input LC filter is presented. No additional sensors are required for the standard VSC. Theoretical results of the analysis and simulation are experimentally verified.

507 citations

Proceedings ArticleDOI
07 Nov 2002
TL;DR: In this article, the authors proposed a robust control strategy for regulating the grid current entering a distribution network from a three-phase VSI system connected via an LCL filter. But, the LCL filters require more complex control strategies and are not commonly presented in literature.
Abstract: Many grid connected power electronic systems, such as STATCOMs, UPFCs and distributed generation system interfaces, use a voltage source inverter (VSI) connected to the supply network through a filter. This filter, typically a series inductance, acts to reduce the switching harmonics entering the distribution network. An alternative filter is a LCL network, which can achieve reduced levels of harmonic distortion at lower switching frequencies and with less inductance, and therefore has potential benefits for higher power applications. However, systems incorporating LCL filters require more complex control strategies and are not commonly presented in literature. This paper proposes a robust strategy for regulating the grid current entering a distribution network from a three-phase VSI system connected via an LCL filter. The strategy integrates an outer loop grid current regulator with inner capacitor current regulation to stabilise the system. A synchronous frame PI current regulation strategy is used for the outer grid current control loop. Linear analysis, simulation and experimental results are used to verify the stability of the control algorithm across a range of operating conditions. Finally, expressions for "harmonic impedance" of the system are derived to study the effects of supply voltage distortion on the harmonic performance of the system.

449 citations


"Design and control of an LCL-filter..." refers background in this paper

  • ...Hence, the damping value is set to a similar order of magnitude as the series capacitor impedance at the resonant frequency [ 26 ]....

    [...]

  • ...... of the left side of the plane it is clear that the system is close to the border of the stability region without damping (zeros and poles numbered with 1 in Fig. 7). If a 10damping resistor is used then the system becomes more stable (zeros and poles numbered with 2 in Fig. 7). It is commented that stability analysis relating to resonance dynamics becomes less reliable as the sampling frequency approaches twice the resonant frequency [ 26 ]....

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  • ...Also, a disturbance can trigger a reaction from the closed-loop current controller (e.g., caused by a PWM modulator with a wide spectrum spread between the fundamental and the switching frequency harmonics, by an A/D characterized by poor resolution, by inadequate filters on the measured grid voltage [14], [ 26 ], or by an external disturbance such as a load connected to the same point of common coupling (PCC) [17])....

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Journal ArticleDOI
TL;DR: In this paper, the authors provide a common understanding of the EMI issues and provide simple pre-installation and post installation guidelines useful for all interested parries involved in the industry application of adjustable speed PWM invertor-fed AC motor drives.
Abstract: Electromagnetic interference (EMI) noise is defined as an unwanted electrical signal that produces undesirable effects in a control system, such as communication errors, degraded equipment performance and malfunction or nonoperation. This article provides a common understanding of the EMI issues and provides simple pre-installation and post-installation guidelines useful for all interested parries involved in the industry application of adjustable speed PWM invertor-fed AC motor drives.

419 citations


"Design and control of an LCL-filter..." refers background in this paper

  • ...A further issue for a VSC is high-frequency electromagnetic interference (EMI) (differential mode and common mode) [8], which needs specific filters (passive [9], [10] or active [11]) in frequency ranges above 150 kHz and rated at lower power...

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01 Jan 2002

346 citations