&lt;italic&gt;LLCL&lt;/italic&gt;-Filtered Grid Converter With Improved Stability and Robustness

Huang, Min; Wang, Xiongfei; Loh, Poh Chiang; Blaabjerg, Frede

doi:10.1109/tpel.2015.2467185

Cited by 76 publications

(34 citation statements)

References 30 publications

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“…It provides a sufficient, yet not necessary, stability condition for interconnected dynamic systems. A system will be stable and passive if each subsystem is passive seen from its terminal [27], [36], [37].…”

Section: A Passivity Of Single-loop Current Controlmentioning

confidence: 99%

Passivity-Based Stability Analysis and Damping Injection for Multiparalleled VSCs with LCL Filters

Wang

Blaabjerg

Loh

2017

IEEE Trans. Power Electron.

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188

114

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This paper addresses the harmonic stability resulting from the current-control interactions of the multiparalleled, LCLfiltered voltage-source converters. First, an alternative impedance model is proposed for the single-loop current control. The control output admittance of the converter is decomposed into a passive filter output admittance in series with an active admittance, which is dependent on the current controller and the time delay. The frequency-domain passivity theory is then applied to the active admittance for system stability analysis. It reveals that the stability region of the single-loop grid current control is not only dependent on the time delay, but affected also by the resonance frequency of the converter-side filter inductor and filter capacitor. Further on, the damping injection based on the discrete derivative controller is proposed to enhance the passivity of individual converters and thereby stabilizing the paralleled converters. Finally, simulation studies and laboratory tests validate the effectiveness of theoretical analysis and controller design.

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Section: A Passivity Of Single-loop Current Controlmentioning

confidence: 99%

Passivity-Based Stability Analysis and Damping Injection for Multiparalleled VSCs with LCL Filters

Wang

Blaabjerg

Loh

2017

IEEE Trans. Power Electron.

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188

114

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“…한편, 최근 개발된 LLCL 필터는 LCL 필터에 작은 인덕터를 추가하여 스위칭 주파수의 고조파 저감 특 성이 우수하다 [2]- [3] . 또한 LLCL 필터는 LCL 필터의 커패시터에 직렬로 작은 인덕터를 추가함으로써 계통 측 인덕터를 크게 줄일 수 있어 전체적으로 LCL 필 터보다 작게 설계할 수 있다 [4], [5] .…”

Section: 서 론unclassified

Stability Analysis of Current Control based on Virtual Resistor for Single-Phase Grid Converters with LLCL Input Filters

Bae¹,

Lee²

2016

The Transactions of the Korean Institute of Power Electronics

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To avoid the stability issues of LLCL filters, passive or active damping methods to eliminate the resonance phenomena are required. In this paper, system stability of a current control is analyzed when the active damping scheme based on the virtual resister is utilized in single-phase grid converter systems with LLCL input filters. The control performance according to the parameters of the virtual resistance is investigated. The validity of stability analysis was verified by simulation and experimental results.

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“…Typically, T d = 1.5T s (T s is the sampling period), thus f crit = f s /6 [11]- [13]. To retain a stable operation, the LCL filter should be carefully designed with its resonance frequency falling into the stable region [14], [15]. Note that a lower f r calls for larger filter inductors or filter capacitor, thereby f r > f s /6 would be most cost-effective.…”

Section: Introductionmentioning

confidence: 99%

A Highly Robust Single-Loop Current Control Scheme for Grid-Connected Inverter With an Improved LCCL Filter Configuration

Pan

Ruan

Xiongfei

et al. 2018

IEEE Trans. Power Electron.

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Abstract-Single-loop current control is an attractive scheme for the LCL-type grid-connected inverter due to its simplicity and low cost. However, conventional single-loop control schemes, which command either the inverter current or the grid current, are subject to the specific resonance frequency regions. The weighted average current control, which splits the filter capacitor into two parts (in form of an LCCL filter) and commands the current flowing between these two parts, is independent of the resonance frequency, but on the other hand, it is limited by the poor sensitivity to the grid impedance variation and weak stability in the grid current. These limitations are comprehensively explained in this paper and then addressed by identifying that the single-loop weighted average current control is equivalent to the dual-loop grid current control with an inherent capacitor current active damping. By tuning the capacitor split proportion as a second degree of freedom, an optimal damping performance that is robust to the grid impedance variation can be naturally achieved using only the inherent damping. Thus, no extra damping is required, and the single-loop structure with only one current sensing turns to be adequate. Moreover, for convenience of practical implementation, an improved LCCL filter configuration is proposed to allow the use of two equal nominal capacitances for the split capacitors. Finally, experiments are performed to verify the effectiveness of the proposed method.

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<italic>LLCL</italic>-Filtered Grid Converter With Improved Stability and Robustness

Cited by 76 publications

References 30 publications

Passivity-Based Stability Analysis and Damping Injection for Multiparalleled VSCs with LCL Filters

Passivity-Based Stability Analysis and Damping Injection for Multiparalleled VSCs with LCL Filters

Stability Analysis of Current Control based on Virtual Resistor for Single-Phase Grid Converters with LLCL Input Filters

A Highly Robust Single-Loop Current Control Scheme for Grid-Connected Inverter With an Improved LCCL Filter Configuration

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