Analysis and Control of Modular Multilevel Converters Under Unbalanced Conditions

Zhou, Yuebin; Jiang, Daozhuo; Guo, Jie; Hu, Pengfei; Liang, Yiqiao

doi:10.1109/tpwrd.2013.2268981

Cited by 135 publications

(52 citation statements)

References 16 publications

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“…balanced input voltages and symmetric arm impedances), assuming that the common-mode current mainly involves the even-order harmonic component and would not affect the differential-mode (output ac) and dc current. MMC operation under unbalanced input ac voltage conditions was analyzed in [24][25][26][27]. It revealed that under such unbalanced conditions, the common-mode current not only contains a dc component and even-order circulating harmonic components, but also includes a second-order zero-sequence harmonic component within the three converter legs, resulting in second-order harmonic components in the dc voltage and current.…”

Section: Introductionmentioning

confidence: 99%

“…It revealed that under such unbalanced conditions, the common-mode current not only contains a dc component and even-order circulating harmonic components, but also includes a second-order zero-sequence harmonic component within the three converter legs, resulting in second-order harmonic components in the dc voltage and current. To eliminate the second-order harmonic oscillations on the dc voltage and current, two methods were proposed: one suppresses the dc voltage ripple [24], and the other directly eliminates the zerosequence harmonic current [25][26][27]. In [27], the possible impact of MMC with asymmetric arm impendence was briefly mentioned and it revealed that the ac current would not split equally between the upper and lower arms, resulting in a fundamental-frequency common-mode current.…”

Section: Introductionmentioning

confidence: 99%

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Analysis and Control of Modular Multilevel Converters under Asymmetric Arm Impedance Conditions

Zeng

Yao

et al. 2016

IEEE Trans. Ind. Electron.

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This version is available at https://strathprints.strath.ac.uk/54225/ 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. IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICSAbstract--This paper presents a detailed analysis and improved control strategy for Modular Multilevel Converters (MMC) under asymmetric arm inductance conditions. Unlike symmetric conditions, the fundamental ac current is not split equally between the upper and lower arms under asymmetric conditions, and the dc and double-frequency components in the common-mode current also flow into the ac side. To solve these issues, a theoretical analysis of the effect of asymmetric conditions on MMC operation is carried out using equivalent circuits at different frequencies. Three control targets are then presented to enhance the operational performance. A control strategy providing the control of differential-mode current, common-mode current and power balance is designed. The feasibility and validity of the proposed analysis and control strategy are demonstrated by simulation results from a threephase MMC system, and simulation and experimental results from a single-phase MMC system. Index Terms--Modular multilevel converter, differential-mode current, common-mode current, power balance, asymmetric conditions. I. INTRODUCTION1 HE modular multilevel converter (MMC) has drawn attention due to its advantages of modular design, high efficiency and scalability, and excellent output waveforms with low harmonic distortion [1][2][3][4][5][6][7][8][9][10].Due to the MMC's unique configuration, there are complex interactions involving different currents and voltages in the MMC, and extensive research has been conducted on the modeling and control strategy of the MMC [11][12][13][14][15][16][17][18][19][20][21][22]. The relationship between the arm current and capacitor voltage was analyzed in [11] and [12]. One of the special characteristics of the MMC is the common-mode current which usuall...

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Analysis and Control of Modular Multilevel Converters under Asymmetric Arm Impedance Conditions

Zeng

Yao

et al. 2016

IEEE Trans. Ind. Electron.

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“…Therefore, several solutions have been explored in the past, by appropriately injecting synthesized currents to attenuate power oscillations. These control strategies include rotating reference frames [86,87] with proportional-integral controllers [85,88], stationary frames [17] with proportional-resonant controllers [16,89], as well as nonlinear hysteresis and predictive deadbeat controllers, among others [90].…”

Section: -Control Methods Under Adverse Ac Conditionsmentioning

confidence: 99%

Enhanced Instantaneous Power Theory for Control of Grid Connected Voltage Sourced Converters Under Unbalanced Conditions

Montanari

Gole

2017

IEEE Trans. Power Electron.

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This thesis introduces a new method especially designed to control the instantaneous power in voltage sourced converters operating under unbalanced conditions, including positive, negative and zero sequence content. A transformation technique, labelled mno transformation, was developed to enable the decomposition of the total instantaneous power flowing on three-phase transmission topologies into constant and oscillating terms. It is applied to three-wire and four-wire schemes, especially accommodating zero sequence unlike previous approaches.

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“…The common internal failures are IGBT short-circuit and open-circuit faults. The fault-tolerant operations of MMCs under external failures have been extensively investigated [5][6][7][8][9][10][11][12], and the IGBT short-circuit fault detection and protection techniques in terms of the internal failures are relatively mature and have been embedded into commercial gate driver boards. Compared to the IGBT short-circuit fault, the IGBT open-circuit fault is not obvious for quick detection and it results in overcurrent, overvoltage, and waveform distortion problems, leading even to the failure of the whole MMC system.…”

Section: Introductionmentioning

confidence: 99%

The Fault Detection, Localization, and Tolerant Operation of Modular Multilevel Converters with an Insulated Gate Bipolar Transistor (IGBT) Open Circuit Fault

Zeng

et al. 2018

Energies

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Reliability is one of the critical issues for a modular multilevel converter (MMC) since it consists of a large number of series-connected power electronics submodules (SMs). In this paper, a complete control strategy including fault detection, localization, and tolerant operation is proposed for the MMC under an insulated gate bipolar transistor (IGBT) open circuit fault. According to the output characteristics of the SM with the open-circuit fault of IGBT, a fault detection method based on the circulating current and output current observation is used. In order to further precisely locate the position of the faulty SM, a fault localization method based on the SM capacitor voltage observation is developed. After the faulty SM is isolated, the continuous operation of the converter is ensured by adopting the fault-tolerant strategy based on the use of redundant modules. To verify the proposed fault detection, fault localization, and fault-tolerant operation strategies, a 900 kVA MMC system under the conditions of an IGBT open circuit is developed in the Matlab/Simulink platform. The capabilities of rapid detection, precise positioning, and fault-tolerant operation of the investigated detection and control algorithms are also demonstrated.

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Analysis and Control of Modular Multilevel Converters Under Unbalanced Conditions

Cited by 135 publications

References 16 publications

Analysis and Control of Modular Multilevel Converters under Asymmetric Arm Impedance Conditions

Analysis and Control of Modular Multilevel Converters under Asymmetric Arm Impedance Conditions

Enhanced Instantaneous Power Theory for Control of Grid Connected Voltage Sourced Converters Under Unbalanced Conditions

The Fault Detection, Localization, and Tolerant Operation of Modular Multilevel Converters with an Insulated Gate Bipolar Transistor (IGBT) Open Circuit Fault

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