An Improved Control System for Modular Multilevel Converters with New Modulation Strategy and Voltage Balancing Control

Fan, Shengfang; Zhang, Kai; Xiong, Jian; Xue, Yaosuo

doi:10.1109/tpel.2014.2304969

Cited by 177 publications

(104 citation statements)

References 25 publications

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“…The goal is to achieve an equal power distribution among the SMs. In general, it is possible to separate voltage balancing methods in distributed and centralized methods [26].…”

Section: Capacitor Voltage Balancingmentioning

confidence: 99%

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Thermal Analysis and Balancing for Modular Multilevel Converters in HVDC Applications

Hahn

Andresen

Buticchi

et al. 2018

IEEE Trans. Power Electron.

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Abstract-The modular multilevel converter (MMC) has become a very attractive solution for interfacing high voltages in hybrid networks. The MMC enables scalability to different power levels, full controllability provided by IGBTs and can achieve very high efficiencies by using a low switching frequency method as the nearest level modulation. However, the nearest level modulation requires a capacitor voltage balancing algorithm, which can result in unbalanced loading for the power semiconductors in the different submodules. Particularly at low power factor operation, which could occur in case of low-voltage ride through and of reactive power injection, the conventional algorithm is not effective anymore. This article provides thermal stress analysis of the MMC in operation and proposes a thermal balancing approach, which is embedded in the capacitor voltage balancing algorithm. The purpose of the thermal balancing is to achieve similar stress distribution among the different submodules to enhance the lifetime. The junction temperatures in the different submodules are studied for HVDC applications and the article proves experimentally, that the thermal balance within the submodules is significantly improved.

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“…The goal is to achieve an equal power distribution among the SMs. In general, it is possible to separate voltage balancing methods in distributed and centralized methods [26].…”

Section: Capacitor Voltage Balancingmentioning

confidence: 99%

“…The balancing control causes a modification in the modulating signals and requires a sufficiently high switching frequency [26]. However, the hardware and software costs for controllers would become excessive in an HVDC application due to the huge number of SMs.…”

Section: Capacitor Voltage Balancingmentioning

confidence: 99%

Thermal Analysis and Balancing for Modular Multilevel Converters in HVDC Applications

Hahn

Andresen

Buticchi

et al. 2018

IEEE Trans. Power Electron.

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“…Usually the problem of capacitor voltage balancing relate to balancing capacitor voltages within one arm, which is achieved by exploiting modulation methods and tightly related to the switching frequency [1], [11]- [13]. In addition, balancing controllers are also used to maintain the energy stored in the converter phases or in the entire converter while the modulation methods ensure the correct energy distribution within chainlinks [7], [14], [15]. Arm balancing mechanisms reported in literature are used to compensate for the converter asymmetries and transient imbalance.…”

Section: Introductionmentioning

confidence: 99%

“…Often, the modulation signal for each cell is derived to provide balancing within the arm and also amongst arms [9], [16], [17]. In other methods arm balancing is achieved by manipulating the circulating current reference to control the absorbed arm powers [7], [15], [18].…”

Section: Introductionmentioning

confidence: 99%

Arm-Balancing Control and Experimental Validation of a Grid-Connected MMC With Pulsed DC Load

Jankovic

Costabeber

Watson

et al. 2017

IEEE Trans. Ind. Electron.

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Abstract-This paper focuses on the operation of a grid connected Modular Multilevel Converter (MMC) supplying a pulsed DC load. The goal is to achieve minimum AC power fluctuation despite the high power fluctuation present on the DC side. The MMC has been selected for its inherent ability to decouple AC and DC current controllers. However, if no additional provisions are taken, the pulsed load causes imbalance of cell capacitor voltages between upper and lower arm in each phase. The paper presents the theoretical analysis of the imbalance problem, and proposes a simple arm balancing controller to enable the operation of the converter under pulsed DC load. The effectiveness of the controller has been successfully verified on a 7 kW MMC experimental prototype with a 3 kA pulsed DC load.

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“…The voltagebalancing of the SM capacitors within the same arm with an acceptable voltage ripple is another serious concern for the operation of such a converter. This issue has been widely investigated in recent literature [15][16][17][18][19][20][21]; however, voltage and current sensors are always required to achieve voltage-balancing. Recent HVDC applications based on the MMC have involved the use of hundreds of SMs per phase [3].…”

mentioning

confidence: 99%

Capacitor Voltage Estimation Scheme With Reduced Number of Sensors for Modular Multilevel Converters

Abushafa¹,

Gadoue

Dahidah

et al. 2018

IEEE J. Emerg. Sel. Topics Power Electron.

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An Improved Control System for Modular Multilevel Converters with New Modulation Strategy and Voltage Balancing Control

Cited by 177 publications

References 25 publications

Thermal Analysis and Balancing for Modular Multilevel Converters in HVDC Applications

Thermal Analysis and Balancing for Modular Multilevel Converters in HVDC Applications

Arm-Balancing Control and Experimental Validation of a Grid-Connected MMC With Pulsed DC Load

Capacitor Voltage Estimation Scheme With Reduced Number of Sensors for Modular Multilevel Converters

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