Control of a grid connected modular multilevel converter under pulsed DC load

Jankovic, Marija; Costabeber, Alessandro; Watson, Alan J.; Clare, Jon

doi:10.1109/iecon.2015.7392482

Cited by 3 publications

(15 citation statements)

References 7 publications

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“…However, it can be shown that the presence of 50 Hz ripple in the DC voltage is a constant source of imbalance between converter arms. If not compensated, this causes increased low frequency AC power fluctuation and AC current distortion [7], [10]. This makes arm balancing controllers necessary to achieve low AC power fluctuation.…”

Section: Introductionmentioning

confidence: 99%

“…Jankovic During operation, the klystron modulators draw from the DC link input capacitor high current 140 µs long pulses at a repetition rate of 50 Hz. As a result, the DC voltage will have a 50 Hz ripple component [7]. Consequently, a defined amount of DC power fluctuation is present [4] and the converter should act as a firewall, limiting the AC power fluctuation below 2 % (for specifications refer to [4]).…”

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%

“…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%

“…Since the pulsed load is a constant source of imbalance among converter arms, the arm balancing controller has to be capable of achieving zero error in the steady state, which is typically guaranteed by PI based controllers, such as those used in [7], [15], [19].…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

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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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

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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Per-Phase Controller for Medium Voltage Full-Bridge Modular Multilevel Converters

Noori¹,

Costabeber²,

Sumner³

et al. 2017

IET International Conference on Resilience of Transmission and Distribution Networks (RTDN 2017)

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This work proposes a per-phase control architecture for a fullbridge modular multilevel converter (FB-MMC) intended for medium voltage applications, such as MVDC multi-terminal distribution networks in off-shore wind farms or MVDC networks in industrial plants. The converter under study operates with 20kV on the DC side and is connected to an 11kV AC grid through a ∆-Y transformer. The response to a single line to ground (SLG) AC fault of the converter controlled with the proposed per-phase control architecture is compared with the conventional MMC using dq control. Simulation results in Matlab-Plecs prove that the proposed control approach has better response to a SLG fault compared with the conventional one, while maintaining a simple structure.

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Control of a modular multilevel converter with pulsed DC load

Jankovic

Watson

Costabeber

et al. 2016

2016 IEEE Energy Conversion Congress and Exposition (ECCE)

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Abstract-This paper focuses on a Modular Multilevel Converter grid interface for a klystron modulator system that behaves as a pulsed DC load. With such a load, and without mitigating control, the MMC suffers from cell capacitor voltage imbalance between the converter arms which leads to distortion (fluctuation) of the absorbed AC power. This paper proposes an augmented modulation strategy, with a tailored distribution of the modulation signals between the arms within a phase, to ensure low AC power fluctuation. The effectiveness of the method has been verified through simulation and has been experimentally proven on a 7 kW MMC prototype operating with a 3 kA pulsed DC load.

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Control of a grid connected modular multilevel converter under pulsed DC load

Cited by 3 publications

References 7 publications

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

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

Per-Phase Controller for Medium Voltage Full-Bridge Modular Multilevel Converters

Control of a modular multilevel converter with pulsed DC load

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