Study of the MMC circulating current for optimal operation mode in HVDC applications

Marchesoni, M.; Vaccaro, Luis

doi:10.1109/epe.2015.7311781

Cited by 9 publications

(5 citation statements)

References 2 publications

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“…In [10] the authors present an investigation into the potential of future SiC JFET switching devices to improve the efficiency of MMC converters. Some works have looked at modifying the circulating current flowing within the MMC in order to reduce losses by taking advantage of the superior conduction characteristics of the anti-parallel diodes within each IGBT module [11], [12]. Other research effort has also been placed into SM balancing techniques that allow for reduced switching losses within the converter, whilst also achieving low deviation in capacitor voltages [13]- [15].…”

Section: Introductionmentioning

confidence: 99%

Thyristor/Diode-Bypassed Submodule Power Groups for Improved Efficiency in Modular Multilevel Converters

Judge

Merlin

Green

et al. 2019

IEEE Trans. Power Delivery

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The half-bridge Modular Multilevel Converter (MMC) is a Voltage Source Converter (VSC) with high efficiency, controllability and modularity. The topology is weak to DC side faults unless bipolar sub-modules are used, but this results in decreased efficiency. Power-Groups (PGs), a thyristor augmented multilevel structure, have been proposed as a way to reduce the power-loss increase arising from achieving DCfault-tolerance. This paper investigates whether the PG concept can also achieve significant efficiency improvements in VSCs that are not required to be DC fault tolerant. A Single Sub-Module Voltage (SSMV) method of controlling the turn-on/turn-off of the thyristor assembly within each PG structure is presented and the differences with the previously detailed Dual Sub-Module Voltage (DSMV) technique are described. Two thyristor-based PG structures for use in non-DC-fault-tolerant MMCs are proposed, one using SSMV and the other using DSMV. A comparison is made considering the required semiconductor device count, the impact on thyristor snubber design, and the overall powerlosses achieved. A further, simplified, variant using a diode bypassed PG structure is presented which results in powerloss reductions during rectifier mode only. Results show that power-loss reductions of ∼20-25% can be achieved by using the proposed PG structures to augment a half-bridge MMC.

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Section: Introductionmentioning

confidence: 99%

Thyristor/Diode-Bypassed Submodule Power Groups for Improved Efficiency in Modular Multilevel Converters

Judge

Merlin

Green

et al. 2019

IEEE Trans. Power Delivery

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“…Regardless of this deviation, it is experimentally verified that the total cell losses can be reduced with respect to zero circulating current, with a great reduction of the energy ripple. This reduction in both objectives with respect to case A for φ = 0°has been reported in [37,38], while the always negative effect of the second harmonic on the losses for φ = 90°is observed in [39]. Regarding the energy ripple model, the voltage drop of the semiconductors is an important source of error in low-voltage MMCs, which is not taken into account by the model.…”

Section: Implementation and Experimental Resultsmentioning

confidence: 93%

Pareto Frontier of the Arm Energy Ripple and the Conduction Losses of a Modular Multilevel Converter

López¹,

Fehr²,

Pérez³

et al. 2021

Energies

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Modular multilevel converters can achieve high power quality and voltage ratings, becoming a good alternative for high-voltage direct-current applications. However, the circulating current and capacitor voltage ripple remain significant drawbacks, mainly due to the impact on efficiency and power density. In this work, a stationary operation of a modular multilevel converter is optimized by calculating the Pareto frontier of the arm energy ripple and the conduction losses for different operating conditions. From the set of optimal solutions, the best trade-off between energy ripple and power losses can be chosen depending on the application requirements. Therefore, an optimal operating point regarding capacitor voltage ripple and circulating current was found, optimizing efficiency and allowing a reduction of capacitance, hence size and cost. The theoretical analysis and results are validated experimentally on a prototype test-bench.

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“…However, no experimental results related to such a type of converter are known in the technical literature. On the contrary, the MMC concept attracts the attention in high-power and high-voltage applications [40,62,63,[77][78][79]: electrical drives [80], HVDC [81][82][83][84][85], photovoltaic [86] and in stationary installations that supply the primary lines of German railways (i.e., from 110 kV-50 Hz three-phase to 110 kV-16.7 Hz single-phase).…”

Section: Conceptmentioning

confidence: 99%

Energy Efficiency in Electric Motors, Drives, Power Converters and Related Systems

Marchesoni¹

2020

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Study of the MMC circulating current for optimal operation mode in HVDC applications

Abstract: An exhaustive study on the circulati HVDC applications is presented. Th minimize the capacitors voltage ripp

Cited by 9 publications

References 2 publications

Thyristor/Diode-Bypassed Submodule Power Groups for Improved Efficiency in Modular Multilevel Converters

Thyristor/Diode-Bypassed Submodule Power Groups for Improved Efficiency in Modular Multilevel Converters

Pareto Frontier of the Arm Energy Ripple and the Conduction Losses of a Modular Multilevel Converter

Energy Efficiency in Electric Motors, Drives, Power Converters and Related Systems

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