Hybrid modular multilevel converter based multi‐terminal DC/DC converter with minimised full‐bridge submodules ratio considering DC fault isolation

Suo, Zhiwen; Li, Gengyin; Xu, Lie; Li, Rui; Wang, Weisheng; Chi, Yongning

doi:10.1049/iet-rpg.2016.0281

Cited by 15 publications

(6 citation statements)

References 27 publications

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“…They therefore offer DC fault blocking and active control of DC fault currents. The mixed cell modular multilevel converter (MC-MMC) is an example of an MMC that employs asymmetric bipolar cells [10], [11], [13], [20], [21]. Moreover, the use of symmetrical bipolar cells such as the full-bridge or five-level cross connected cells lead to MMCs that can operate with bipolar (positive and negative) DC voltage, including zero voltage, and can reverse the DC or active power by change of DC current or voltage polarities.…”

Section: Introductionmentioning

confidence: 99%

“…Most of the hybrid converters developed in the last decade were motivated by the tradeoffs between DC fault ride-through, efficiency and footprint. Amongst the many hybrid converter topologies proposed in the open literature in recent years, the MC-MMC is the most attractive topology as it retains many of the attributes of the conventional MMC such as modularity and simple methods for bypassing faulted cells, while permitting delivery of customized features such as bespoke control range for a given level of semiconductor losses [20].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Enhanced Modular Multilevel Converter With Reduced Number of Cells and Harmonic Content

Vozikis

Adam

Rault

et al. 2020

IEEE J. Emerg. Sel. Topics Power Electron.

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This paper presents an alternative implementation of a modular multilevel converter (MMC) that generates a large number of voltage levels per phase with high resolution voltage steps from a reduced number of cells per arm. The presented MMC employs a half-bridge chain-link of medium-voltage cells and a full-bridge chain-link of low-voltage cells in each of its arms. The total blocking voltage of the full-bridge chain-link is equivalent to half that of the medium-voltage half-bridge cell. The use of half and full-bridge cells with two distinct rated voltages in each arm permits full exploitation of the full-bridge cells to generate high resolution multilevel voltage waveforms with fine stepped transitions between major voltage steps of the medium-voltage half-bridge cells. In this manner, errors in the synthesis of the common-mode voltages of the three phase legs due to switching of the cell capacitors in and out the power path are reduced. The nested multilevel operation of the proposed MMC results in a number of voltage levels which is related to the product, rather than the sum, of the numbers of half and full-bridge cells. Detailed comparisons with existing MMC implementations show that the proposed MMC implementation offers the best design trade-offs (superior AC and DC waveforms with reduced control and power circuit complexity). The validity of the proposed MMC implementation is confirmed using simulations and experimentally.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Enhanced Modular Multilevel Converter With Reduced Number of Cells and Harmonic Content

Vozikis

Adam

Rault

et al. 2020

IEEE J. Emerg. Sel. Topics Power Electron.

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“…One is the fast detection and isolation technology of DC faults [6,7]. The second is the DC voltage transformation technology [8,9]. The third is the power flow control technology of the DC lines [10,11].…”

Section: Introductionmentioning

confidence: 99%

A Local Protection and Local Action Strategy of DC Grid Fault Protection

Zhang

2020

Energies

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Fast detection and isolation of direct current (DC) faults are key issues for DC grids. Therefore, it is very necessary to study the fault protection principle for DC grids. This paper firstly presents the main difficulties in DC fault protection. Then, a local protection and local action strategy for isolating the DC faults is proposed. To illustrate the performance of the proposed protection strategy, a four-terminal DC grid with the hybrid high voltage direct current (HVDC) circuit breakers (HVDC CBs) is constructed in the time-domain simulation software PSCAD/EMTDC as the test system. The systematical comparison between the ordinary protection strategy and the proposed strategy is carried out. The protection selectivity of the proposed local detection and local action strategy is thoroughly studied through complete DC line fault scanning of the test system. The simulation results show that the proposed strategy is of high protection selectivity and speed. In addition, the current rating and the voltage of HVDC CB could be greatly reduced with the proposed strategy, which proves the economic benefits of the proposed strategy.

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“…H IGH-POWER dc-dc converters play an important role enabling the emergent dc grid proposition to have many applications such as electric railways [1], [2], HVDC systems [3], [4], renewable generation [5], [6], all-electric ships [7], dc multi-terminal interconnection [8] and others all of which require a medium or high voltage dc interface. The use of dc offers some advantages over traditional ac links such as the lower conduction losses, the asynchronous operation, the higher active power transfer capability and the absence of low-frequency reactive energy circulation.…”

Section: Introductionmentioning

confidence: 99%

Current-Fed Multipulse Rectifier Approach for Unidirectional HVDC and MVDC Applications

Lambert

Soares

Wheeler

et al. 2019

IEEE Trans. Power Electron.

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Abstract-Even though multipulse rectifiers are a long established and well-known technology, still their behavior is not fully described in the literature when they are fed by three-phase balanced sinusoidal currents sources. To address the aforementioned gap, this work presents the operation and properties of current-fed multipulse rectifiers. The undertaken aim is achieved by analyzing the examined topology through circuit analysis and then, the theoretical results are validated through comparisons with the simulated waveforms and experimental results. Furthermore, the expected harmonic content and the duality with traditional voltage-fed multipulse rectifiers are presented. In the proposed structure, the transformer voltages present a multipulse waveform, instead of its primary currents as in voltage-fed multipulse rectifiers. This implies on limiting the voltage steps and its derivative which might be beneficial to reduce cost and volume of insulation, particularly for MVDC and HVDC applications. Besides that, by actively controlling the primary currents, a possible copper loss reduction is shown in the transformer windings, differentiating the proposed structure from its voltage controlled counterpart.

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Hybrid modular multilevel converter based multi‐terminal DC/DC converter with minimised full‐bridge submodules ratio considering DC fault isolation

Cited by 15 publications

References 27 publications

Enhanced Modular Multilevel Converter With Reduced Number of Cells and Harmonic Content

Enhanced Modular Multilevel Converter With Reduced Number of Cells and Harmonic Content

A Local Protection and Local Action Strategy of DC Grid Fault Protection

Current-Fed Multipulse Rectifier Approach for Unidirectional HVDC and MVDC Applications

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