New submodule circuits for modular multilevel current source converters with DC fault ride through capability

Yu, Xinyu; Wei, Yingdong; Jiang, Qinglin

doi:10.1109/apec.2016.7468062

Cited by 17 publications

(10 citation statements)

References 17 publications

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“…For completeness of the review, this section includes VSC-based SMs that have been developed for other applications. The DBSMs of Figure 12a,b are designed as HB-SM alternatives for current-source converters [76], while the Packed U-Cell SM (7L-PUC [77]) uses hybrid voltage levels and unequal device ratings in a structure mostly suitable, but with many design and operation limitations, to ac-ac conversion. These three SMs will also not be further considered for the loss analysis in the rest of this article.…”

Section: Csc and Ac-ac Submodulesmentioning

confidence: 99%

Review, Classification and Loss Comparison of Modular Multilevel Converter Submodules for HVDC Applications

Tian

Wickramasinghe

et al. 2022

Energies

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The circuit topology of a submodule (SM) in an modular multilevel converter (MMC) defines many of the functionalities of the complete power electronics conversion system and the specific applications that a specific MMC configuration can support. Most prominent among all applications for the MMC is its use in high-voltage direct current (HVDC) transmission systems and multiterminal dc grids. The aim of the paper is to provide a comprehensive review and classification of the many different SM circuit topologies that have been proposed for the MMC up to date. Using an 800-MVA, point-to-point MMC-based HVDC transmission system as a benchmark, the presented analysis identifies the limitations and drawbacks of certain SM configurations that limit their broader adoption as MMC SMs. A hybrid model of an MMC arm and appropriate implementations of voltage-balancing algorithms are used for detailed loss comparison of all SMs and to quantify differences among multiple SMs. The review also provides a comprehensive benchmark among all SM configurations, broad recommendations for the benefits and limitations of different SM topologies which can be further expanded based on the requirements of a specific application, and identifies future opportunities.

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Section: Csc and Ac-ac Submodulesmentioning

confidence: 99%

Review, Classification and Loss Comparison of Modular Multilevel Converter Submodules for HVDC Applications

Tian

Wickramasinghe

et al. 2022

Energies

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“…The third valve type identified is the three-quadrant valve, which is capable of generating voltages in the first three quadrants during switched operation, and in the first and third quadrant when blocked. Generating voltages in the third quadrant during switched operation relies upon semi-blocked SM states, where a portion of the insulated-gate bipolar transistors (IGBTs) within each SM are blocked, while the remaining IGBTs remain actively gated [60,61]. Examples of SMs which can be used to wholly or partially form this valve type are the sparse full-bridge ( Fig.…”

Section: Converter and Sm Topologymentioning

confidence: 99%

“…Converters with this type of valve are capable of controlling their DC-side currents during a DC-side fault. They can at the same time also partially control their AC-side currents, but this inherently results in rectified DC current [61,62].…”

Section: Converter and Sub-module Topologymentioning

confidence: 99%

“…Consequently, active fault current level control in rectifying mode and active recharge of the DC network from zero DC voltage can be achieved. STAT-COM mode operation may also be achieved by mapping the AC currents in an upwards direction through each valve, as discussed in [61,62]. This control mode, however, results in a DC current also being injected into the faulted DC network.…”

Section: Type IVmentioning

confidence: 99%

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Power‐system level classification of voltage‐source HVDC converter stations based upon DC fault handling capabilities

Judge

Chaffey

Wang

et al. 2019

IET Renewable Power Generation

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To date, numerous concepts for converter station designs for use in voltage source converter (VSC)-based highvoltage direct current (HVDC) systems have been proposed. These differ not only in converter circuit topology, sub-module design, and control scheme but also in AC-or-DC switchgear and other auxiliary equipment. In the main, the existing literature categorises these converter stations according to just the converter circuit technologies and controls. However, for the development of network codes and to enable systematic network studies, a system-focused and technology-independent classification is needed. As such a classification does not yet exist, this study proposes a new framework, which categorises VSC station designs according to their capabilities during a DC-side fault and the method by which post-fault restoration may be achieved, given that these are the main differentiating factors from a system perspective. The classification comprises six converter station types and three time-intervals through which to fully characterise a design. Many well-known forms of converters are used as case studies, and simulation results are used to exemplify the classification framework. The outcome is a generic and technology-independent way of characterising converter station designs that is useful in wider power-system analysis but also for putting proposed converter stations into context.

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“…However, retaining the rated dc current even at zero active power causes high transmission losses. In addition, the rated dc current at low dc voltages changes and increases the arm energy fluctuations [19,20], thereby increasing the capacitance requirement.…”

Section: Introductionmentioning

confidence: 99%

An Operating Mode Based on Variable DC Voltage and Current for Enlarging P–Q Capability Range of Unidirectional Current H-Bridge Submodule-Based MMC

Song

et al. 2022

IEEE Access

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Modular multilevel converters (MMCs) are widely utilized in dc applications. With the development of MMCs, many applications require the MMCs to have additional functions and characteristics, such as dc fault clearing capability and low submodule capacitance. A unidirectional current H-bridge submodule (UCH-SM) has been proposed, which uses low submodule capacitance and possesses dc fault clearing capability. However, the reactive power capability is limited during low active power because of the inadequate dc bias in arm currents caused by the low dc current. Although retaining a rated dc current even at zero active power has been proposed, it results in increasing the power losses and large capacitance. This study proposes a new operating mode based on variable dc voltage and variable dc current (VVVCM) for point-to-point dc systems. The basic idea is that both the dc voltage and current vary on the basis of active power and a lower limit is set for the dc current to provide adequate dc bias in the arm currents during reactive power exchange. Analysis shows that the UCH-MMC in VVVCM has an enlarged P-Q capability range and still retains low capacitor usage. Simulation results verify the effectiveness of the proposed mode.INDEX TERMS UCH-MMC, variable dc voltage and current mode, P-Q capability range, compactness

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New submodule circuits for modular multilevel current source converters with DC fault ride through capability

Cited by 17 publications

References 17 publications

Review, Classification and Loss Comparison of Modular Multilevel Converter Submodules for HVDC Applications

Review, Classification and Loss Comparison of Modular Multilevel Converter Submodules for HVDC Applications

Power‐system level classification of voltage‐source HVDC converter stations based upon DC fault handling capabilities

An Operating Mode Based on Variable DC Voltage and Current for Enlarging P–Q Capability Range of Unidirectional Current H-Bridge Submodule-Based MMC

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