Modular multilevel converter with direct-current fault isolation function and submodule thereof

A modular multi-level, DC fault technology, applied in the direction of electrical components, emergency protection circuit devices, etc., can solve the problem of difficult isolation of DC system faults, achieve fault isolation speed and improve the ability to prevent fault re-ignition, and reduce investment costs and switching loss reduction, the effect of reducing the number of

Inactive Publication Date: 2015-05-20
TIANJIN UNIV
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  • Abstract
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  • Claims
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Problems solved by technology

[0005] In order to overcome the problem of difficult isolation of DC system faults in the prior art, the present invention proposes a modular multilevel converter with DC fault isolation capability and its sub-modules. By redesigning the MMC sub-modules, In the event of a DC fault, the reverse polarity of the capacitor voltage in the sub-module is connected to the fault current flow path, thereby realizing the removal of the fault current and fast and effective fault isolation

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  • Modular multilevel converter with direct-current fault isolation function and submodule thereof
  • Modular multilevel converter with direct-current fault isolation function and submodule thereof
  • Modular multilevel converter with direct-current fault isolation function and submodule thereof

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Embodiment Construction

[0014] The technical solution of the present invention will be described in further detail below in conjunction with the accompanying drawings and specific embodiments.

[0015] Such as figure 1 Shown, is the topology structure of the novel MMC converter sub-module, which the present invention calls series double sub-module (series double sub-module, SDSM), consisting of the first to fifth IGBT transistors (T 1 ~T 5 ), the first to sixth diodes (D 1 ~D 6 ), and the first and second capacitors (C 1 ~C 2 )constitute. where the first IGBT transistor T 1 with the first diode D 1 The anti-parallel structure with the second IGBT transistor T 2 with the second diode D 2 The anti-parallel structure is connected in series, and then connected with the first capacitor C 1 parallel to form the first parallel connection; the third IGBT transistor T 3 with the third diode D 3 The anti-parallel structure with the fourth IGBT transistor T 4 with the fourth diode D 4 The anti-par...

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Abstract

The invention discloses a modular multilevel converter with a direct-current fault isolation function and a modular multilevel converter (MMC) submodule. The twin-submodule in series consists of a first to a fifth IGBT (insulated gate bipolar transistor) T1 to T5, a first to a sixth diodes D1 to D6, a first capacitor C1 and a second capacitor C2; the twin-submodule in series includes two operation modes: a normal operation mode and a blocked mode, under the blocked mode, all controllable switches, i.e. the first to the fifth IGBT T1 to T5 are completely switched off, and then the capacitance voltage of the submodule is accessed to a current circulating path in a reverse polarity manner. When a direct-current fault occurs, the submodule enters the blocked mode, and the capacitance voltage is accessed in the reverse polarity manner, so that the elimination of fault current and the fault isolation can be realized. A plurality of twin-modules in series are connected in series to form a bridge arm of the modular multilevel current converter, six bridge arms with the same topology form a three phase full bridge structure and from a modular multilevel current converter structure. The fault isolation speed and the fault recrudescence preventing capacity can be greatly improved, and the investment cost and switch loss are greatly reduced.

Description

technical field [0001] The invention relates to the technical field of power system control, in particular to a novel topology structure of an MMC sub-module with DC fault isolation capability and a fault isolation strategy thereof. Background technique [0002] When a DC fault occurs in the flexible DC system, the fault overcurrent will seriously affect the safe and reliable operation of the entire DC system, including the AC side, DC side and converter. Therefore, when a DC fault occurs, it is required to quickly remove the fault line, that is, a certain fault isolation method must be adopted to isolate the DC fault line. [0003] DC fault isolation is a key technology in the development of flexible DC systems. However, no matter it is a DC system based on a traditional two-level voltage source converter or a DC system based on a traditional modular multilevel converter, when a DC fault occurs, the fault current will quickly rise to a large overcurrent levels and will re...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02H7/10
Inventor 李斌何佳伟
Owner TIANJIN UNIV
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