A thermal shock suppression control method for mmc single-phase AC ground fault based on active bypass

A ground fault, single-phase AC technology, applied in the direction of output power conversion devices, electrical components, etc., can solve the problems of device damage, uneven heat distribution, device operation, etc., achieve cost reduction, improve reliability, and extend device life Effect

Active Publication Date: 2019-09-06
ZHEJIANG UNIV
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  • Abstract
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Problems solved by technology

Uneven heat distribution and frequent thermal swings will cause the device to work outside the safe operating area, which are the two main factors leading to device damage

Method used

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  • A thermal shock suppression control method for mmc single-phase AC ground fault based on active bypass
  • A thermal shock suppression control method for mmc single-phase AC ground fault based on active bypass
  • A thermal shock suppression control method for mmc single-phase AC ground fault based on active bypass

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Embodiment Construction

[0042] In order to describe the present invention in more detail, the technical solution of the present invention will be described in detail below with reference to the drawings and specific embodiments.

[0043] The MMC single-phase AC ground fault thermal shock suppression control strategy based on the active bypass of the present invention is applicable to the MMC-HVDC system, in which the MMC is connected to a three-phase AC power grid (A, B, C) and a high voltage DC power grid (P, N) It is a key device for realizing AC and DC power conversion. In this embodiment, it is assumed that the MMC adopts the nearest level approximation modulation NLM.

[0044] The basic unit of MMC in this embodiment is the submodule SM, such as figure 1 As shown, N sub-modules SM are cascaded in series with a bridge arm inductor to form a bridge arm of the MMC, and two upper and lower bridge arms are connected in series to form a phase unit. The three-phase MMC converter contains three phase units,...

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Abstract

The invention discloses an active bypass-based MMC single-phase AC grounding fault thermal shock suppression control method. By implementing a midpoint shift control strategy and an active bypass control strategy for the MMC, the converter station can be unblocked. , effectively solve the problem of uneven heat distribution of MMC devices, provide reactive power and active power support for AC and DC power grids, improve the reliability and stability of MMC and its devices, and improve the AC fault ride-through capability. The midpoint displacement control strategy of the present invention solves the problem of uneven heat distribution among the three phases in the MMC, and generates newly added redundant submodules in each phase; the active bypass control strategy utilizes newly added redundant submodules to implement Bypass rotation can effectively solve the problem of uneven heat distribution of different sub-modules in the same bridge arm; at the same time, the invention uses bidirectional thyristor bypass sub-modules with strong overcurrent capability to avoid the IGBT and its anti-parallel diodes under the MMC sub-module from passing through for a long time High current and overheating damage.

Description

Technical field [0001] The invention belongs to the technical field of power electronics, and specifically relates to an active bypass-based MMC single-phase AC grounding fault thermal shock suppression control method. Background technique [0002] Modular Multilevel Converter (MMC) has obvious advantages in medium and high voltage applications because of its low harmonic content, high transmission efficiency, high degree of modularity, and easy expansion. At present, MMC, as a commutation device at the sending end and receiving end of electric energy, has been widely used in High Voltage Direct Current (HVDC) systems. [0003] With the increase of the capacity of the MMC-HVDC system, when the system fails, the scope is wider, and the damage caused by the failure becomes more serious. Therefore, the system has higher and higher performance requirements for MMC. MMC not only has to withstand the disturbance of the faulty grid, but also can provide sufficient support for the DC or A...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02M1/32
CPCH02M1/32H02M1/327
Inventor 李武华杨贺雅董玉斐刘永霞何湘宁
Owner ZHEJIANG UNIV
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