Flexible direct-current short-circuit fault protection method based on thyristor chain and superconducting current limiters

A technology of superconducting current limiter and flexible direct current, applied in emergency protection circuit devices for limiting overcurrent/overvoltage, usage of superconductor elements, emergency protection circuit devices, etc., can solve the problem of uncontrolled rectification path and high cost , increase and other problems, to achieve the effect of fault current isolation, fast response speed of current limit, and avoid capacity limitation

CN113036724AActive Publication Date: 2021-06-25SOUTHEAST UNIV
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Patent Information

Authority / Receiving Office
CN · China
Current Assignee / Owner
Publication Date
2021-06-25

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Abstract

The invention discloses a flexible direct-current short-circuit fault protection method based on a thyristor chain and superconducting current limiters. A converter used in a flexible direct-current power transmission system is a modularized multi-level converter cascaded based on half-bridge sub-modules and is of an A-B-C three-phase structure, and each phase comprises an upper bridge arm and a lower bridge arm; each bridge arm consists of a plurality of half-bridge sub-modules and a bridge arm inductor; an alternating current side output port of the modular multilevel converter is connected in parallel with the thyristor chain; the three-phase lines of the AC side of the modular multilevel converter are each connected in series with a superconducting current limiter; the upper ends of the three-phase upper bridge arms of the modular multilevel converter are connected to a direct current side through a first mechanical switch after being short-circuited, and the lower ends of the three-phase lower bridge arms are connected to the direct current side through a second mechanical switch after being short-circuited. According to the protection method, alternating-current and direct-current side current isolation under a fault condition is achieved by turning on the thyristor chain, the direct-current side fault current is reduced to zero, the alternating-current side fault current is limited through the superconducting current limiters, and therefore direct-current short-circuit fault protection of the flexible direct-current power transmission system is achieved.
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Description

technical field

[0001] The invention belongs to the technical field of multilevel power electronic converters, and in particular relates to a flexible DC short-circuit fault protection method based on a thyristor chain and a superconducting current limiter. Background technique

[0002] The Modular Multilevel Converter (MMC) is composed of multiple sub-modules with the same structure cascaded. By adjusting the number of cascaded sub-modules, the voltage and power level can be changed, and any level of power can be realized. output, thereby effectively reducing the harmonic component of the output voltage, reducing the switching frequency and loss of the power switching device. MMC, with its high efficiency, easy expansion, easy redundancy design and many other advantages, has shown its important engineering application prospects in high-voltage and high-power systems, and is gradually being applied to renewable energy grid-connected, motor drives, and rail transit. and othe...

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Embodiment Construction

[0030] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

[0031] like figure 1 As shown, the converter used in the flexible direct current transmission system based on thyristor chains and superconducting current limiters is a modular multilevel converter based on cascaded half-bridge sub-modules, specifically ABC three-phase structure, each phase Contains an upper bridge arm 1.1 and a lower bridge arm 1.2, each bridge arm is composed of several half-bridge submodules (submodule, SM) 1.3 and a bridge arm inductor 1.4; the...