Flexible DC short-circuit fault protection method based on thyristor chain and superconducting current limiter

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 issues, to achieve the effect of fault current isolation, fast response speed of current limiting, and avoid capacity limitation

CN113036724BActive Publication Date: 2022-07-05SOUTHEAST UNIV
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Patents(China)
Current Assignee / Owner
Publication Date
2022-07-05

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Abstract

The invention discloses a flexible DC short-circuit fault protection method based on a thyristor chain and a superconducting current limiter. The converter used in the flexible DC power transmission system is a modular multi-level converter based on cascaded half-bridge sub-modules: ABC three-phase structure, each phase includes an upper bridge arm and a lower bridge arm, each bridge arm is composed of several half-bridge sub-modules and a bridge arm inductor; the output port of the modular multi-level converter AC side is connected in parallel with a thyristor A superconducting current limiter is connected in series with each of the three-phase lines on the AC side of the modular multilevel converter; the upper ends of the three-phase upper arms of the modular multilevel converter are short-circuited and connected to the DC side through the first mechanical switch , the lower end of the three-phase lower bridge arm is short-circuited and then connected to the DC side through the second mechanical switch. The protection method realizes the current isolation of the AC and DC sides under fault conditions by opening the thyristor chain and reduces the fault current of the DC side to zero, and limits the fault current of the AC side through the superconducting current limiter, thereby realizing the DC short-circuit fault protection of the flexible DC transmission system.
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Description

technical field

[0001] The invention belongs to the technical field of multi-level 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] Modular Multilevel Converter (MMC) is composed of multiple sub-modules with the same structure cascaded, and the voltage and power levels can be changed by adjusting the number of cascaded sub-modules, and any level of power can be realized. output, thereby effectively reducing the harmonic components of the output voltage and reducing the switching frequency and loss of the power switching device. With its high efficiency, easy expansion, easy redundancy design and many other advantages, MMC has shown its important engineering application prospects in high-voltage and high-power systems, and is gradually being applied to grid-connected renewable energy, motor drives, and rail transit. and ...

Examples

Embodiment Construction

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

[0031] like figure 1 As shown in the figure, the converter used in the flexible DC transmission system based on thyristor chain and superconducting current limiter is a modular multi-level converter based on the cascade of half-bridge sub-modules, specifically an ABC three-phase structure. It includes an upper bridge arm 1.1 and a lower bridge arm 1.2, each bridge arm is composed of several half-bridge submodules (SM) 1.3 and a bridge...