DC circuit breaker based on serial-in capacitor and DC fault handling strategy thereof

A technology of DC circuit breakers and capacitors, applied in the field of DC circuit breakers and their DC fault handling strategies, can solve the problems of large size, high cost, and difficult power grids to be widely used, and achieve low steady-state operation losses, lower investment costs, and reduced The effect of investment cost

CN107749615AActive Publication Date: 2018-03-02ZHEJIANG UNIV
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Patent Information

Authority / Receiving Office
CN · China
Current Assignee / Owner
Publication Date
2018-03-02

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Abstract

The invention discloses a DC circuit breaker based on a serial-in capacitor and a DC fault handling strategy thereof. The DC circuit breaker includes a normal through-current branch, a main transfer branch, a cut-off branch, a reactor, and a disconnecting switch. The normal through-current branch is composed of an ultra-fast mechanical switch and a load transfer switch connected in series. The main transfer branch is composed of a main circuit breaker. The cut-off branch is composed of a thyristor valve group and a centralized capacitor connected in series. The load transfer switch is composedof a plurality of sub modules with bidirectional through-current capacity in series-parallel connection. The main circuit breaker can be composed of a plurality of reduced half-bridge sub modules inseries-parallel connection. The nature of a fault current is changed by using a capacitor, and thus, the fault current can be blocked. Moreover, fewer IGBTs are used, and the engineering cost and theoperation loss can be greatly reduced. The DC circuit breaker based on a serial-in capacitor and the DC fault handling strategy thereof have strong reference significance and application value in engineering.
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Description

technical field

[0001] The invention belongs to the technical field of power electronic systems, and in particular relates to a DC circuit breaker based on a capacitor connected in series and a DC fault processing strategy thereof. Background technique

[0002] There are two basic network construction methods for DC power grids: the first network construction method uses a modular multilevel converter (MMC) plus DC circuit breaker scheme based on half-bridge sub-modules. This network construction method is suitable for any number of terminals. The second network construction method uses MMC with DC fault self-clearing capability, such as the MMC based on the full bridge sub-module, but does not require DC circuit breakers. This network construction method is suitable for small-scale networks with less than 10 terminals DC grid. When the half-bridge sub-module MMC plus DC circuit breaker is used to construct the network, the converter station is usually required to continue ...

Examples

Embodiment Construction

[0024] In order to describe the present invention more specifically, the technical solutions of the present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0025] Such as figure 1 As shown, the DC circuit breaker of the present invention based on capacitors in series includes a normal flow branch, a main transfer branch, a cutoff branch, a reactor and a disconnector, wherein: the normal flow branch, the main transfer branch and the breaker The three flow branches are connected in parallel, one end of the parallel connection is connected to the DC line, and the other end is connected to one end of the isolating switch; the other end of the isolating switch is connected to one end of the reactor; the other end of the reactor is connected to the converter station.

[0026] The normal flow branch includes an ultra-fast mechanical switch and a load transfer switch, where the ultra-fast mechanical switch and load ...