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A method for judging the nature of short-circuit faults in flexible DC power grids and a reclosing method

A short-circuit fault and flexible DC technology, which is applied in short-circuit testing, circuit devices, emergency protection circuit devices, etc., can solve problems such as secondary hazards of the power grid, and achieve the effects of improving safety, facilitating preset value setting, and simplifying design

Active Publication Date: 2021-02-09
HUAZHONG UNIV OF SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] The present invention provides a method for judging the nature of a short-circuit fault in a flexible DC power grid and a reclosing method, which are used to solve the problem that in the restart method of the existing flexible DC power grid, it is easy to judge the nature of the line fault by reclosing after the de-ionization of the line is completed. Technical Problems of Power Grid Bringing Secondary Hazards

Method used

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  • A method for judging the nature of short-circuit faults in flexible DC power grids and a reclosing method
  • A method for judging the nature of short-circuit faults in flexible DC power grids and a reclosing method
  • A method for judging the nature of short-circuit faults in flexible DC power grids and a reclosing method

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Effect test

Embodiment 1

[0038] A method 100 for identifying the nature of a short-circuit fault in a flexible DC power grid, such as figure 1 shown, including:

[0039]When a short-circuit fault occurs on a DC transmission line in the flexible DC grid and both DC circuit breakers on the transmission line are disconnected, the active converter controlling the input side of the transmission line generates an AC detection signal and passes the DC at the input end. The commutation branch of the circuit breaker is injected into the transmission line;

[0040] The fault characteristic quantity is detected on the transmission line, and based on different fault characteristics corresponding to different fault characteristic quantity responses, the detected fault characteristic quantity is compared with the preset value to determine the nature of the short-circuit fault, and complete the discrimination of the short-circuit fault nature of the flexible DC grid.

[0041] It should be noted that this method can...

Embodiment 2

[0065] A method for reclosing a flexible DC power grid, comprising:

[0066] Based on the nature of the short-circuit fault obtained by a method for discriminating the nature of the short-circuit fault of the flexible DC power grid as described in the first embodiment above, if the nature of the short-circuit fault is a permanent fault, then control all the DC circuit breakers to enter the locked state; if the nature of the short-circuit fault is If there is a transient fault, all the DC circuit breakers are controlled to reclose.

[0067] Aiming at the secondary opening problem that circuit breaker reclosing may face when a permanent fault occurs in the current overhead flexible DC grid, the present invention introduces a flexible DC grid reclosing method based on active MMC signal injection. After a DC fault occurs and the DC circuit breaker is disconnected, switch the DC current control mode of the DC circuit breaker to generate an AC active signal, which is injected into t...

Embodiment 3

[0070] A storage medium, where instructions are stored, and when the computer reads the instructions, an enable signal is output to enable the computer to perform the above-mentioned identification of the nature of a short-circuit fault of a flexible DC power grid as described in the first embodiment above method and a flexible DC power grid reclosing method as described in the second embodiment above.

[0071] The relevant technical solutions are the same as those in Embodiment 1 and Embodiment 2, and will not be repeated here.

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Abstract

The invention discloses a flexible direct-current power grid short-circuit fault property judging method and a reclosing method. The judging method comprises the following steps that: when a short-circuit fault occurs on a direct-current power transmission line in a flexible direct-current power grid, and two direct-current circuit breakers of the line are switched off, the input-side active converter of the line is controlled to generate alternating-current signals, and the alternating-current signals are injected into the line through the commutation branch of the input-end direct-current circuit breaker; and the fault characteristic quantity of the line is detected, the detected fault characteristic quantity is compared with a preset value on the basis that different fault properties are corresponding to different fault characteristic quantities, and therefore, the property of the fault can be judged. According to the flexible direct-current power grid short-circuit fault property judging method and the reclosing method of the invention, after the direct-current short-circuit fault occurs and the direct-current circuit breakers are switched off, the active converter is controlled to generate the alternating-current signals used for identifying the property of the direct-current short-circuit fault; the alternating-current signals are injected into the fault line through thecommutation branch of the direct-current circuit breaker; the property of the fault can be judged on the basis that different responses are generated according to different faults; and therefore, thedirect-current circuit breaker is prevented from reclosing under a permanent fault, and the recovery speed of a power grid of which the instantaneous fault has been removed is accelerated.

Description

technical field [0001] The invention belongs to the field of flexible direct current transmission, and more specifically relates to a method for judging the nature of a short-circuit fault in a flexible direct current grid and a reclosing method. Background technique [0002] The flexible direct current transmission system based on the modular multilevel converter (MMC) has the advantages of easy expansion, small line loss, fast and flexible control, etc. be widely used. The DC power grid can flexibly allocate power between various converter stations, and when a converter station exits due to a failure, the remaining systems can still be kept in operation; considering the cost of long-distance and large-capacity transmission, flexible direct transmission The system often uses overhead lines for large-scale power transmission. Therefore, the overhead flexible DC power grid is an inevitable trend in the development of DC transmission technology in the future. Since overhead ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02H7/26H02H3/06G01R31/52G01R31/58
CPCH02H3/066H02H7/268
Inventor 文劲宇蔡普成向往周猛
Owner HUAZHONG UNIV OF SCI & TECH
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