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A method and system for transient protection of multi-terminal hybrid high-voltage DC lines

A high-voltage DC and transient protection technology, applied in emergency protection circuit devices, information technology support systems, power transmission AC networks, etc. The effect of internal and external fault identification

Active Publication Date: 2021-01-19
SOUTH CHINA UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, too high transition resistance will seriously weaken the characteristics of traveling waves, making it difficult to distinguish faults inside and outside the zone, resulting in protection refusal
Therefore, the insufficient ability to withstand transition resistance has always been a problem that needs to be solved in the DC line traveling wave / transient protection
However, this approach involves the cooperation between at least four measuring point information, the logic is complex and affects the quickness of the protection

Method used

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  • A method and system for transient protection of multi-terminal hybrid high-voltage DC lines
  • A method and system for transient protection of multi-terminal hybrid high-voltage DC lines
  • A method and system for transient protection of multi-terminal hybrid high-voltage DC lines

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Embodiment 1

[0065] A multi-terminal hybrid HVDC line transient protection method based on the multi-terminal hybrid HVDC transmission system such as figure 1 shown. figure 1 A typical multi-terminal hybrid HVDC system is shown with fault points closely related to HVDC line protection (only the positive line is shown due to bipolar symmetry). Among them, the LCC station is used as a rectifier station, and the two MMC stations are used as inverter stations. figure 1 Among them, the smoothing reactor and the current limiting reactor are used as the boundary elements between the converter station and the line; f1, f2 and f3 are the fault points at the first, middle and end of the DC line AB respectively; f4, f5 and f6 are the DC The fault points at the beginning, middle and end of line BC; f7, f8 and f9 are the fault points outside the valve side of the boundary element. Generally, protection measuring point 1 is installed at the exit of the rectifier station to detect DC faults and start t...

Embodiment 2

[0162] This embodiment provides a multi-terminal hybrid high-voltage DC line transient protection system, the system includes:

[0163] The component calculation module uses the protection measuring point to measure the pole line voltage and pole line current, and calculates the line mode voltage traveling wave and the ground mode voltage traveling wave;

[0164] The starting unit is used for preliminary judgment, and starts protection when the criterion is met;

[0165] The fault direction identification unit is used to identify forward faults and reverse out-of-area faults; if it is a forward fault, fault pole selection is performed, otherwise the protection does not operate;

[0166] The fault pole selection unit is used to judge whether the fault is the fault of the local pole or the fault of the opposite pole; if it is a fault of the local pole, it will carry out fault identification and fault line location in the area, otherwise the protection of the local pole will not ...

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Abstract

The invention belongs to the field of high-voltage direct-current line protection and relates to a transient protection method for a multi-terminal hybrid high-voltage direct-current line. The methodcomprises the following steps: measuring polar line voltage and polar line current by using a protection measuring point, and calculating line mode and ground mode voltage traveling waves; performingpreliminary judgment, and starting protection when criteria are met; identifying a forward fault and a reverse external fault; if the fault is the forward fault, carrying out fault pole selection, otherwise, not performing protection; in the fault pole selection unit, judging whether the fault is a local pole fault or an opposite pole fault; if the fault is the local pole fault, carrying out internal fault identification and fault line positioning, otherwise, not allowing local pole protection to act; and identifying an internal fault and an external fault by using the time domain transient voltage ratio, positioning a fault line, and carrying out corresponding protection action. The invention further provides a transient protection system for the multi-terminal hybrid high-voltage direct-current line. According to the invention, the problems of insufficient fault line positioning and transition resistance tolerance capabilities of the multi-terminal hybrid high-voltage direct-currentline are solved.

Description

technical field [0001] The invention belongs to the field of high-voltage direct current line protection, and relates to a multi-terminal hybrid high-voltage direct current line transient protection method and system. Background technique [0002] With the rapid development of power electronics technology, multi-terminal HVDC transmission technology has attracted widespread attention. Because the grid commutated converter (Line Commutated Converter, LCC) has the advantages of large transmission capacity and low cost, it has been widely used in the traditional two-terminal direct current transmission system. However, for the multi-point DC transmission system, the LCC inverter station has the risk of commutation failure. Compared with LCC, Modular Multilevel Converter (MMC) has the advantages of flexible control and modular design. However, in order to obtain the same transmission capacity as LCC, MMC requires higher construction costs. In order to meet the above challenge...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02H7/26H02J3/36G01R31/08
CPCG01R31/085H02H7/265H02H7/268H02J3/36Y02E60/60Y04S10/52
Inventor 陈鑫全李海锋许灿雄梁远升王钢
Owner SOUTH CHINA UNIV OF TECH
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