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Correction type line differential protection method suitable for flexible direct current power transmission system

A power transmission system, flexible DC technology, applied in the direction of automatic disconnection of emergency protection devices, circuit devices, emergency protection circuit devices, etc., can solve problems such as incorrect action and performance degradation

Pending Publication Date: 2022-07-15
CHINA UNIV OF MINING & TECH (BEIJING)
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] Aiming at the problem of performance degradation or even incorrect operation of the existing current differential protection after the flexible DC system is connected, the present invention provides a correction type line differential protection method adapted to the flexible DC transmission system

Method used

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  • Correction type line differential protection method suitable for flexible direct current power transmission system
  • Correction type line differential protection method suitable for flexible direct current power transmission system
  • Correction type line differential protection method suitable for flexible direct current power transmission system

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Embodiment Construction

[0016] The present invention will be further described below in conjunction with the accompanying drawings.

[0017] A correction-type line differential protection method adapted to a flexible direct current transmission system includes the following steps:

[0018] Step 1: As figure 1 and figure 2 , sampling the three-phase current at both ends of the AC line;

[0019] Step 2: As figure 2 , calculate the abnormal data index ADI, if the sampling current exceeds twice the rated current and the abnormal data index ADI is greater than its threshold ADI thr When the abnormal data is identified, step 3 is performed; otherwise, step 4 is performed;

[0020] The specific calculation formula is as follows:

[0021]

[0022]

[0023] In the formula, k rel is the reliability coefficient, take 1.5, N is the number of sampling points in a power frequency cycle, is the initial phase angle. For a power system with a power frequency of 50Hz, when the sampling frequency is 2k...

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Abstract

A topological structure and a control mode of a flexible direct-current power transmission system are remarkably different from a traditional synchronous power supply, so that the fault current characteristic of the flexible direct-current power transmission system is greatly different from that of the synchronous power supply, the current differential protection performance is reduced and even incorrect action is caused, and safe and stable operation of a power system is seriously threatened. The invention discloses a correction type line differential protection method suitable for a flexible direct-current power transmission system, which can still accurately distinguish internal and external faults under the condition that the flexible direct-current power transmission system is connected, and is not influenced by abnormal data and current transformer saturation.

Description

technical field [0001] The invention relates to a correction type line differential protection method adapted to a flexible direct current transmission system, and belongs to the technical field of power system relay protection. Background technique [0002] In the context of the proposal of the "dual carbon" goal and the development of new power systems, flexible DC transmission technology has become a large-scale new energy grid-connected, long-distance and large-capacity technology with its high controllability, high flexibility and high stability. It is a key technology in the fields of power transmission and island power supply, and has broad application prospects. [0003] Different from the traditional synchronous power supply, the fault current of the flexible DC transmission system has a limited amplitude and a controllable phase angle due to the limitation of the overcurrent capability of the fully-controlled power electronic devices and the high controllability of...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02H7/26H02H3/28H02J3/36G01R31/08
CPCH02H7/268H02H3/28H02J3/36G01R31/086
Inventor 梁营玉任昳
Owner CHINA UNIV OF MINING & TECH (BEIJING)