CT broken line rapid locking method and system based on braking current and zero sequence current

A technology of fast blocking and braking current, applied in the direction of electrical components, emergency protection circuit devices, etc., to solve the effect of loop shunt and three-phase impedance imbalance

Pending Publication Date: 2022-03-29
NARI TECH CO LTD +6
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0006] In order to solve the deficiencies in the prior art, the present invention provides a fast blocking method and system for CT disconnection based on braking current and ...

Method used

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  • CT broken line rapid locking method and system based on braking current and zero sequence current

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Embodiment 1

[0020] A fast blocking method for CT disconnection based on braking current and zero-sequence current, including: obtaining the current sampling value of each branch of the bus; calculating the large difference braking current value according to the current sampling value of each branch of the bus; calculating the floating threshold value; compare the current large-difference braking current value with the floating threshold value, and output the first comparison result; obtain the zero-sequence mutation value of each branch of the bus except the contact branch; The maximum value of the zero-sequence mutation value is output as the first calculation value; calculate the sum of the absolute values ​​of the zero-sequence mutation values ​​of the busbar branches except the contact branch, as the second calculation value; compare the second calculation value value and K times the first calculation value, and output the second comparison result; the first comparison result and the s...

Embodiment 2

[0046] Based on the fast blocking method for CT disconnection based on braking current and zero-sequence current described in Embodiment 1, this embodiment provides a fast blocking system for CT disconnection based on braking current and zero-sequence current, including:

[0047] The first data acquisition module is used to acquire the current sampling value of each branch of the bus;

[0048] The first data processing module is used to calculate the large difference braking current value according to the current sampling value of each branch of the bus;

[0049] The second data processing module is used to calculate the floating threshold;

[0050] The first comparison module is used to compare the current large difference braking current value with the floating threshold value, and output the first comparison result;

[0051] The second data acquisition module is used to acquire the zero-sequence mutation value of each branch of the bus bar except the contact branch;

[00...

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Abstract

The invention discloses a CT disconnection quick locking method and system based on braking current and zero sequence current in the technical field of bus differential protection. The method comprises the steps that current sampling values of all branches of a bus are obtained; the large-difference braking current value and the floating threshold value are compared, and a first comparison result is output; comparing the sum of K times of the maximum value of the zero-sequence break variable value of each branch of the bus and the absolute value of the zero-sequence break variable value of each branch, and outputting a second comparison result; according to a preset criterion, it is judged that bus single-phase CT disconnection occurs, and bus differential protection of the phase is locked; the problem of bus differential protection misoperation locking when the braking current CT disconnection criterion has an intra-region single-phase high-resistance fault under the condition of partial heavy load, a metallic fault outside a bus region, a homonymous phase high-resistance fault in the bus region and the like is solved; and meanwhile, the problem of misoperation locking bus differential protection under the conditions of loop shunt, three-phase impedance imbalance and the like of the zero sequence current CT disconnection criterion in a three-second wiring mode is solved.

Description

technical field [0001] The invention belongs to the technical field of busbar differential protection, and in particular relates to a fast blocking method and system for CT disconnection based on braking current and zero-sequence current. Background technique [0002] The bus differential protection relies on the current transformer (CT) and its secondary circuit to complete the analog quantity acquisition. If the current transformer is disconnected due to an abnormality in the secondary circuit, a differential current will be generated in the bus protection, which will easily lead to misoperation of the bus protection. Mistaken tripping of the busbar will cause power failure in the whole station, seriously threatening the stability of the power system. [0003] Both CT disconnection and internal fault will generate differential current, and the protection must judge whether it is CT disconnection or internal fault in a relatively short time. The current CT disconnection cr...

Claims

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Application Information

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IPC IPC(8): H02H7/22H02H7/26
CPCH02H7/226H02H7/262
Inventor 王寅丞戴魏刘丹王业吴通华郑玉平朱翔张凯宇王鹤鸣常鑫瑞
Owner NARI TECH CO LTD
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