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Starting element for bus current differential protection

A technology for differential protection and start-up components, applied in electrical components, emergency protection circuit devices, etc., can solve problems such as inability to judge CT disconnection and inability to accurately identify CT saturation.

Active Publication Date: 2017-04-26
CHINA ELECTRIC POWER RES INST +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The existing starting criteria for bus differential protection cannot judge CT disconnection, and at the same time, when there is a fault outside the zone, the starting element does not operate, and it is impossible to accurately identify CT saturation

Method used

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  • Starting element for bus current differential protection
  • Starting element for bus current differential protection
  • Starting element for bus current differential protection

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0100] (1) In-area failure

[0101] When a phase B ground fault occurs in the area, the starting action curve of the bus differential current is as follows: Image 6 As shown, the solid line is the fixed value curve, and the dotted solid line is the differential criterion action curve.

[0102] The starting action curve of bus braking current is as follows: Figure 7 As shown, the solid line is the fixed value curve, and the dotted solid line is the braking criterion action curve.

[0103] Other current starting action curves of the busbar are as follows: Figure 8 As shown, the solid line is the fixed value curve, and the dotted solid line is the multi-CT current criterion action curve.

[0104] From the simulation results, it can be seen that for faults in the zone, the braking current start-up criterion, the differential current start-up criterion and the multi-CT current start-up criterion act reliably, and the bus differential start-up element operates.

Embodiment 2

[0106] (2) Out-of-area failure

[0107] When a phase B ground fault outside the zone occurs, the busbar differential start action curve is as follows: Figure 9 As shown, the solid line is the fixed value curve, and the dotted solid line is the differential criterion action curve.

[0108] The bus brake start action curve is as follows: Figure 10 As shown, the solid line is the fixed value curve, and the dotted solid line is the differential criterion action curve.

[0109] Other current starting action curves of the busbar are as follows: Figure 11 As shown, the solid line is the fixed value curve, and the dotted solid line is the differential criterion action curve.

[0110] From the simulation results, it can be seen that when an out-of-area fault occurs, the braking current start-up criterion and other current start-up criteria will act reliably, the differential current start-up element will not act, and the bus differential start-up element will act.

Embodiment 3

[0112] (3) CT disconnection

[0113] In the event of B-phase CT disconnection, the busbar differential start action curve is as follows: Figure 12 As shown, the solid line is the fixed value curve, and the dotted solid line is the differential criterion action curve.

[0114] The bus brake start action curve is as follows: Figure 13 As shown, the solid line is the fixed value curve, and the dotted solid line is the differential criterion action curve.

[0115] Other current starting action curves of the busbar are as follows: Figure 14 As shown, the solid line is the fixed value curve, and the dotted solid line is the differential criterion action curve.

[0116] It can be seen from the simulation results that when the CT disconnection occurs, the differential current start criterion and the brake current start criterion act, but the multi-CT current start criterion does not act, and the bus differential start element does not act.

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Abstract

The invention relates to a starting element for bus current differential protection, comprising: a differential current starting relay, a brake current starting relay and a plurality of CT current starting relays. The differential current starting relay and the brake current starting relay are in OR gate output. The OR gate output is in AND gate output with the plurality of CT current starting relays. The bus protection starting element proposed by the invention is realized through the use of the sampled value of the three-phase current mutation at one time without performing half-wave or full-wave Fourier transform changes, which eliminates the influence of the cross-window operation on the starting element sensitivity. With the starting element, it is possible to accurately identify the time when faults occur both inside and outside a bus area and to accurately identify the CT broken lines of the bus and faults.

Description

Technical field: [0001] The invention relates to the field of relay protection of electric power systems, and more particularly relates to a starting element for bus current differential protection. Background technique: [0002] The starting element is an important part of bus differential protection, and its sensitivity directly affects the action speed of bus differential protection and CT saturation identification. The domestic busbar protection adopts phase current sudden change start element or steady state current start element, and "or" logic is adopted between the two. The existing starting criteria for bus differential protection cannot judge CT disconnection, and at the same time, when there is a fault outside the zone, the starting element does not operate, and CT saturation cannot be accurately identified. Invention content: [0003] The purpose of the present invention is to provide a starting element for busbar current differential protection, which can acc...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02H7/22
CPCH02H7/226
Inventor 王兴国柳焕章周泽昕杜丁香郭雅蓉
Owner CHINA ELECTRIC POWER RES INST
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