System and method for restraining differential bias
US-12149063-B2 · Nov 19, 2024 · US
Method for preventing differential protection maloperation of optical fiber caused by saturation of single CT of 3/2 connection
US10622804B2 · US · B2
| Field | Value |
|---|---|
| Publication number | US-10622804-B2 |
| Application number | US-201615352349-A |
| Country | US |
| Kind code | B2 |
| Filing date | Nov 15, 2016 |
| Priority date | Dec 7, 2015 |
| Publication date | Apr 14, 2020 |
| Grant date | Apr 14, 2020 |
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Abstract
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The present disclosure relates to a method for preventing a maloperation of differential protection of an optical fiber caused by saturation of a single Current Transformer (CT) of 3/2 connection. By applying a combination of the differential judgment and the sub-CT current judgment, reliable identification of internal and external faults is ensured, and the problem of misjudging of the internal fault as the external fault can be prevented as well.
First claim
Opening claim text (preview).
What is claimed is: 1. A method for preventing a maloperation of differential protection of an optical fiber caused by saturation of a single Current Transformer (CT) of 3/2 connection, the method comprising: connecting currents of two switches at a 3/2 connection side to a line protection device respectively, and collecting a sample value of the current 1 between a bus and one of the two switches of a side of a line where the two switches are arranged, a sample value of the current 2 of the side of the line where the two switches are arranged and a sample value of a current of a side of the line opposite to the side where the two switches are arranged during an operation period; when the samples values of the currents at each of three or more successive sampling points satisfy a start condition respectively, judging that a fault occurs, wherein the formula of the start condition is: |iqd k |>1.25|iqd k-2N |+0.4In, where iqd k =|im1 k −im1 k-2N |+|im2 k −im2 k-2N |+|In k −In k-2N |, im1, im2 and in are the sample value of the current 1 between the bus and one of the two switches of the side of the line where the two switches are arranged, the sample value of the current 2 of the side of the line where the two switches are arranged and the sample value of a current of the side of the line opposite to the side where the two switches are arranged, N is a number of samples per cycle, and In is a rated value of the current of the CT; when the samples values of the currents at each of the three or more successive sampling points do not satisfy a differential judgment element and a phase current judgment element respectively after the fault occurs, judging that the fault is an external fault, otherwise, judging that the fault is an internal fault; when it is judged that the fault is the internal fault, opening the differential protection, and when it is judged that the fault is the external fault, locking the differential protection. 2. The method of claim 1 , wherein the formula of the differential judgment element is: { iop k > 0.5 ires k iop k > 0.3 In iop k - iop k - 2 N > 0.2 In , where iop k =im1 k +im2 k +in k |, ires k =|im1 k |+|im2 k |+|in k |, im1, im2 and in are the sample value of the current 1 between the bus and one of the two switches of the side of the line where the two switches are arranged, the sample value of the current 2 of the side of the line where the two switches are arranged and a sample value of a current of the side of the line opposite to the side where the two switches are arranged, N is a number of samples per cycle, and In is a rated value of the current of the CT. 3. The method of claim 1 , wherein the formula of the phase current judgment element is: { im 1 k + im 2 k > 0.5 im 1 k - im 2 k im
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- H02H3/283Primary
and taking into account saturation of current transformers · CPC title
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- What does patent US10622804B2 cover?
- The present disclosure relates to a method for preventing a maloperation of differential protection of an optical fiber caused by saturation of a single Current Transformer (CT) of 3/2 connection. By applying a combination of the differential judgment and the sub-CT current judgment, reliable identification of internal and external faults is ensured, and the problem of misjudging of the interna…
- Who is the assignee on this patent?
- Xj Group Corp, Xj Electric Co Ltd, Xuchang Xj Software Technology, and 1 more
- What technology area does this patent fall under?
- Primary CPC classification H02H3/283. Mapped technology areas include Electricity.
- When was this patent published?
- Publication date Tue Apr 14 2020 00:00:00 GMT+0000 (Coordinated Universal Time) (B2). Legal status and post-grant events are not shown on this page.
- What related patents are in patentsdb?
- We list 8 related publications on this page (citations in our corpus or others sharing the same primary CPC).