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Method for discriminating tail current in ineffective protection based on DC component blocking

A failure protection and DC component technology, which is applied in the direction of measuring current/voltage, measuring electrical variables, measuring devices, etc., can solve the problems that the circuit breaker failure protection current criterion cannot be returned quickly, the fault range expands, and tailing, etc., to achieve reduction Distinguish the time of failure tailing current, accelerate the phase-separated locking failure protection, and achieve good results in safe and stable operation

Active Publication Date: 2016-09-07
NARI TECH CO LTD +4
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  • Abstract
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AI Technical Summary

Problems solved by technology

However, when a fault occurs in the system, the relay protection device issues a trip command, and the circuit breaker is disconnected to remove a fault, there is still an attenuating current on the secondary side of the electromagnetic current transformer, that is, CT (Current Transformer, current transformer) tailing Phenomenon
CT trailing current may cause the current criterion of circuit breaker failure protection to fail to return quickly, and the failure protection may malfunction after reaching the delay time, thereby expanding the fault range and causing serious consequences such as large-scale power outages
At present, there are not many methods for judging the current tailing of failure protection, and the criterion that the tailing current does not exceed zero is generally used. However, after the tailing current passes through the CT of the protection device, the phenomenon of current zero crossing may occur, and its applicability is not strong.

Method used

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  • Method for discriminating tail current in ineffective protection based on DC component blocking
  • Method for discriminating tail current in ineffective protection based on DC component blocking
  • Method for discriminating tail current in ineffective protection based on DC component blocking

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Embodiment Construction

[0022] The present invention will be further described below in conjunction with the accompanying drawings. The following examples are only used to illustrate the technical solution of the present invention more clearly, but not to limit the protection scope of the present invention.

[0023] Such as figure 1 As shown in , a current tailing discrimination method for failure protection based on DC component blocking includes the following steps:

[0024] Step 1, define the maximum number of branches as M.

[0025] Step 2, define X=1.

[0026] Step 3, read the failure switch input of the Xth branch.

[0027] Step 4, calculating the failure current condition;

[0028] Step 5: Calculate the fundamental RMS value I of the phase current fundamental wave of the previous cycle of the Xth branch.

[0029] Step 6, if In , then go to step 7, if I≥NI n , then the failure trailing current discrimination starts, go to step 8; among them, I n is the rated current, and N is the multipl...

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Abstract

The invention discloses a method for discriminating ineffective protection tail current based on DC component blocking. The method uses proportion of DC component in a phase current to determine an ineffective tail current. The method is easy to operate, has high efficiency, greatly reduces the time of a replay protection apparatus in discriminating the ineffective tail current, and effectively increases accuracy in discriminating the ineffective tail current. The method makes it possible that when a fault current occurs, the ineffective protection does not refuse initiation, and when a CT tail current occurs, the ineffective protection is not wrongfully initiated, and the method accelerates phase-splitting and ineffective protection, prevents enlargement of an accident, and provides better safeguard for safe and stable operation of a power grid.

Description

technical field [0001] The invention relates to a method for judging the tailing of a failure protection current based on DC component blocking, and belongs to the field of relay protection of electric power systems. Background technique [0002] The relay protection device is an inseparable part of the power system, and it is the most basic, important and effective technical means to ensure the safety of power equipment and prevent and limit large-scale power outages in the power system. However, when a fault occurs in the system, the relay protection device issues a trip command, and the circuit breaker is disconnected to remove a fault, there is still an attenuating current on the secondary side of the electromagnetic current transformer, that is, CT (Current Transformer, current transformer) tailing Phenomenon. CT tailing current may cause the current criterion of circuit breaker failure protection to fail to return quickly, and the failure protection may malfunction af...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01R19/00
CPCG01R19/00
Inventor 戴魏白亮亮王寅丞郑玉平潘书燕吴崇昊邹志杨
Owner NARI TECH CO LTD
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