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Intelligent leakage protector provided with broken null line protection function and broken null line protection method

A technology of leakage protector and protection function, which is applied in the field of intelligent leakage protector and its broken zero line protection, can solve the problem of no major breakthrough in zero-break protection, achieve the goal of eliminating faults, obvious social benefits, and avoiding the weakness of high-quality service Effect

Inactive Publication Date: 2014-11-19
STATE GRID CORP OF CHINA +2
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

At present, the protection of the protector has been greatly improved in terms of communication, voltage and current protection, but only the zero-off protection has not made a major breakthrough. So far, this problem has not been effectively solved.

Method used

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  • Intelligent leakage protector provided with broken null line protection function and broken null line protection method
  • Intelligent leakage protector provided with broken null line protection function and broken null line protection method
  • Intelligent leakage protector provided with broken null line protection function and broken null line protection method

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Embodiment 1

[0030] refer to figure 1 , the intelligent leakage protector with broken zero line protection function of the present invention mainly includes: a high-precision zero-sequence current transformer (CT) connected to the secondary winding of the three-phase AC power line (including a magnetic coil of a leakage inductor) ), collect the three-phase unbalanced current I on the three-phase AC power line path or ; In the case of the normal operation of the post-stage load, according to the electromagnetic principle, the magnetic flux passing through the zero-sequence CT magnetic coil (that is, its leakage inductor) is Φ=μHS, and the single-phase load has an L line and an N line each , the current I flowing in this inductor coil 1 and the outgoing current I 2 The resulting alternating magnetic field strength H 1 and H 2 It should be satisfied that the magnetic field strength H in the coil is:

[0031] H = ...

Embodiment 2

[0040] On the basis of the foregoing embodiments, the zero-sequence CT further includes three phase-splitting single-CT components separately provided for each phase load, and is used to separately collect the AC signal of each phase.

[0041] Further, the phase A induced current I of the phase A sampling CT component, the B phase sampling CT component and the C phase sampling CT component of the three-phase power line are respectively sampled A , Phase B induced current I B and C-phase induced current I C signal, respectively, with the neutral current I n By comparison, three logical signal values ​​are obtained, and then the three logical values ​​are coupled by the controller 10 to obtain corresponding logical actions.

Embodiment 3

[0043] On the basis of the foregoing embodiments, a method for protecting a broken neutral line of a three-phase AC power line is designed, which includes:

[0044] 1) Collect the three-phase unbalanced current I on the three-phase AC power line path through a zero-sequence CT or ;

[0045] 2) determine the three-phase unbalanced current I by the first logic circuit or whether a first threshold is exceeded;

[0046] 3) Collect the neutral line current I on the three-phase AC power line path through a zero-break detection CT n ;

[0047] 4) Determine the neutral line current I through the second logic circuit n whether a second threshold is exceeded;

[0048] 5) Determine the three-phase unbalanced current I or is greater than the first threshold and this neutral current I n Whether it is less than the second threshold value, so as to determine whether a fault of a broken neutral line occurs.

[0049] In one embodiment, step 2) further includes: judging by the control c...

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Abstract

The invention discloses an intelligent leakage protector provided with broken null line protection function. The intelligent leakage protector comprises a high-precision zero sequence CT, a first logic circuit, a high-precision broken null line detection CT, a second logic circuit, and a control circuit, wherein the high-precision zero sequence CT is connected onto a three-phase AC electric power line passage, and is used for collecting three-phase out-of-balance current Ior; the first logic circuit is connected with the zero sequence CT, and sends out a first logic signal when the three-phase out-of-balance current Ior surpasses a first threshold value; the high-precision broken null line detection CT is used for collecting natural current In; the second logic circuit is connected with the broken null line detection CT, and sends out a second logic signal when the natural current In surpasses a second threshold value; the control circuit acquires the first logic signal or the second logic signal, confirms that a return circuit broken null line breakdown occurs and generates a warning signal when the three-phase out-of-balance current Ior is greater than the first threshold value and the natural current In is smaller than the second threshold value. The intelligent leakage protector can accurately diagnose a broken null line breakdown and sends out a tripping command to conduct error correction and prognosis interrupt processing on signal processing.

Description

technical field [0001] The invention relates to power system load distribution technology, more specifically, the invention relates to an intelligent leakage protector with a broken neutral line protection function and a broken neutral line protection method in a three-phase four-wire system. Background technique [0002] In the low-voltage power supply system, the disconnection of the neutral line of the distribution network is a frequent problem. In this field, two protection methods, "TT" or "TN-C", are usually used. The normal load of the neutral line can guarantee the three-phase AC voltage. stability and symmetry. The neutral line or neutral line can ensure that the three-phase load voltage is equal to the phase voltage of the power supply, and is not affected by the nature of the load itself. If any phase power line in the three-phase four-wire system is disconnected, only the phase voltage load will be affected. , will not affect the rest of the hatchback voltage. ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02H3/32H02H3/04
Inventor 邹永龙蒋建杰卢峰周安仁谢华跃苏毅方陈蕾庄晓丹
Owner STATE GRID CORP OF CHINA
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