Rapid line selection method for single-phase earth fault of low-current grounding system

A single-phase grounding fault, small current grounding technology, applied in the field of power system, can solve the problems of difficulty in selecting wavelet basis, small 5th harmonic, difficulty in raising, etc., achieves low storage space requirements, low requirements, and improves the correct line selection. sexual effect

Active Publication Date: 2021-01-01
国网湖北省电力有限公司黄冈供电公司
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Problems solved by technology

By comparing the 5th harmonic current of the faulty line and the non-faulty line, the 5th harmonic method is proposed, but the 5th harmonic is very small, and it is difficult to propose
The wavele

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  • Rapid line selection method for single-phase earth fault of low-current grounding system
  • Rapid line selection method for single-phase earth fault of low-current grounding system
  • Rapid line selection method for single-phase earth fault of low-current grounding system

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Embodiment Construction

[0029]The present invention will be further described in detail below in conjunction with the drawings and embodiments.

[0030]Such asfigure 2 As shown in the simulation model diagram of a 110kV / 10.5kV low-current grounding system, S is a 110kV power supply. The 10kV bus has 4 10kV feeders, and each carries a certain load. The neutral grounding method of the transformer is changed by controlling the switching of switch k. That is, it is not grounded or grounded through the arc suppression coil. Line 1 is a cable line, line 2 is an overhead line, line 3 is an overhead line, and line 4 is a cable line.

[0031]The fault point is set at f on line 1 1km away from the 10kV bus, and the fault time is 0.102s respectively. In order to verify that the method of the present invention is basically not affected by line length, transition resistance, and arc suppression coil, the following five situations are set:

[0032]Case 1: The length of line 1 is 3km, the length of line 2 is 15km, the length of l...

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Abstract

The invention discloses a rapid line selection method for a single-phase earth fault of a low-current grounding system. The method comprises the steps of firstly collecting the three-phase current instantaneous values at all feeder outlets of a substation in real time; secondly, calculating zero-sequence current instantaneous values of lines according to the current instantaneous values, and solving a second derivative of each zero-sequence current instantaneous value by utilizing an interpolation method; then, finding out the maximum value and minimum value points of the second derivative ofthe instantaneous value of each zero-sequence current instantaneous value of each line within 3ms by taking the fault occurrence moment as a zero moment; and finally, solving the zero-sequence currentchange trend characteristic quantity of each line, and finding out the line with the maximum characteristic quantity, i.e., judging the line as a fault line. The method is slightly influenced by theline length, the transition resistance and an arc suppression coil, and the single-phase earth fault line selection can be rapidly carried out.

Description

Technical field[0001]The invention belongs to the field of electric power systems, and relates to a single-phase grounding fault line selection technology of a power distribution network, in particular to a single-phase grounding fault fast line selection method for a small current grounding system.Background technique[0002]The 10kV distribution network system in my country generally adopts the neutral point indirect grounding method, which includes the neutral point is not grounded, the arc suppression coil is grounded, and the resistance is grounded. In a neutral point indirectly grounded system, when a single-phase grounding fault occurs, the fault point current is very small, so it is also called a small current grounding system. When a single-phase ground fault occurs, the neutral point voltage rises from zero to the phase voltage, and the line voltage between the three phases remains symmetrical and does not affect the normal power supply. Therefore, the system is generally al...

Claims

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Application Information

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IPC IPC(8): G01R31/08G01R31/52G01R31/60
CPCG01R31/086G01R31/088G01R31/52G01R31/60
Inventor 胡秀明张春芬叶傲辉程栋江锋唐亚夫詹清铁宋翔林
Owner 国网湖北省电力有限公司黄冈供电公司
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