Semi-wave DC detection method

A technology for direct current, detection methods, applied in the direction of measuring current/voltage, measuring device, measuring electrical variables, etc.

Active Publication Date: 2011-04-13
JINING POWER SUPPLY CO OF STATE GRID SHANDONG ELECTRIC POWER CO +2
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0008] The purpose of the present invention is to solve the defects of the traditional DC current detection method, provide a simple and practical method to detect the injected DC current, and realize the advantages of single-phase ground fault line selection and positioning of distribution network based on the DC injection method. Detection method of wave direct current

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment

[0089] (1) Theoretical calculation

[0090] It is known that in formula (7), N=1200, μ r = 1000, d = 10m, r 0 =5mm, ω=2πf, f=50Hz, then I dc When changing, the corresponding induced electromotive force e can be obtained, and the calculation results are shown in the following table.

[0091] Lead wire

Flow I dc

(mA)

100

200

300

400

500

600

700

800

900

1000

1500

2000

induction electric

Potential E(mV)

0.06

0.12

0.18

0.24

0.30

0.36

0.42

0.48

0.54

0.6

0.90

1.2

[0092] (2) Actual distribution network model simulation

[0093] Taking a substation of an oil production plant as a model for simulation, the neutral point of the grounding substation is connected to a DC generator, and the calculated 100Hz signal is obtained when the transition resistance i...

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Abstract

The invention discloses a method for detecting semiwave direct current, which overcomes the defects of the conventional direct current detection method and has the advantages of simplicity, convenience, practicability and the like. The method comprises that: 1) when a power distribution system has a singlephase earth fault, the neutral voltage of a grounding transformer is set to be sinusoidal signals with the power frequency of 50Hz; 2) a direct current generator is subjected to siliconstack half wave rectification to generate direct current, the direct current is semiwave direct current which is also called pulsating direct current and is injected to the fault power distribution system, and direct current signals are wire selecting and positioning judgment signals to be detected; and 3)according to the electromagnetic field principle, the semiwave direct current generates a magnetic field, so the semiwave direct current can be detected by detecting the magnetic field generated by the semiwave direct current.

Description

Technical field: [0001] The invention relates to a DC current detection method in the line selection and location technology for single-phase ground faults in distribution networks, in particular to a detection method for half-wave DC currents. diagnostic signal. Background technique: [0002] The neutral point operation mode of my country's distribution network adopts the neutral point ungrounded mode or the arc suppression coil grounded mode. After a single-phase ground fault occurs, no short-circuit loop is formed, and only a small zero-sequence current caused by the distributed capacitance of the system makes the Distribution network single-phase ground fault line and location is a technical problem that has not been completely resolved. The DC injection method is a very effective single-phase ground fault line selection and location principle. When a single-phase ground fault occurs, a half-wave DC current is injected from the neutral point of the primary side of the gr...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01R31/08G01R19/00
Inventor 刘伟生张慧芬田质广张恩平孔平王彦良邵立新肖云东孙旭那徐万田王红
Owner JINING POWER SUPPLY CO OF STATE GRID SHANDONG ELECTRIC POWER CO
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