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: 2009-08-12
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

Method used

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Examples

Experimental program
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Example Embodiment

[0091] Example

[0092] (1) Theoretical calculation

[0093] Knowing (7) where, 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 as follows.

[0094] Wire in the power

[0095] (2) Simulation of actual distribution network model

[0096] Using a substation of an oil production plant as a model for simulation, a DC generator is connected to the neutral point of the grounding transformer, and the calculated 100Hz signal is obtained when the transition resistance is different.

[0097] ①At the time of metallic ground fault

[0098] The detection of half-wave DC current on the faulty line is as follows: Figure 7a When it is a metallic ground fault, the half-wave DC current on the fault line, Figure 7b In the case of a metallic ground fault, the induced potential of a coil of 1200 turns around a magnet rod at a distance of 10m; Figure 7c When it is ...

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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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IPC IPC(8): G01R31/08G01R19/00
Inventor 张慧芬高志鹏田质广张恩平朱秀香桑在中
Owner JINING POWER SUPPLY CO OF STATE GRID SHANDONG ELECTRIC POWER CO
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