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Method and device for finding ground fault in non-injection DC system

A DC system and ground fault technology, applied to fault locations, measuring devices, instruments, etc., can solve the problems of slow search speed, heavy workload, and inability to accurately find the fault point of the ground fault, achieving the effect of reducing running time

Active Publication Date: 2016-06-15
STATE GRID CORP OF CHINA +3
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] However, the current ground fault search generally needs to be completed by experienced maintenance personnel, the search speed is slow, the workload is heavy, and the specific fault point of the ground fault cannot be accurately found
Especially if the ground fault occurs in the thunderstorm season with poor search environment and high risk, it will greatly increase the difficulty of fault search

Method used

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  • Method and device for finding ground fault in non-injection DC system
  • Method and device for finding ground fault in non-injection DC system
  • Method and device for finding ground fault in non-injection DC system

Examples

Experimental program
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Effect test

Embodiment 1

[0051] This embodiment is an embodiment for measuring the insulation resistance of a DC system.

[0052] Reference Figure 4 , The grounding signal generation and control unit measures the voltage to ground of the DC system through the switch K1 and K2, and then calculates the insulation resistance R+ and R- of the positive and negative poles of the DC system according to the measured voltage to ground.

[0053] Reference Figure 5 . The ground signal generation and control unit transforms the DC system bus voltage and ground voltage into a 0~5V low voltage through a resistor divider, and inputs them to the bus voltage measurement unit and the ground voltage measurement unit respectively. The measured value of the ground voltage is used to calculate the positive and negative insulation resistance. The measured value of the bus voltage is used to judge whether the bus voltage of the DC system meets the operating requirements.

[0054] According to the insulation resistance of the po...

Embodiment 2

[0056] This embodiment is an embodiment for measuring the power frequency AC voltage in the DC system's ground voltage.

[0057] Reference Figure 5 , The grounding signal generation and control unit uses capacitors to separate and divide the voltage through resistors to sample the power frequency AC voltage in the DC system bus-to-ground voltage and input it to the bus-to-ground AC voltage measurement unit.

[0058] According to the value of the power frequency AC voltage in the ground voltage of the DC system to the ground, it can be judged whether the DC system has an AC intrusion into the DC system ground fault.

Embodiment 3

[0060] This embodiment is an embodiment for generating a ground signal current.

[0061] Reference Image 6 , The ground signal generation and control unit, through the variable resistance control unit, controls the variable resistance RW, so that the DC system ground voltage V+, V- changes in a sinusoidal manner.

[0062] When the DC system ground voltage V+ and V- change in a sine wave manner, sine wave ground signal currents IR+, IR- will be generated in the positive and negative grounding resistances R+, R-, and the positive and negative ground capacitance C+, C- produces sine wave ground signal current IC+, IC-.

[0063] Among them, the phase of the sine wave ground signal current in the grounding resistance and the sine wave ground signal current in the ground capacitance differ by 90°. The present invention uses this feature to distinguish whether the ground signal current in the feeder branch of the DC system is a resistive current or a capacitive current, thereby avoiding ...

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Abstract

The invention discloses a non-injection type DC system grounding fault finding method and its device. The method includes: connecting a variable resistor to a corresponding position of the system according to the voltage of the positive and negative poles of the DC system to the ground, and then adjusting the variable resistor , so as to generate the ground signal current required by the system; use the clamp current transformer to measure the positive and negative current difference in the DC load feeder, and judge whether there is a ground fault in the DC load feeder according to the measurement results; according to the DC load feeder. Whether there is a sudden change in the positive and negative current difference to find the location of the ground fault point, so as to locate the ground fault of the DC system. The method of the present invention can quickly and accurately find the specific fault points of various ground faults in the DC system, can greatly reduce the running time of the ground fault of the DC power system, reduce the difficulty of finding the ground fault of the DC power system, and reduce the workload of maintenance personnel . The invention can be widely used in the technical field of electric power detection.

Description

Technical field [0001] The invention belongs to the technical field of power detection, and particularly relates to a method and a device for finding a ground fault in a non-injection direct current system. Background technique [0002] DC systems powered by batteries and charging management equipment are widely used in power, communications, railway, chemical and other industries. In order to improve the reliability of power supply, the DC system is set as an ungrounded system, which allows a short-term operation of a ground fault. In order to avoid the malfunction of the protection caused by the two-point grounding, according to relevant regulations, when a ground fault occurs, it must be handled within 24 hours, that is, the grounding fault point must be eliminated to restore the DC system to normal. Therefore, the DC ground fault finding is a daily work of the DC system operation and maintenance personnel. [0003] However, the current ground fault search generally needs to b...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01R31/08G01R31/02
Inventor 任灵陈建鹏胡荣义张霞姚斌赵红艳张小平李春亮徐玉凤
Owner STATE GRID CORP OF CHINA
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