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A method and device for locating a ground fault point of a DC line

A DC line and grounding fault technology, applied in the direction of the fault location, can solve problems such as failure to locate the fault point, affecting the safe operation of system equipment, and DC system voltage loss.

Inactive Publication Date: 2019-06-11
张烨
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

When the filtering effect of the DC system charger is not good, there will be harmonic components in the DC system, which will seriously affect the correctness of the line selection results
When the system has a large capacitance to ground, the ground branch cannot be found or the ground branch is misjudged
[0005] 3. It cannot be effectively located when there is a single-line multi-point ground fault
[0006] 4. The existing detection method is invalid when the AC and DC are mixed, and the fault point cannot be located
[0007] 5. Various existing detection methods need to change the power supply mode of the DC system, that is, the charger is out of operation and replaced by a battery for power supply
If the distributed capacitance and ground resistance parameters of the DC system meet certain conditions, the withdrawal of the charger will generate large transient overvoltage and overcurrent, which will seriously affect the safe operation of the system equipment, and even cause the DC system to lose voltage.

Method used

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  • A method and device for locating a ground fault point of a DC line

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Embodiment 1

[0035] A device for measuring the ground current of a DC line, characterized in that it includes:

[0036]A current superposition circuit, a first DC leakage current transformer, a second DC leakage current transformer, a subtraction circuit, and a signal conversion module; wherein, the current superposition circuit includes a power supply E, a resistor R connected thereto, and a resistor R1, The resistor R is connected in parallel with the resistor R1; the first DC leakage current transformer detects the current flowing through the branch of the resistor R1 and the line to be tested, and the second DC leakage current transformer detects the current Resistor R1 branch current; the first DC leakage current transformer and the second DC leakage current transformer are respectively electrically connected to the subtraction operation circuit, and the signal transformation module is used to calculate the measured Transform the measured leakage current. The device applies the princ...

Embodiment 2

[0038] A method for locating a ground fault point of a DC line, characterized in that the method comprises:

[0039] Determining the faulty line: Obtain the DC component I of the ground current of the line to be tested by the device provided in Embodiment 1 0 , when the DC component of the ground current I 0 When it is greater than the set value, it is determined that the circuit to be tested is a fault circuit:

[0040] Fault point location: Obtain the DC component I of the ground leakage current at the head end of the fault line 0 , for a DC line that does not form a loop, the DC component of the ground leakage current of the positive or negative single line of the line is equal to the DC component I of the ground leakage current at the head end of the single line (the end connected to the DC bus bar) 0 ; For a DC line forming a loop, the DC component I of the positive and negative single-line leakage current to ground of the line 0 It is equal to synchronous detection of...

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PUM

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Abstract

The invention discloses a DC line ground fault point locating method and device. The device can comprise a current superposition circuit, a first DC leakage current transformer, a second DC leakage current transformer, a subtraction operation circuit and a signal transformation module. The device is simple in structure, convenient to use, high in anti-interference capability and high in precision. A positive electrode (or negative electrode) line which does not form a DC loop can be adaptive to measurement of AC-DC hybrid leakage current. The locating method is high in operability and accurate in fault point locating.

Description

technical field [0001] The invention relates to the technical field of DC line ground fault troubleshooting, in particular to a method and device for locating a DC line ground fault point. Background technique [0002] The DC system of the substation provides reliable DC power for various controls, automatic devices, relay protection, signals, etc., and serves as a working power supply. It also provides reliable operating power for operations. A ground fault in the DC system will cause malfunction or refusal of relay protection, signal, and automatic devices, or cause the DC fuse to blow, causing the protection, automatic devices, and control circuits to lose power, and bring safety hazards to the operation of the power grid, which should be eliminated immediately . In the prior art, the method of locating the faulty circuit and determining the fault point generally adopts the injection detection method. However, the existing detection methods have the following disadvanta...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01R31/08
CPCG01R31/08
Inventor 张烨
Owner 张烨