Line selection method for single-phase earth fault line of small current grounding system

A single-phase ground fault, small current grounding technology, applied to the fault location, fault detection according to the conductor type, etc., can solve the problems of inconvenient installation of signal injection devices, inconsistent sensitivity of line signal detectors, and difficulties in correct line selection. Achieve the effect of optimizing the parameters of the front-end sampling device, easy to change the position, and the method is accurate and reliable

Inactive Publication Date: 2016-11-09
山东博鸿电气股份有限公司
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, the fifth harmonic source in the load, the CT unbalanced current and the size of the transition resistance will all affect the line selection accuracy.
[0013] A serious shortcoming of the fifth harmonic method is that the fifth harmonic content in the fault current only accounts for about 10% of the fundamental wave, and the value will be smaller when the transition resistor is grounded, which is easy to cause misjudgment
If the au

Method used

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  • Line selection method for single-phase earth fault line of small current grounding system
  • Line selection method for single-phase earth fault line of small current grounding system
  • Line selection method for single-phase earth fault line of small current grounding system

Examples

Experimental program
Comparison scheme
Effect test

Example Embodiment

[0045] Example 1:

[0046] Such as figure 1 As shown, multiple cables under the same bus in the low-current grounding mode, by using several high-speed low-current grounding line selection devices, monitor and record the current generated by the fault circuit when a single-phase ground fault occurs in a small-current grounding system. The transient current signal of the ground wire through the metal shielding layer of each loop automatically selects the fault line by identifying the direction of the wave head of the transient current signal.

[0047] Compared with the existing small current fault line selection method, the single-phase grounding fault line selection method of the small current grounding system will effectively improve the accuracy of the small current grounding line selection and avoid multiple selections or missed reports.

[0048] The monitoring and recording method is to use the current sensors of several high-speed and low-current grounding line selection devices...

Example Embodiment

[0055] Example 2:

[0056] On the basis of Embodiment 1, the method of time synchronization is satellite clock synchronization. High-speed and low-current grounding line selection device suitable for multiple wireless connections. In the case of multi-level multiple busbars and multiple outgoing lines, a complex monitoring network is formed. Several wireless devices are connected to a host computer. The data of the same time period or the same time of each high-speed and low-current grounding line selection device is collected by satellite clock synchronization.

Example Embodiment

[0057] Example 3:

[0058] On the basis of Embodiment 1, the satellite clock synchronization method is adopted, and the upper computer compares the received waveform of the faulty line with the waveform of the adjacent normal line, measures the reflected wave, and realizes the fault point ranging.

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Abstract

The invention discloses a line selection method for a single-phase earth fault line of a small current grounding system, and belongs to the electric power cable fault on-line monitoring field. The line selection method comprises a plurality of cables in the same bus with a small current grounding mode, and is characterized in that: transient current signals flowing through each cable outgoing line metal shielding layer grounding line are monitored and recorded through a high speed collection method, the transient current signals are generated by a fault loop when the single-phase grounding fault of the small current grounding system happens; and the fault line is selected by identifying the directions of wave heads of the transient current signals. The method compares the directions of the wave heads of grounding line current traveling waves of all the cables, and distinguishes a fault cable and a non-fault cable. In comparison with other small current grounding line selection methods at present, the accuracy of the line selection is high, and the multi-selection or missing report condition can be effectively avoided.

Description

technical field [0001] The invention belongs to the field of on-line monitoring of power cable faults, in particular to a line selection method for a single-phase ground fault line in a small current grounding system. Background technique [0002] Most of the distribution networks in my country adopt the neutral point not directly grounded system (NUGS), that is, the small current grounding system, which includes the neutral point ungrounded system (NUS) and the neutral point through the arc suppression coil grounding system (NES, also called resonant grounding system). When a fault occurs, since the three line voltages are still symmetrical, especially the NES, the current flowing through the grounding point is very small, which does not affect the continuous power supply to the load, and can still continue to run for 0.5 to 2 hours. However, when the small current grounding system is single-phase grounded, the non-faulty phase voltage will rise to the line voltage, and lon...

Claims

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Application Information

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IPC IPC(8): G01R31/08
CPCG01R31/086
Inventor 魏洪文张立斌厉新波王勃马加庆渠忠磊李玮
Owner 山东博鸿电气股份有限公司
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