Eureka AIR delivers breakthrough ideas for toughest innovation challenges, trusted by R&D personnel around the world.

Electric leakage protection method and system for mining variable-frequency driving system

A technology of leakage protection and variable frequency drive, which is applied in the direction of automatic disconnection emergency protection devices, emergency protection circuit devices, electrical components, etc., can solve the problems of loss of hierarchical protection, lower sensitivity, and mutual influence, so as to improve safety and improve Effects on Safety and Reliability

Active Publication Date: 2020-12-18
TAIYUAN INST OF CHINA COAL TECH & ENG GROUP +1
View PDF6 Cites 2 Cited by
  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0002] With the promotion and use of frequency conversion drive systems in coal mines, especially on airborne equipment, coal shearers, continuous miners, shuttle cars, and bolters mostly use frequency conversion traction systems. Due to the traditional leakage protection system, there must be a grounding resistance. , resulting in only one set of leakage protection at the back end of the entire transformer. If there are multiple sets, they will inevitably affect each other and cannot work normally.
That is, at the back end of the transformer, all electrical equipment share a set of leakage protection, and the insulation status of other electrical equipment is completely dependent on it, which loses the meaning of hierarchical protection. If the insulation to the ground is low, it is difficult to accurately locate point of failure
For the AC power supply system, the current conventional detection principle in coal mines is zero-sequence voltage current and additional DC method. For standard power frequency electrical equipment, its performance can be fully satisfied, but for variable frequency drive devices, due to the existence of high frequency leakage current, Its zero-sequence voltage and current detection method does not work properly
The additional DC detection method can be barely used, but for the high-power four-quadrant variable frequency drive device, which often malfunctions, it can only be barely used by reducing the sensitivity.

Method used

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
View more

Image

Smart Image Click on the blue labels to locate them in the text.
Viewing Examples
Smart Image
  • Electric leakage protection method and system for mining variable-frequency driving system
  • Electric leakage protection method and system for mining variable-frequency driving system
  • Electric leakage protection method and system for mining variable-frequency driving system

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0031] Such as figure 1 As shown, the embodiment of the present invention provides a mine-used variable frequency drive system leakage protection method, including the following steps:

[0032] S1. High-speed sampling: four-way synchronous sampling is performed on the three-phase output voltage of the inverter and the ground leakage current to obtain the sampling instantaneous value u of the three-phase output to the DC neutral point voltage a , u b and u c , and the sampled instantaneous value i of the ground leakage current, the instantaneous value i of the ground leakage current is taken as the common mode current.

[0033] S2. Common-mode transformation: Perform common-mode transformation on the measured three-phase voltage to obtain the common-mode voltage value u, and the transformation formula is:

[0034] ;(1)

[0035] Among them, k 1 、k 2 、k 3 represent the common-mode transformation coefficients respectively, and there are k 1 +k 2 +k 3 =3. The common-mo...

Embodiment 2

[0050] Such as image 3 As shown, Embodiment 2 of the present invention provides a leakage protection system for mine-used variable frequency drive system including 5 such as figure 2 In the mine variable frequency drive system leakage protection unit shown, among the 5 mine frequency conversion drive system leakage protection units, one of them is set on the bus as a bus protection unit, and the other 4 are set as branch circuit leakage protection units on each On the output terminal of the branch frequency converter.

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to View More

PUM

No PUM Login to View More

Abstract

The invention belongs to the technical field of mining variable-frequency driving, and discloses an electric leakage protection method and system for a mining variable-frequency driving system. The method comprises the following steps: S1 carrying out the four-path synchronous sampling of a three-phase output voltage and a ground leakage current of a frequency converter; S2 performing common-modetransformation on the measured three-phase voltage to obtain a common-mode voltage value; S3 performing Fourier transform on the common-mode voltage and the common-mode current to obtain a harmonic voltage and a harmonic current, and setting the frequency upper limit of the Fourier transform as the switching frequency of the frequency converter; S4 rejecting all harmonic signals of which the voltage amplitude is smaller than a voltage threshold or the current amplitude is smaller than a current threshold; and then successively calculating the phase difference between each harmonic voltage andach eharmonic current with the same frequency in the remaining harmonic waves, if the phase difference is within + / -10 degrees, judging that the resistive circuit occupies the main component, and outputting an electric leakage protection signal. According to the invention, the graded leakage protection function is realized, and the safety and reliability of the mining variable-frequency driving system are improved.

Description

technical field [0001] The invention belongs to the field of variable frequency drive systems for mines, and in particular relates to a leakage protection method and system for variable frequency drive systems for mines. Background technique [0002] With the promotion and use of frequency conversion drive systems in coal mines, especially on airborne equipment, coal shearers, continuous miners, shuttle cars, and bolters mostly use frequency conversion traction systems. Due to the traditional leakage protection system, there must be a grounding resistance. , resulting in only one set of leakage protection at the rear end of the entire transformer. If there are multiple sets, they will inevitably affect each other and cannot work normally. That is, at the back end of the transformer, all electrical equipment share a set of leakage protection, and the insulation status of other electrical equipment is completely dependent on it, which loses the meaning of hierarchical protecti...

Claims

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to View More

Application Information

Patent Timeline
no application Login to View More
Patent Type & Authority Applications(China)
IPC IPC(8): H02H3/34H02H7/10
CPCH02H3/34H02H7/10Y02E40/40
Inventor 曹建文姜铭田克君王健王涛张爱荣胡文芳布朋升许连丙程俊强
Owner TAIYUAN INST OF CHINA COAL TECH & ENG GROUP
Who we serve
  • R&D Engineer
  • R&D Manager
  • IP Professional
Why Eureka
  • Industry Leading Data Capabilities
  • Powerful AI technology
  • Patent DNA Extraction
Social media
Eureka Blog
Learn More
PatSnap group products