Method for determining aging state of ZnO voltage-sensitive resistor disc according to higher harmonic characteristic of leakage current

A varistor and leakage current technology, which is applied in the direction of measuring electricity, measuring electrical variables, measuring devices, etc., can solve the problems of difficulty and difficulty in acquisition, and the measurement results are affected by the voltage of the power grid, and achieve the effect of convenient acquisition and clear characteristics.

Inactive Publication Date: 2016-07-20
TSINGHUA UNIV
View PDF3 Cites 4 Cited by
  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

This method is simple to operate, but since the capacitive current accounts for 90% of the leakage current, the resistive current component that increases with the aging degree is only about 10%, so it is difficult to judge its aging state in the early stage of aging. The old varistor valve will pose a threat to the power system or power system
In addition, other characteristic parameters include the resistive component of leakage current, the fundamental component of leakage current, and the phase angle difference between current and voltage, etc., all of which have problems such as difficult acquisition, relatively large data dispersion, and the measurement results are greatly affected by the grid voltage.

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
  • Method for determining aging state of ZnO voltage-sensitive resistor disc according to higher harmonic characteristic of leakage current
  • Method for determining aging state of ZnO voltage-sensitive resistor disc according to higher harmonic characteristic of leakage current
  • Method for determining aging state of ZnO voltage-sensitive resistor disc according to higher harmonic characteristic of leakage current

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0038] Use an oscilloscope to collect the waveform of the leakage current of the zinc oxide varistor valve at 350V, and save it as a csv file

[0039] Use the MATLAB program to read the file and get the waveform information in the time domain

[0040] Use the MATLAB program to perform Fourier transform on the obtained time-domain waveform, and you can analyze and obtain the 100-order ZnO varistor fundamental wave, 3rd, 5th, 7th, 9th, 99th and other odd harmonics Waveform amplitude of wave current.

[0041] After conducting different times of ZnO varistor impact experiments, repeat the above steps to obtain the change trend of the ratio of the odd leakage current to the fundamental current with the number of impacts.

[0042] figure 1 It is a schematic diagram of the ratio of the odd harmonic current to the fundamental current when the ZnO varistor sheet of the present invention does not appear aging, as figure 1 As shown, after the valve has undergone 100 times of 7KA high-...

Embodiment 2

[0044] Use an oscilloscope to collect the waveform of the leakage current of the zinc oxide varistor valve at 350V, and save it as a csv file

[0045] Use the MATLAB program to read the file and get the waveform information in the time domain

[0046] Use the MATLAB program to perform Fourier transform on the obtained time-domain waveform, and you can analyze the 9th order of the ZnO varistor fundamental wave, 3rd, 5th, 7th, 9th...99th and other odd times The amplitude of the waveform of the harmonic current.

[0047] After conducting different times of ZnO varistor impact experiments, repeat the above steps to obtain the change trend of the ratio of the odd leakage current to the fundamental current with the number of impacts.

[0048] figure 2 It is a schematic diagram of the ratio of the odd harmonic current to the fundamental current when the ZnO varistor sheet of the present invention is aging, as figure 2 As shown, the ratio of each harmonic current of the valve to ...

Embodiment 3

[0050] Use an oscilloscope to collect the waveform of the leakage current of the zinc oxide varistor valve at 350V, and save it as a csv file

[0051] Use the MATLAB program to read the file and get the waveform information in the time domain

[0052]Use the MATLAB program to perform Fourier transform on the obtained time-domain waveform, and you can analyze and obtain the 12th order ZnO varistor fundamental wave, 3rd, 5th, 7th, 9th, 11th and other odd harmonics The amplitude of the waveform of the current.

[0053] After conducting different times of ZnO varistor impact experiments, repeat the above steps to obtain the change trend of the ratio of the odd leakage current to the fundamental current with the number of impacts.

[0054] image 3 It is a schematic diagram of the ratio of the odd harmonic current to the fundamental current when the ZnO varistor sheet of the present invention is severely aged, as shown in image 3 As shown, after the first 5 times of 40kA impact...

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 provides a method for determining aging state of a ZnO voltage-sensitive resistor disc according to higher harmonic characteristic of a leakage current. The leakage current of a ZnO voltage-sensitive resistor valve disc in a high-voltage lightning arrester or shock protecting device (SPD) of a low-voltage system in operation is monitored The leakage current in a time unit is sampled and the waveform data of the leakage current are recorded. Fourier transform is performed on the waveform of the acquired leakage current, thereby obtaining the amplitude of a fundamental wave current and the amplitude of each odd harmonic current in the leakage current. The ratio between the amplitude each odd harmonic current and the amplitude of the fundamental wave current is obtained through calculation, and the ratio is used as a determining basis for the aging state of the voltage-sensitive resistor. The method for determining the key portion, namely aging state in safe and stable operation of the ZnO voltage-sensitive resistor disc is beneficial in that the harmonic characteristic change can be directly seen for determining the aging process according to harmonic analysis on the leakage current of the ZnO voltage-sensitive resistor for determining the aging process, thereby determining residual service life of the valve disc. Compared with existing total leakage current methods, the method of the invention has advantages of convenient acquisition and clear characteristic.

Description

technical field [0001] The invention relates to the field of metal oxide nonlinear materials, in particular to a method for judging the aging state of metal oxide nonlinear materials. Background technique [0002] Various forms of overvoltage have always been the main threat to the safe operation of power systems, and zinc oxide varistors have excellent non-linear operating characteristics and current capacity, and can be connected in parallel to absorb huge currents in the protected line, with zinc oxide voltage The lightning arrester and low-voltage surge protection device (SPD) assembled by the sensitive resistor as the core component are the main equipment for limiting the overvoltage in the power system and power system. Under normal working conditions, little or no current flows through the varistor; when an overvoltage occurs in the line, the resistance of the varistor decreases rapidly, so that a large current flows into the ground through the varistor, thereby avoid...

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 & AuthorityApplications(China)
IPC IPC(8): G01R31/00
CPCG01R31/00
Inventor胡军何金良邬锦波陈水明
OwnerTSINGHUA UNIV