CN-121977742-A - Vacuum degree detection method and detection system for vacuum arc extinguishing chamber based on high-frequency discharge and spectrum analysis

CN121977742ACN 121977742 ACN121977742 ACN 121977742ACN-121977742-A

Abstract

The invention relates to a vacuum degree detection method and a detection system of a vacuum arc-extinguishing chamber based on high-frequency discharge and spectrum analysis, wherein the method excites the interior of the vacuum arc-extinguishing chamber to generate field emission current through a high-frequency electric field, obtains a high-frequency current peak value through spectrum analysis of the field emission current, and determines the vacuum degree according to a pre-constructed standard relation curve of vacuum degree-high-frequency current peak value, wherein the vacuum arc-extinguishing chamber is connected with a high-frequency power supply, the output voltage of the high-frequency power supply is gradually increased to a vacuum gap for breakdown, the voltage waveform in the process is recorded, the total current of a loop is calculated, the equivalent capacitance of the loop is combined, a stable current section between two dielectric breakdown events is selected in the total current, a current peak signal in the section is intercepted, and the total current corresponding to the peak signal is subtracted by the capacitive current component, so that the field emission current is obtained. Compared with the prior art, the method has the advantages of high sensitivity, simplicity and convenience in operation, accurate result and the like.

Inventors

CAO PEI
HU ZHENGYONG
DUAN XIONGYING
LU YANQING
ZHOU GULIANG
LI XUBIN
DING MIN
WANG LIMING
LIAO MINFU
YAN YIKAI
ZHAO HAOMING
SUN JIN

Assignees

国网上海市电力公司
大连理工大学

Dates

Publication Date: 20260505
Application Date: 20251222

Claims (10)

1. The vacuum degree detection method of the vacuum arc-extinguishing chamber based on high-frequency discharge and spectrum analysis is characterized in that the method excites the vacuum arc-extinguishing chamber to generate field emission current through a high-frequency electric field, a high-frequency current peak value is obtained through spectrum analysis of the field emission current, the vacuum degree is determined according to a pre-constructed standard relation curve of vacuum degree-high-frequency current peak value, and the acquisition of the field emission current comprises the following steps: Connecting a high-frequency power supply to the movable contact end of the vacuum arc-extinguishing chamber, gradually increasing the output voltage of the high-frequency power supply to the breakdown of a vacuum gap, recording the voltage waveform in the process, and calculating the total current I t of a loop; calculating a capacitive current component I c by combining the equivalent capacitance of the loop; And selecting a stable current section between two dielectric breakdown events from the total current I t , intercepting a current spike signal in the section, and subtracting the capacitive current component I c from the total current I t corresponding to the spike signal to obtain a field emission current I e .
2. The vacuum degree detection method of a vacuum interrupter based on high-frequency discharge and spectrum analysis according to claim 1, wherein the obtaining of the high-frequency current peak value specifically comprises: And performing fast Fourier transform on the waveform of the field emission current to obtain a spectrogram, and finding out the maximum value of the current amplitude in the high frequency band to serve as the high frequency current peak value.
3. The vacuum degree detection method of a vacuum interrupter based on high-frequency discharge and spectrum analysis according to claim 2, wherein the high frequency band is a frequency component with a fundamental wave frequency of 5 times or more.
4. The vacuum degree detection method for the vacuum arc-extinguishing chamber based on high-frequency discharge and spectrum analysis according to claim 1, wherein when the standard relation curve is constructed, the vacuum degree in the vacuum arc-extinguishing chamber of a certain model is changed stepwise, a high-frequency current peak value corresponding to each vacuum degree value is obtained, and a standard relation curve of vacuum degree-high-frequency current peak value of the vacuum arc-extinguishing chamber of the model is drawn.
5. The vacuum degree detection method of a vacuum interrupter based on high-frequency discharge and spectrum analysis according to claim 1, wherein the stable current section is a current section with a current deviation of + -5%.
6. The vacuum degree detection method of the vacuum arc-extinguishing chamber based on high-frequency discharge and spectrum analysis according to claim 1, wherein when the vacuum degree is determined according to a pre-constructed standard relation curve of vacuum degree-high-frequency current peak value, the actual vacuum degree value in the current arc-extinguishing chamber is calculated through interpolation or fitting.
7. The vacuum degree detection method of the vacuum interrupter based on high-frequency discharge and spectrum analysis according to claim 1, wherein the high-frequency power supply outputs a high-frequency sinusoidal signal with a frequency of 20kHz and an output voltage adjustable in a range of 0 to 500V.
8. The vacuum degree detection method of the vacuum interrupter based on high-frequency discharge and spectrum analysis according to claim 1, wherein the gap between the movable contact and the static contact of the vacuum interrupter is preset and adjusted between 0 and 10 mm during detection.
9. The vacuum degree detection system of the vacuum arc-extinguishing chamber based on high-frequency discharge and spectrum analysis is characterized by comprising a high-frequency power supply (1), a step-up transformer (2), a current limiting resistor (3), a sampling resistor (5), a first high-voltage probe (6), a second high-voltage probe (7) and an upper computer, wherein, The high-frequency power supply (1) outputs a high-frequency sinusoidal signal, the positive electrode of the high-frequency sinusoidal signal is connected to the movable contact end of the vacuum arc-extinguishing chamber (4) through the current-limiting resistor (3) after the high-frequency sinusoidal signal is boosted by the boosting transformer (2), and the negative electrode of the high-frequency sinusoidal signal is grounded; The static contact end of the vacuum arc extinguishing chamber (4) is grounded through a sampling resistor (5); the first high-voltage probes (6) are connected in parallel with two ends of the vacuum arc extinguishing chamber (4) and are used for measuring the applied high-frequency voltage; the second high-voltage probe (7) is connected in parallel with two ends of the sampling resistor (5) and is used for measuring the voltage drop of the sampling resistor (5); The upper computer is used for acquiring a high-frequency voltage waveform, the high-frequency voltage and the voltage drop in the vacuum gap breakdown process, calculating a loop total current I t based on the voltage drop, calculating a capacitive current component I c according to the high-frequency voltage combined with a loop equivalent capacitance, selecting a stable current section between two dielectric breakdown events in the total current I t , intercepting a current peak signal in the section, subtracting the capacitive current component I c from the total current I t corresponding to the peak signal to obtain a field emission current I e , analyzing a frequency spectrum of the field emission current to obtain a high-frequency current peak value, and determining the vacuum degree according to a pre-constructed standard relation curve of vacuum degree and high-frequency current peak value.
10. The vacuum interrupter vacuum degree detection system based on high frequency discharge and spectrum analysis according to claim 9, wherein the current limiting resistor (3) and the sampling resistor (5) are precise non-inductive resistors.

Description

Vacuum degree detection method and detection system for vacuum arc extinguishing chamber based on high-frequency discharge and spectrum analysis Technical Field The invention belongs to the technical field of vacuum circuit breakers, and particularly relates to a vacuum degree detection method and a detection system of a vacuum arc-extinguishing chamber based on high-frequency discharge and spectrum analysis. Background Along with the continuous promotion of intelligent power grid construction and distribution network automation level in China, vacuum circuit breakers have become dominant switching equipment in the field of medium-voltage distribution (especially 12kV-40.5kV voltage level) due to the outstanding advantages of excellent arc extinguishing performance, long service life, simple maintenance, environmental friendliness and the like. It is counted that the number of vacuum circuit breakers in operation has taken an absolute advantage, and the average operating life thereof continues to increase, and the problem of equipment aging is increasingly prominent. In the face of tremendous plant retrofit pressures, developing state-based precision maintenance (CBM) and life assessment is particularly important and economical. The vacuum arc-extinguishing chamber is used as the only core component for realizing the current breaking function of the vacuum circuit breaker, and the integrity of the performance directly determines the safety and reliability of the whole circuit breaker. The most critical index of the performance of the vacuum arc-extinguishing chamber is the vacuum degree in the vacuum arc-extinguishing chamber. Vacuum interrupters are typically pumped and maintained at extremely high levels (better than the order of 10-4 Pa) at the time of manufacture. However, the vacuum is not constant during long-term storage, transport, installation and operation. The mechanism leading to its degradation is complex and mainly includes: 1. chronic leaks-the seal weld between the ceramic or glass insulating shell and the metal end cap may have microscopic defects, slow leakage under thermo-mechanical stress cycling, and fatigue microcracking of the bellows may also become a leak path. 2. Internal gassing, namely releasing gas (such as H2, CO2 and the like) adsorbed on the surface or dissolved in the inner metal parts (such as contacts, shielding cases and supporting rods) of the arc extinguishing chamber under the action of arc heat and electric field. 3. Permeation leakage-small molecular gases such as hydrogen gas may permeate through the glass or ceramic housing itself. Once the vacuum level drops below the critical value (typically considered to be on the order of less than 10-1 Pa to 10-2 Pa, the specific value will vary depending on the product design) its dielectric strength and breaking capacity will drop dramatically. When the switch is opened, residual gas molecules are ionized by an electric arc to form plasma which cannot be extinguished, so that the switch fails to be opened, and disastrous accidents such as breaker explosion and bus short circuit can be possibly caused. Therefore, the vacuum arc-extinguishing chamber in operation or standby is subjected to regular and accurate vacuum degree detection, and is an indispensable technical link for preventing accidents, evaluating the residual life of equipment and guiding maintenance decisions. At present, the vacuum degree detection method mainly adopted in the engineering sites and laboratories at home and abroad and the limitations thereof are as follows: 1. The magnetic control discharge method is a relatively mainstream quantitative detection method at present. The principle is that an axial exciting coil is applied outside the arc extinguishing chamber, and a direct current or pulse high voltage is applied between contacts. The magnetic field causes electrons generated by discharge to do spiral motion, so that the probability of ionization collision is increased, and the discharge current is related to the vacuum degree. However, this method has fatal disadvantages of heavy equipment (large-capacity exciting coil and power supply), complicated wiring, severe requirements for the synchronism of magnetic field and electric field, large influence of contact materials, surface states and gap distances on detection results, and high data dispersion. Most importantly, for circuit breakers already installed in switchgear, the application of external coils is extremely difficult or even impossible, and the practicality is compromised. 2. The industrial frequency AC voltage withstand method is a qualitative or semi-quantitative destructive test method. And applying a certain power frequency alternating voltage to the arc extinguishing chamber to observe whether breakdown occurs. If the vacuum is not broken down at the voltage specified by the standard, the vacuum is roughly regarded as "acceptable". The method cannot give specific vacuum degree valu