CN117198801A - Composite structure vacuum arc-extinguishing chamber suitable for capacitive current break - Google Patents
Composite structure vacuum arc-extinguishing chamber suitable for capacitive current break Download PDFInfo
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- CN117198801A CN117198801A CN202310273972.7A CN202310273972A CN117198801A CN 117198801 A CN117198801 A CN 117198801A CN 202310273972 A CN202310273972 A CN 202310273972A CN 117198801 A CN117198801 A CN 117198801A
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- extinguishing chamber
- shielding cover
- movable end
- switching
- vacuum arc
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- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 claims description 5
- 229910052804 chromium Inorganic materials 0.000 claims description 5
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Abstract
The invention provides a composite structure vacuum arc-extinguishing chamber suitable for switching capacitive load, which is characterized in that: the main shielding cover is of a structure with two ends provided with edge chamfers. The movable end contact of the vacuum arc-extinguishing chamber contact consists of a material A, and the circular ring and the shielding cover consist of a material B. In the closing process, the distance between the circular ring material B and the main shielding cover material B is smaller than the distance between the pair of movable end contact materials A, so that the circular ring material B and the main shielding cover material B are subjected to pre-breakdown; in the switching-off process, an opening current arc is established on the surfaces of the two movable end contact materials A and A, and the current is opened by the movable end contact material A. The invention realizes the separation of the fusion welding resistance and the breaking resistance of the contact structure of the vacuum arc extinguishing chamber, thereby ensuring the insulation strength between the contacts.
Description
Technical Field
The invention relates to a vacuum arc-extinguishing chamber, in particular to a vacuum arc-extinguishing chamber structure suitable for switching capacitive load and a control method thereof.
Background
Reactive power compensation plays an important role in maintaining safe, high-quality and economical operation of the power grid. There are a large number of capacitive loads and inductive loads in the power system, which loads generate a large amount of reactive power during operation of the power system, which reactive power can cause the system voltage to deviate from the rated value and increase the system loss, so that reactive power compensation is necessary to ensure the voltage level of the power system and improve the transmission capacity. According to the operation experience of the power grid, 1.2-1.4 kvar reactive power is required to maintain the normal working voltage of the power system every time 1kW of active power is generated.
During operation of an actual power system, the grid load frequently fluctuates, and therefore, the capacitor bank for reactive compensation is frequently thrown into and cut off from the system to maintain the stability of the system voltage. Investigation shows that in a power system, on average, about 300 times of switching operation can be performed on 60% of capacitor banks each year, and about 700 times of switching operation can be performed on the other 30% of capacitor banks each year. In the power system, the switching task of the capacitor bank for reactive power compensation is mainly completed by the power switch equipment, which shows that the power switch has frequent switching operation for 1-2 times per day on average. In the summer peak period of electricity consumption in China, the capacitor bank is switched every day to carry out reactive compensation for times even up to 6 times. The frequent operation condition puts high demands on the switching capacity and stability of the switching capacitor bank switching device.
The prior power switching equipment applied to the reactive compensation field of the power system mainly comprises SF (sulfur hexafluoride) 6 Circuit breakers and vacuum circuit breakers. SF (sulfur hexafluoride) 6 The characteristic ability to strongly adsorb electrons to external free electrons is called electric affinity. SF (sulfur hexafluoride) 6 Is tens times higher than air, and the SF is caused by extremely strong electric affinity 6 The gas has excellent insulating properties. In addition, SF 6 The high thermal conductivity of the gas enables SF 6 The gas has excellent arc extinguishing capability. SF (sulfur hexafluoride) 6 When the circuit breaker is applied to reactive compensation of a power system, the probability of heavy breakdown after capacitive current is broken is lower, and the circuit breaker has reliable insulating performance. However, SF 6 The use of gases in the international switching field is severely limited. Currently, many developed countries have come out of various controlsBy SF 6 Gas regulations, e.g. the Australian government began to regulate SF in 2012 6 The gas has a collection of carbon emissions tax of up to 57 ten thousand dollars/t. SF (sulfur hexafluoride) 6 The problem of the greenhouse effect of gases is the core that restricts their use: SF (sulfur hexafluoride) 6 The gas is a strong greenhouse gas, and 6 greenhouse gases (CO) are pointed out in the "Kyoto protocol" passed in 1997 2 、CH 4 、N 2 O、HFCS、PFCS、SF 6 ) In SF 6 The gas is one of the strongest greenhouse effect, and its global warming coefficient is CO 2 And its chemical characteristics are very stable, with half-lives as long as 3200 years. Pure SF 6 The gas is colorless, odorless, nontoxic and nonflammable inert gas, but SF is carried out under the action of high temperature of open-close arc 6 Will decompose toxic chemical gases, such as SF 4 、SOF 2 Etc. These toxic decomposition products follow SF 6 The discharge of the gas diffuses into the outside air and will directly harm the health of the human body. And SF (sulfur hexafluoride) 6 The gas inevitably contains impurities such as moisture and oxygen during the manufacturing process. Chemically active H 2 O and O 2 Will be easy to be matched with SF 6 The decomposition products of the gas under the high temperature of the open-close arc generate new chemical reaction to generate acid harmful substances such as H 2 SO 3 HF, etc., which can cause erosion damage to the switching arc chute components. In addition, SF 6 The mechanical life of the circuit breaker cannot well meet the requirement of frequent operation in the reactive power compensation system, and SF needs to be replaced frequently to ensure the safety and reliability of reactive power compensation of the system 6 The circuit breaker thus causes an increase in reactive compensation operation costs of the power system. Therefore, combining two factors of economy and environmental protection, more ideal switching equipment is searched for to reduce and replace SF 6 Circuit breakers have become a necessary choice and trend in the field of reactive power compensation of power systems.
And the same voltage level SF 6 Compared with the circuit breaker product, the vacuum circuit breaker is more suitable for the reactive power compensation field in the power system by virtue of the excellent characteristics. The main advantages are as follows:
1) Is environment-friendly. No greenhouse effect gas, no special treatment is needed after the vacuum circuit breaker reaches the service life, and the vacuum circuit breaker can not cause fire and explosion accidents and can not generate environmental pollution.
2) The maintainability is good. The vacuum arc-extinguishing chamber is used as a core component of the vacuum circuit breaker, the service life of the arc-extinguishing chamber is maintenance-free, the switching-on and switching-off operation work is small (the operation work of the vacuum circuit breaker is SF under the same voltage level) 6 20% or less of the circuit breaker) can reduce the maintenance requirements of the operating mechanism.
3) The breaking performance is good. The medium strength after the breaking recovers quickly, the burning time is short (namely, the short burning time is usually within one current half wave), the medium has fault current breaking capability after the breaking and time delay breakdown, and the internal components of the arc extinguishing chamber can not be damaged by repeated breakdown or reburning.
4) The environmental impact is small. The electrical performance of the arc extinguishing chamber is not affected by low-temperature environment.
5) Long mechanical and electrical life. Vacuum interrupters have tens of thousands of mechanical action life and have a high number of failure current turn-off times of electrical life (even if the turn-off current is a short circuit current).
In the power system, the working conditions of switching capacitive load mainly include: switching of an empty overhead line, switching of an empty cable, switching of a single capacitor bank, switching of a back-to-back capacitor bank and switching of a filter bank. Compared with short-circuit current of tens of kiloamperes, capacitive load switching rated current is usually smaller (about several amperes), and capacitive current opening and closing is a relatively easy task for a vacuum circuit breaker, however, in experimental research and actual running conditions of a power system, the problem of heavy breakdown is more serious when the vacuum circuit breaker switches the capacitive load, and the problem of heavy breakdown is found to be high, particularly under the working condition that back-to-back capacitor banks are subjected to reactive compensation. Heavy breakdown can cause undesirable overvoltage problems or high-frequency transient processes affecting the power quality of the power grid, can cause damage to circuit breakers or other electrical equipment, and can also threaten the safe operation of the power system. The method makes the research on how to reduce the heavy strike probability of the switching capacitive load of the vacuum circuit breaker become a research hot spot in the field of vacuum switches at home and abroad in recent years.
However, in the existing design process of the vacuum arc-extinguishing chamber, a pair of moving and static contacts with the same contact materials is basically adopted to complete the operation of switching the capacitive load of the vacuum circuit breaker, so that the damage effect of closing inrush current to the contact surface of the vacuum arc-extinguishing chamber cannot be avoided, and the damaged contact surface is the root cause of heavy breakdown in the switching-off process.
Disclosure of Invention
In order to solve the problems in the prior art, the invention aims to provide a composite structure vacuum arc-extinguishing chamber suitable for capacitive current breaking, which separates a switching-on fusion welding resistance function and a switching-off function, uses a shielding cover material with excellent fusion welding resistance to bear switching-on high-frequency surge current, uses a contact material with excellent switching-off performance to realize the switching-off function, can be used for switching capacitive loads, such as back-to-back capacitor banks, single capacitor banks and the like, and is particularly suitable for the reactive compensation field of a power system.
In order to achieve the above purpose, the invention adopts the following technical scheme:
a composite structure vacuum arc-extinguishing chamber suitable for switching capacitive load is characterized in that: the main shielding cover is of a structure with two ends provided with edge chamfers.
The movable end contact of the vacuum arc-extinguishing chamber contact consists of a material A, and the circular ring and the shielding cover consist of a material B. In the closing process, the distance between the circular ring material B and the main shielding cover material B is smaller than the distance between the pair of movable end contact materials A, so that the circular ring material B and the main shielding cover material B are subjected to pre-breakdown; in the switching-off process, an opening current arc is established on the surfaces of the two movable end contact materials A and A, and the current is opened by the movable end contact material A.
The movable end contact material A is a chromium-containing contact material; and a tungsten-containing contact material is adopted between the circular ring material B and the main shielding cover material B.
The chromium-containing contact material is CuCr.
The tungsten-containing contact material is WCu.
A vacuum arc-extinguishing chamber is composed of the composite structure of the vacuum arc-extinguishing chamber, a shell, a shielding cover and a corrugated pipe.
Compared with the prior art, the invention has the following advantages: in the closing process, the distance between the circular ring material B and the main shielding cover material B is smaller than the distance between the pair of movable end contact materials A, so that the circular ring material B and the main shielding cover material B are subjected to pre-breakdown; in the switching-off process, an opening current arc is established on the surfaces of the two movable end contact materials A and A, and the current is opened by the movable end contact material A. The separation of the fusion welding resistance and the breaking resistance of the contact structure of the vacuum arc extinguishing chamber is realized, so that the insulation strength between the contacts is ensured. Therefore, the contact structure with the composite material can effectively improve the fusion welding resistance of the vacuum arc-extinguishing chamber and reduce the probability of heavy strike-through after the capacitive current of the vacuum arc-extinguishing chamber is cut off, can be assembled in various vacuum arc-extinguishing chambers, and is particularly suitable for the reactive compensation field of power systems.
Drawings
FIGS. 1, 2 and 3 are schematic views of the structure of the present invention;
FIG. 4 is a schematic diagram of the present invention when the capacitive load is closed, wherein the two movable contacts are at the moment of inrush pre-breakdown before contact;
fig. 5 and 6 are schematic structural diagrams of the present invention at the time of complete closing;
FIG. 7 is a schematic diagram of the breaking arcing process after separation of two moving end contacts in accordance with the present invention;
FIG. 8 is a schematic diagram of the structure of the present invention at the time of complete opening;
reference numerals: 1: bellows, 2: ring, 3: first movable conductive rod, 4: first moving end contact, 5: second moving end contact, 6: second movable conductive rod, 7: ring, 8: bellows, 9: main shielding cover
Description of the embodiments
The invention is described in further detail below with reference to the drawings and the detailed description.
As shown in fig. 1, the vacuum interrupter structure suitable for switching capacitive load of the present invention is composed of movable conductive rods 3 and 6, movable terminal contacts 4 and 5, and rings 2 and 7 respectively fixed to the movable conductive rod 3 and the movable conductive rod 6. The movable end contact consists of a material A, and the shielding cover and the circular ring consist of a material B.
The movable end contact material A is a chromium-containing contact material, preferably a contact material such as CuCr25, cuCr30, cuCr40, cuCr50 and the like.
The ring material B and the shielding cover material B are made of tungsten-containing contact materials, preferably WCu, such as WCu10, WCu20, WCu30 and other contact materials.
The vacuum arc-extinguishing chamber consists of the vacuum arc-extinguishing chamber composite structure, a shell, a shielding cover and a corrugated pipe.
The working principle of the composite contact structure of the vacuum arc-extinguishing chamber is as follows:
during the closing process, the movable conducting rods 3 and 6 move towards each other under the action of driving force, and when the movable contacts 4 and 5 are not contacted, the circular rings 2 and 7 at the two ends are contacted with the shielding cover 9, as shown in fig. 4. At the moment, the loop is conducted, from the angle of electric field distribution, switching-on pre-breakdown occurs between the circular ring and the main shielding case, the circular ring and the main shielding case are made of materials with excellent fusion welding resistance, the ablation damage effect of high-frequency surge current on the surface of the contact can be effectively reduced, and the circular ring and the main shielding case are in instant contact only because the main shielding case is of a two-end outwards-turned structure; as the moving conductive rods 3 and 6 continue to move, the moving contacts 4 and 5 contact to complete the closing process, as shown in fig. 5.
In the process of opening the switch, the movable conducting rods 3 and 6 are driven to move back and forth, the upper surfaces of the movable contacts 4 and 5 are separated from each other, and an arc is generated, as shown in fig. 7. At this time, the separation distance of the movable end contacts is smaller than the separation distance between the circular rings and the main shielding cover, and the separation arc is generated between the movable end contacts at two sides from the angle of electric field distribution, so that the movable end contacts mainly complete the current breaking function, the movable end contacts at two ends adopt materials with high current breaking capacity and excellent pressure resistance, so that the insulation strength between the contacts is ensured, the time interval from the start of the separation action to the contact between the circular rings 2 and 7 and the shielding cover 9 is smaller than 5ms, and according to IEC and national standard, the breakdown generated in 5ms (T/4) after the separation is called as "reburning", no overvoltage is generated, and therefore, as the separation process is continued, even if the circular rings 2 and 7 at two ends are contacted with the shielding cover 9, the arc "reburning" is generated, no overvoltage is generated; as the moving conductive bars 3 and 4 continue to move, the rings 2 and 7 are thoroughly separated from the main shield 9, completing the breaking process, as shown in fig. 8.
Claims (6)
1. A vacuum arc-extinguishing chamber structure suitable for switching capacitive load and a control method thereof. The method is characterized in that: the vacuum arc-extinguishing chamber comprises a pair of movable conducting rods, a pair of movable end contacts, a pair of circular rings and a main shielding cover; the movable conducting rod is fixedly sleeved with the circular ring, and the main shielding cover is of a structure with edge chamfer at two ends.
2. A vacuum interrupter structure adapted for switching capacitive loads as defined in claim 1 wherein: the movable end contact of the vacuum arc-extinguishing chamber contact consists of a material A, and the circular ring and the shielding cover consist of a material B. In the closing process, the distance between the circular ring material B and the main shielding cover material B is smaller than the distance between the pair of movable end contact materials A, so that the circular ring material B and the main shielding cover material B are subjected to pre-breakdown; in the switching-off process, an opening current arc is established on the surfaces of the two movable end contact materials A and A, and the current is opened by the movable end contact material A.
3. A vacuum interrupter structure according to claim 2 adapted for switching capacitive loads, wherein: the movable end contact material A is a chromium-containing contact material; and a tungsten-containing contact material is adopted between the circular ring material B and the main shielding cover material B.
4. A vacuum interrupter composite structure adapted for switching capacitive loads according to claim 3, wherein: the chromium-containing contact material is CuCr.
5. A vacuum interrupter composite structure adapted for switching capacitive loads according to claim 3, wherein: the tungsten-containing contact material is WCu.
6. A vacuum interrupter composite structure according to claims 1-5, wherein: and the vacuum arc-extinguishing chamber is formed by the vacuum arc-extinguishing chamber, the shell and the corrugated pipe.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310273972.7A CN117198801A (en) | 2023-03-21 | 2023-03-21 | Composite structure vacuum arc-extinguishing chamber suitable for capacitive current break |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310273972.7A CN117198801A (en) | 2023-03-21 | 2023-03-21 | Composite structure vacuum arc-extinguishing chamber suitable for capacitive current break |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN117198801A true CN117198801A (en) | 2023-12-08 |
Family
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202310273972.7A Pending CN117198801A (en) | 2023-03-21 | 2023-03-21 | Composite structure vacuum arc-extinguishing chamber suitable for capacitive current break |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN117198801A (en) |
-
2023
- 2023-03-21 CN CN202310273972.7A patent/CN117198801A/en active Pending
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