CN113054534B - Method for improving arc extinguishing efficiency of multi-cavity structure by using magnetic field - Google Patents
Method for improving arc extinguishing efficiency of multi-cavity structure by using magnetic field Download PDFInfo
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- CN113054534B CN113054534B CN202110210186.3A CN202110210186A CN113054534B CN 113054534 B CN113054534 B CN 113054534B CN 202110210186 A CN202110210186 A CN 202110210186A CN 113054534 B CN113054534 B CN 113054534B
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01T—SPARK GAPS; OVERVOLTAGE ARRESTERS USING SPARK GAPS; SPARKING PLUGS; CORONA DEVICES; GENERATING IONS TO BE INTRODUCED INTO NON-ENCLOSED GASES
- H01T1/00—Details of spark gaps
- H01T1/02—Means for extinguishing arc
- H01T1/04—Means for extinguishing arc using magnetic blow-out
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Abstract
The invention relates to the technical field of overvoltage protection devices, in particular to a method for improving arc extinguishing efficiency of a multi-cavity structure by using a magnetic field, which can improve the performance of the multi-cavity arc extinguishing structure. The method for improving the arc extinguishing efficiency of the multi-cavity structure by the magnetic field can further accelerate the movement of arc plasma in the structure when the multi-cavity structure is broken down to generate an arc, shorten the arc spraying and extinguishing time and improve the arc extinguishing efficiency. The invention sets a non-constant magnetic field on the basis of the original cavity structure, the magnetic induction intensity of the magnetic field is 0.1-5T, and the direction of the magnetic field is vertical to the central axis between electrodes in an arc extinguishing cavity unit and the central axis of a cavity nozzle. Through the magnetic field, on the basis of pneumatic pressure acceleration, the arc plasma is subjected to Lorentz force towards the direction of the nozzle, the movement of the arc plasma is accelerated, and the arc spraying and extinguishing time is shortened, so that the arc extinguishing efficiency of a multi-cavity structure is improved.
Description
Technical Field
The invention relates to the technical field of overvoltage protection devices, in particular to a method for improving arc extinguishing efficiency of a multi-cavity structure by using a magnetic field.
Background
Along with the development of social economy, people have more and more large demand on electricity, and the requirements on technical and economic indexes of power grid operation of various voltage levels are increasingly improved. The power distribution network is an important component of a power system, is directly oriented to vast power users, is responsible for distributing a network of electric energy, and transmits the electric energy to thousands of households, and is closely related to production activities and lives of people.
The lightning protection measures of the existing distribution lines are obviously insufficient, if the traditional parallel gap device is installed, although the lightning protection device has the advantages of convenience in installation, low price, capability of protecting insulators from arc ignition and the like, the lightning trip-out rate is often improved to a certain extent. And distribution lines suffers thunderbolt after, the high probability can cause the thunderbolt tripping operation to lead to the emergence of power failure accident, and the distribution lines still can cause serious consequences such as insulator burn, explode and split, fall cluster and circuit arrester puncture simultaneously thunderbolt, and some circuit still can be because of the thunderbolt broken string, and it is very serious to advance to join in marriage net thunderbolt trouble, needs a more effectual lightning protection measure urgently.
The researchers have proposed that the multi-chamber structure has good arc extinguishing performance, can make up for the defect that the traditional parallel gap device cannot spontaneously extinguish arc, and reduces the trip rate of lightning stroke, but the arc extinguishing capability of the existing chamber is limited, so that the actual device is large in size and difficult to install and use. The multi-cavity structure arc quenching capacity is realized by that arc plasma is pushed to move to realize arc quenching by narrow semi-closed pneumatic pressure, and the cavity structure can only be optimized by enhancing the pneumatic pressure, but great challenges are brought to the structure processing technology and material selection.
Disclosure of Invention
In order to solve the above problems, the present invention provides a method for improving arc extinguishing efficiency of a multi-chamber structure by using a magnetic field. The invention starts from the angle of accelerating the arc plasma, realizes acceleration by reasonably arranging the magnetic field in the quenching structure, combines pneumatic pressure and Lorentz force for common acceleration compared with a basic structure, can effectively improve the average speed of the arc plasma movement in the arc quenching time, improves the arc extinguishing efficiency of a multi-cavity structure and shortens the quenching time.
The technical scheme adopted by the invention is as follows:
a method for improving the arc extinguishing efficiency of a multi-chamber structure by utilizing a magnetic field is characterized in that the magnetic field is arranged in a quenching structure, when an arc is generated between electrodes of the quenching structure, arc plasma moves towards the necking direction of the quenching structure through pneumatic pressure, and the arc plasma is superposed with Lorentz force which accelerates to move along the necking direction under the action of the magnetic field during the movement.
Preferably, the direction of the magnetic field is specifically set as follows: if the central axis of the nozzle in the quenching structure and the connecting line of the high-low pressure ball electrode are defined as vectors respectively
The direction and vector of the magnetic field
And (5) the consistency is achieved.
Preferably, the magnetic field is a non-constant magnetic field, the magnetic field is uniformly distributed in the magnetic field area, the size of the magnetic field changes with time, and the magnetic field shows a rule that the size of the magnetic field increases and then decreases with time, and a function B-B is specifically selectedm×A[exp(-Bt)-exp(-Ct)]Corresponding magnetic field, wherein BmWhen the peak value of the magnetic field is 0.1 to 5T, A, B, C is constant, T is time, and the unit is mus.
Preferably, the magnetic field region covers a discharge section of the quenching structure, wherein the discharge section covers a discharge electrode and an air gap space of an arc between the electrodes.
Preferably, the arc extinguishing efficiency is the average speed V of the arc plasma within the selected time T1avCharacterized by the formula Vav ═ S/T1The average velocity of the arc plasma can be derived, where T1 is selected for different current levels1100-800 mus, S is 0-T1The area of the velocity curve envelope, which is the integral of the prescribed function, is determined over a period of time.
Preferably, the method for improving the arc extinguishing efficiency of the multi-chamber structure by using the magnetic field can be used for manufacturing the lightning protection device of the multi-chamber structure.
The invention has the beneficial effects that:
according to the method for improving the arc extinguishing efficiency of the multi-chamber structure by using the magnetic field, the time-varying magnetic field is effectively added in the original multi-chamber structure, and the Lorentz force along the movement direction is superposed when the arc plasma moves, so that the average speed of the arc plasma is accelerated, the arc extinguishing efficiency of the original structure can be improved, and the arc extinguishing time is shortened. Compared with a method of adding electric field acceleration or enhancing pneumatic pressure, the magnetic field acceleration is easier to realize than the structure processing problem caused by enhancing the pneumatic pressure acceleration, and compared with the electric field acceleration, more cost is not spent on insulation setting. Due to the special arrangement of the magnetic field, the method can quickly improve the plasma speed of the electric arc in the initial stage of the electric arc development, reduce the size of the magnetic field in the final stage of acceleration, and has higher accelerated conversion rate of the corresponding magnetic field.
Therefore, from the viewpoints of engineering design, economy, convenience and line safety, the method for improving the arc extinguishing efficiency of the multi-cavity structure by using the magnetic field can improve the arc extinguishing performance of the multi-cavity lightning protection device, thereby effectively treating lightning stroke accidents of distribution network lines, reducing line faults and having good application prospects.
Drawings
FIG. 1 is a schematic view of the magnetic field direction;
FIG. 2 is a schematic view of the field effect range;
FIG. 3 is a block diagram of an arc extinguishing chamber unit;
FIG. 4 is a graph of the velocity of the gas flow in the chamber over time under different magnetic field conditions.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings of the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without inventive effort based on the embodiments of the present invention, are within the scope of the present invention.
Example 1
As shown in fig. 1, is a time varying magnetic field direction schematic diagram arranged in a single quenching chamber unit, wherein
Is the central axis of the inner nozzle of the quenching structure,
the direction and vector of the magnetic field B are the connection line of high and low voltage ball electrodes
The direction of the central axis of the nozzle in the quenching structure is vertical to the connecting line of the high-low voltage ball electrode, and the arc plasma can be subjected to the magnetic fieldThe lorentz force is in the direction of the throat.
As shown in fig. 2, which is a schematic view of the magnetic field region provided in the present embodiment, the magnetic field range 1 mainly covers the discharge section 2 of the quenching structure, wherein the discharge section 2 is an air gap space 3 covering the discharge electrode and the arc between the electrodes. The magnetic field specifically set in this example is: b ═ 5 × 2.453[ exp (-0.77t) -exp (-2.5t)]Corresponding to the peak size BmIs 5T.
As shown in fig. 3, in this embodiment, a quenching structural unit with a three-level necking structure is adopted, the outer wall of the quenching structural unit is coated with a material with good insulating property, such as epoxy resin, and the like, the spherical electrode is a metal spherical electrode 5, the radius R is 5mm, and the gap d1 between the two spherical electrodes is 2 mm; the length d2 of the discharge section 2 is 6mm, the opening diameter d3 is 2mm, the acceleration section 4 adopts a three-stage necking structure, the radius of the bottom of each stage of necking is the same as that of the straight section, the opening diameter d4 of the necking is 1mm, and the opening diameter d5 is 3 mm.
Simulation experiment verification:
a magnetofluid simulation model of the quenching structure unit is built by utilizing COMSOL Mutipsics software, the motion characteristics of electric arcs in a cavity of the quenching structure are researched, so that the arc quenching capacity of the quenching structure is analyzed, and the effectiveness of the method for improving the arc extinguishing efficiency of the multi-cavity structure by utilizing the magnetic field is verified.
The magnetic fluid simulation model described in this embodiment is a two-dimensional magnetic fluid model of multiple physical fields such as a coupling electromagnetic field, an airflow field, a thermal field, an environmental magnetic field and the like, and specifically is a two-dimensional magnetic fluid model based on three conservation laws and maxwell's equations of a Navier-Stokes equation of hydrodynamics, mutual coupling of fields is realized by taking temperature T as a basic quantity of each physical field, reasonable assumptions are provided, such as conditions of local thermodynamic equilibrium, arc plasma being newtonian fluid and the like, reasonable parameters and boundary conditions are selected for modules such as an electrostatic field, a fluid and the like in software to establish a simulation model, and parameters capable of representing arc motion characteristics of a quenching structural unit in the model include electric potential at two ends of an electrode, arc temperature, arc conductivity and pneumatic pressure.
In the invention, the average speed V of the arc motion isavThe arc extinguishing efficiency of the quenching structure is characterized, so the arc extinguishing device is used in simulation calculationThe body focuses on this parameter, arc speed. In the simulation of the embodiment, 1kA impulse lightning current is selected, and the motion characteristics of the electric arc are researched under the three conditions of no magnetic field, constant magnetic field and time-varying magnetic field. As shown in fig. 4, the arc speed curves corresponding to different conditions are not difficult to see from the speed curves S2 and S3, the arc speed is significantly increased after the magnetic field is added, for example, the speed peak of the speed curve S1 is about 211m/S when the magnetic field is not added, but the speed peaks of the speed curves S2 and S3 are 330m/S and 313m/S respectively after the magnetic field is added, and the arc speed peak is significantly increased. The velocity curves S2 and S3 after further adding the magnetic field are both above the original curve S1, and the average velocity V of the arc motion can be easily seenavThere is also a lift.
For analyzing arc motion average velocity VavThe improvement efficiency, time T selected in this embodiment1The velocity curve was fitted by Matlab software at 400 μ s and then varied from 0 to T1The integral of a given function, i.e. the area S of the envelope of the speed curve, is determined over a period of time, finally Vav＝S/T1. According to the solving method, the average speed of the arc motion corresponding to the three conditions is v1＝25.9m/s，v2＝48.3m/s，v346.9 m/s. It is easy to see v3At v1The improvement is 80 percent on the basis. Further, v is compared2、v3The difference between the two is not large, and meanwhile, the curve shows that the magnetic field has little influence on the acceleration effect of the arc motion when the time is longer, so that the situation that a constant uniform magnetic field is not needed when the magnetic field is actually added can be shown, and the limitation of the constant uniform magnetic field is larger, so that the acceleration effect of the magnetic field is good, and the arc extinguishing efficiency of the multi-cavity structure can be improved.
In summary, the method for improving the arc extinguishing efficiency of the multi-chamber structure by using the magnetic field in the invention can improve the arc extinguishing efficiency of the multi-chamber structure and shorten the arc extinguishing time.
Claims (5)
1. A method for improving arc extinguishing efficiency of a multi-cavity structure by using a magnetic field is characterized in that: the method for improving the arc extinguishing efficiency of the multi-cavity structure by using the magnetic field is realized by quenching arcThe structure is internally provided with a magnetic field, when electric arcs are generated between electrodes of the quenching structure, the electric arc plasma moves towards the necking direction of the quenching structure through pneumatic pressure, and in the moving process, the electric arc plasma is superposed with a Lorentz force which accelerates to move along the necking direction under the action of the magnetic field; the magnetic field is a non-constant magnetic field, is uniformly distributed in a magnetic field area, changes along with time in size, shows a rule of increasing and then decreasing along with time, and specifically selects a function
Corresponding magnetic field, wherein BmAnd (3) the peak value of the magnetic field is expressed by A, B, C as a constant according to the value of 0.1-5T, T is time, and the unit is expressed as mu s.
2. The method for improving arc extinguishing efficiency of a multi-chamber structure by using a magnetic field according to claim 1, wherein: the direction of the magnetic field is specifically set as follows: if the central axis of the nozzle in the quenching structure and the connecting line of the high-low pressure ball electrode are defined as vectors respectively
The direction and vector of the magnetic field
And (5) the consistency is achieved.
3. The method for improving arc extinguishing efficiency of a multi-chamber structure by using a magnetic field according to claim 1, wherein: the magnetic field region covers a discharge section of the quenching structure, wherein the discharge section covers a discharge electrode and an air gap space of an electric arc between the electrodes.
4. The method for improving arc extinguishing efficiency of a multi-chamber structure by using a magnetic field according to claim 1, wherein: the arc extinguishing efficiency is the average speed V of the arc plasma in the selected time T1avCharacterized by the formula Vav = S/T1The average velocity of the arc plasma can be derived, with T1 being selected for different current levelsThe situation has T1= 100-800 μ S, S is 0-T1The area of the velocity curve envelope, which is the integral of the prescribed function, is determined over a period of time.
5. The method for improving arc extinguishing efficiency of a multi-chamber structure by using a magnetic field according to claim 1, wherein: the method for improving the arc extinguishing efficiency of the multi-cavity structure by using the magnetic field can be used for manufacturing the lightning protection device with the multi-cavity structure.
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| DE102014002902B4 (en) * | 2014-02-27 | 2019-08-01 | Schaltbau Gmbh | Extinguishing chamber for a contactor and a contactor for extinguishing electric arcs |
| CN107481823B (en) * | 2017-09-20 | 2023-08-01 | 广东电网有限责任公司湛江供电局 | Lightning-proof tripping self-arc-extinguishing parallel gap system for power distribution network |
| CN110098564A (en) * | 2019-04-22 | 2019-08-06 | 中国电力科学研究院有限公司 | A kind of band external series gap lightning arrester and lightning protection system |
| CN210693018U (en) * | 2019-09-16 | 2020-06-05 | 华格电子（昆山）有限公司 | Three-stage gas discharge tube capable of extinguishing arc |
| CN210779497U (en) * | 2019-12-10 | 2020-06-16 | 江苏赛福电气有限公司 | Multi-cavity arc blowing type lightning protection device |
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