Implementation mode of discharge electrode capable of discharging stably

Abstract

The invention provides an implementation mode of a discharge electrode capable of discharging stably. The implementation mode comprises the following steps: S1, constructing a power-frequency-free follow current lightning stroke limiter; s2, simulating a lightning stroke process of the non-power-frequency follow-current lightning stroke limiter; s3, obtaining corona discharge data; and S4, evaluating the shape stability of the discharge electrode of the non-power-frequency follow current lightning stroke limiter according to the discharge data. When the no-power-frequency follow-current lightning stroke limiter is designed, gap discharging is considered, the proper discharging electrode shape is selected, the stability of the discharging process is guaranteed, and therefore the line is better protected, and the problem that the operation safety of the power transmission line is affected due to breakdown between a wire and an insulator in a fault in the power transmission line can be solved.

Description

Technical Field

[0001] The present invention relates to the technical field of power distribution network transmission lines, and in particular to a method for realizing a discharge electrode capable of stable discharge. Background Art

[0002] In recent years, accidents such as line breakage, tripping, and insulator flashover have occurred frequently. As the length of insulated conductor lines increases, the number of such accidents has increased dramatically, and has become a major problem that seriously threatens the safe operation of distribution network circuits. At present, most 10kV / 35kV lines use gapless arresters to avoid lightning damage and protect the lines. Gapless zinc oxide arresters still have certain defects: (1) They must withstand power frequency voltage for a long time, which may cause aging of the zinc oxide valve plate, shorten the life of the arrester, and affect its protection performance; (2) If the soil resistivity is high and the line tower is poorly grounded, when overvoltage occurs, the arrester on the line cannot completely and effectively release the large current, which will form power frequency continuous current oscillation in the line, thereby causing the voltage on the line to rise, endangering safety. Therefore, a discharge electrode implementation method that can discharge stably is proposed to solve the above problems. Summary of the invention

[0003] In view of this, an object of the present invention is to provide a discharge electrode implementation method that can stably discharge, so as to at least solve the above problems.

[0004] The technical solution adopted by the present invention is as follows:

[0005] A method for realizing a discharge electrode capable of stable discharge includes the following steps:

[0006] S1. Construct a non-power frequency follow-on lightning limiter;

[0007] S2, simulate the lightning strike process without power frequency freewheeling lightning strike limiter;

[0008] S3, obtaining corona discharge data;

[0009] S4. Evaluate the shape stability of the discharge electrode of the non-power-frequency follow-current lightning stroke limiter based on the discharge data.

[0010] Further, in step S1, the non-power frequency follow-current lightning strike limiter includes a drainage device, a discharge gap plate, a discharge gap lower electrode, a power frequency current limiter, a grounding electrode plate, a supporting insulator, and a discharge gap upper electrode. The drainage device is used to guide lightning impulses, the discharge gap plate is used to allow current to pass through and release overvoltage, the discharge gap lower electrode is used to cooperate with the discharge gap plate to form the negative electrode part of the discharge gap, when the voltage difference reaches the breakdown voltage, the gap between the discharge gap lower electrode and the upper electrode will be broken down to form a conductive channel, the power frequency current limiter is used to limit the passage of power frequency current, the grounding electrode plate is used to guide the electric impulse current into the earth, the supporting insulator is used to support and fix the discharge gap plate and the grounding electrode plate, and the discharge gap upper electrode is used to cooperate with the discharge gap plate to form the positive electrode part of the discharge gap.

[0011] Furthermore, in step S2, the simulation of the lightning strike process of the non-power frequency freewheeling lightning strike limiter includes excitation, ionization, attachment, recombination, separation, diffusion and migration.

[0012] Furthermore, the excitation equation is expressed as:

[0013] A+e - →A * +e - (1)

[0014] A * →A+hv (2)

[0015] The ionization includes impact ionization and photoionization. The impact ionization equation is expressed as:

[0016] A+e - →A + +2e - (3)

[0017] The photoionization equation is expressed as:

[0018] A+hv→A + +e - (4)

[0019] The attachment equation is:

[0020] A+e - →A - (5)

[0021] The composite equation is:

[0022] e - +(XY) + →(XY) * →XY+hv (6)

[0023] Where (XY) +is the number of positive ions per unit volume, (XY) * is the number of composite ions formed by the combination of free electrons and positive ions per unit volume, (XY) is the number of stable molecules per unit volume after releasing photons;

[0024] The separation equation is:

[0025] A - +hv→A+e - (7)

[0026] Where e - represents the electron, A is the atom or molecule that collides with it, and A * is the excited atom or molecule, hv is the wavelength A photon with energy hv, where h is Planck's constant.

[0027] Furthermore, the specific formula of the diffusion is as follows:

[0028]

[0029] The diffusion coefficient D can be obtained from the kinetic theory of gas molecules: Where; λ is the mean free path, v r is the speed of thermal motion.

[0030] Furthermore, the migration is specifically as follows: by using fluid dynamics to represent the generation, movement and disappearance of electrons, positive and negative ions in space, using Poisson's equation to represent the influence of spatial charge density on the electric field, coupling the electric field and the fluid field, and obtaining a discharge simulation model:

[0031]

[0032] Among them, C e , C p , C n are the number densities of electrons, positive ions and negative ions respectively; t is time; α and η are the ionization coefficient and adsorption coefficient respectively; β np and β ep They are the recombination coefficients of positive ions and negative ions, and the recombination coefficients of electrons and positive ions, respectively. e , W p and W n are the drift rates of electrons, positive ions and negative ions respectively; D e , D p and D n are the diffusion coefficients of electrons, positive ions and negative ions respectively; S ph is the photoelectron generation rate, S0 is the background ionization rate; E is the electric field strength vector, V is the electric potential; ε0 is the vacuum dielectric constant; ε ris the relative dielectric constant; e is the electron charge; the subscripts e, p and n refer to electrons, positive ions and negative ions respectively; V a is the potential and i is the current when the pulse occurs.

[0033] Furthermore, in step S3, corona discharge data is obtained as follows:

[0034] The corona discharge data of 0-30000ns is obtained based on the discharge simulation model.

[0035] Furthermore, the electrode shapes of the discharge gap lower electrode and the discharge gap upper electrode are spherical or hemispherical.

[0036] Further, in step S4, the shape stability of the discharge electrode of the non-power frequency freewheeling lightning stroke limiter is evaluated based on the discharge data as follows:

[0037] Based on the corona discharge data obtained from 0-30000ns, the stability of the current pulse law of spherical and hemispherical electrodes was evaluated under the conditions of applying a 4.0kV voltage, the same sphere radius, and the same gap distance.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] When designing a non-power-frequency continuous current lightning stroke limiter, the present invention takes gap discharge into consideration and selects a suitable shape of discharge electrodes to ensure the stability of the discharge process, thereby better protecting the line, thereby solving the problem of the breakdown between the conductor and the insulator in a fault in the transmission line affecting the operation safety of the transmission line, and by changing the shape of the original discharge electrode from a sphere to a hemispherical shape, when lightning flows through the discharge gap again, the current is released more stably, thereby greatly improving the safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only preferred embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0041] Figure 1 This is the structure diagram of the non-power frequency follow-current lightning limiter;

[0042] Figure 2 It is the shape diagram of the upper electrode and the lower electrode of the discharge gap;

[0043] Figure 3 is the current pulse diagram of the hemispherical electrode;

[0044] Figure 4 This is the current pulse diagram of the spherical electrode.

[0045] Figure 1-Figure 2 Among them, 1. drainage device; 2. discharge gap plate; 3. discharge gap lower electrode; 4. power frequency current limiter; 5. grounding plate; 6. supporting insulator; 7. discharge gap upper electrode. DETAILED DESCRIPTION

[0046] The principles and features of the present invention are described below in conjunction with the accompanying drawings. The enumerated embodiments are only used to explain the present invention and are not used to limit the scope of the present invention.

[0047] Reference Figure 1 and Figure 2 The present invention provides a method for realizing a discharge electrode capable of stable discharge, comprising the following steps:

[0048] S1. Construct a non-power frequency follow-on lightning limiter;

[0049] S2, simulate the lightning strike process without power frequency freewheeling lightning strike limiter;

[0050] S3, obtaining corona discharge data;

[0051] S4. Evaluate the shape stability of the discharge electrode of the non-power-frequency follow-current lightning stroke limiter based on the discharge data.

[0052] In step S1, the non-power frequency follow-current lightning stroke limiter includes a drainage device 1, a discharge gap plate 2, a discharge gap lower electrode 3, a power frequency current limiter 4, a grounding plate 5, a supporting insulator 6, and a discharge gap upper electrode 7. The drainage device 1 is used to guide lightning impulses, the discharge gap plate 2 is used to allow current to pass through and release overvoltage, the discharge gap lower electrode 3 is used to cooperate with the discharge gap plate 2 to form the negative electrode part of the discharge gap, when the voltage difference reaches the breakdown voltage, the gap between the discharge gap lower electrode 3 and the upper electrode will be broken down to form a conductive channel, the power frequency current limiter 4 is used to limit the passage of power frequency current, the grounding plate 5 is used to guide the electric impulse current into the earth, the supporting insulator 6 is used to support and fix the discharge gap plate 2 and the grounding plate 5, and the discharge gap upper electrode 7 is used to cooperate with the discharge gap plate 2 to form the positive electrode part of the discharge gap.

[0053] In step S2, the lightning strike process of the non-power frequency freewheeling lightning strike limiter is simulated, including excitation, ionization, attachment, recombination, separation, diffusion and migration.

[0054] Excitation: Electrons that gain a certain amount of energy in an electric field, when colliding with gas atoms or molecules, the electrons on the outer orbits of the atoms or molecules gain energy and jump to higher energy orbits, and then return to a stable orbit and release light to release the remaining electrical energy.

[0055] The excitation equation is expressed as:

[0056] A+e - →A * +e - (1)

[0057] A * →A+hv (2)

[0058] Ionization: When the electrical energy obtained by atoms or molecules from the outside exceeds a certain value, such as above the ionization energy, the particles will release electrons and become positive ions. The ionization process in corona discharge is divided into impact ionization and photoionization.

[0059] The ionization includes impact ionization and photoionization. Impact ionization: If an electron has an ionization energy at least equivalent to that of an atom and collides with an atom or molecule, then the atom or molecule can be completely ionized in the collision. The impact ionization equation is expressed as:

[0060] A+e - →A + +2e - (3)

[0061] Photoionization: Through steps such as excitation, the generated light will lead to photoionization in the gas or photoemission on the electrode, which will increase the number of free electrons in the gas discharge gap, which plays a key role in some forms of gas discharge. When the total kinetic energy hv of the photon exceeds or is equal to the ionization ability of the gas atom, the photon can ionize the gas atom.

[0062] The photoionization equation is expressed as:

[0063] A+hv→A + +e - (4)

[0064] Attachment: If there are energy levels in the outermost layer of the gas that are not occupied by electrons (halogen gases, SF6, water vapor, O2 and other gases have these energy levels), then the low-speed electrons may occupy one of these energy levels when colliding with it. In this way, the atom will become a negative ion.

[0065] The attachment equation is:

[0066] A+e - →A - (5)

[0067] Recombination: Recombination occurs when electrons collide with positive ions. When the electrons enter a state of combination with positive ions, a neutral molecule is formed, and this molecule is likely to be in an excited state, so it releases photons to reach a stable state.

[0068] The composite equation is:

[0069] e - +(XY) + →(XY) * →XY+hv (6)

[0070] Where (XY) + is the number of positive ions per unit volume, (XY) * is the number of composite ions formed by the combination of free electrons and positive ions per unit volume, (XY) is the number of stable molecules per unit volume after releasing photons;

[0071] The light radiation obtained by recombination is called recombination luminescence. The recombination rate is proportional to the number of free electrons per unit volume and the number of positive ions per unit volume. Similar to the above process, in some gases containing negative ions, recombination will also occur when negative ions meet positive ions.

[0072] Separation: Separation occurs when a negative ion releases excess electrons and becomes a neutral molecule. This electron becomes a free electron again and can be accelerated by the electric field to collide and ionize other neutral particles.

[0073] The separation equation is:

[0074] A - +hv→A+e - (7)

[0075] Where e - represents the electron, A is the atom or molecule that collides with it, and A * is the excited atom or molecule, hv is the wavelength A photon with energy hv, where h is Planck's constant.

[0076] Diffusion: In the discharge space where there are many charged particles such as electrons and ions, when the particle density is unevenly distributed, the particles move from the denser areas to the less dense areas. This is called diffusion. The number of particles that diffuse in the X direction through the unit cross-sectional area per unit time can be calculated from the following formula:

[0077] The specific formula for the diffusion is as follows:

[0078]

[0079] The diffusion coefficient D can be obtained from the kinetic theory of gas molecules: Where; λ is the mean free path, v r is the speed of thermal motion.

[0080] Migration: When charged particles perform thermal motion in a gas, and are affected by the electric field force, the particles will move along the direction of the electric field, that is, directional motion is superimposed on the chaotic thermal motion.

[0081] Migration is specifically as follows: by using fluid dynamics to represent the generation, movement and disappearance of electrons, positive and negative ions in space, using Poisson's equation to represent the effect of spatial charge density on the electric field, coupling the electric field and fluid field, and obtaining a discharge simulation model:

[0082]

[0083] Among them, C e , C p , C n are the number densities of electrons, positive ions and negative ions respectively; t is time; α and η are the ionization coefficient and adsorption coefficient respectively; β np and β ep They are the recombination coefficients of positive ions and negative ions, and the recombination coefficients of electrons and positive ions, respectively. e , W p and W n are the drift rates of electrons, positive ions and negative ions respectively; D e , D p and D n are the diffusion coefficients of electrons, positive ions and negative ions respectively; S ph is the photoelectron generation rate, S0 is the background ionization rate; E is the electric field strength vector, V is the electric potential; ε0 is the vacuum dielectric constant; ε r is the relative dielectric constant; e is the electron charge; the subscripts e, p and n refer to electrons, positive ions and negative ions respectively; V a is the potential and i is the current when the pulse occurs.

[0084] In step S3, corona discharge data is obtained specifically as follows:

[0085] The corona discharge data of 0-30000ns is obtained based on the discharge simulation model.

[0086] The electrode shapes of the discharge gap lower electrode 3 and the discharge gap upper electrode 7 are spherical or hemispherical.

[0087] In step S4, the shape stability of the discharge electrode of the non-power frequency freewheeling lightning stroke limiter is evaluated based on the discharge data as follows:

[0088] Based on the corona discharge data obtained from 0-30000ns, the stability of the current pulse law of spherical and hemispherical electrodes was evaluated under the conditions of applying a 4.0kV voltage, the same sphere radius, and the same gap distance.

[0089] After the simulation test, the corona discharge data of 0-30000ns was obtained. Under the conditions of applying -4.0kV voltage, the same ball radius and the same gap distance, the current pulse of the hemispherical electrode is as follows: Figure 3 As shown, the current pulse of the ball electrode is Figure 4 In contrast, it can be found that the pulse current of the hemispherical electrode is more regular and the pulse frequency is higher, which means that the discharge of the hemispherical electrode is more stable.

[0090] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for realizing a discharge electrode capable of stable discharge, characterized in that: The following steps are involved: S1. Build a non-power frequency follow-on lightning limiter; S2, simulate the lightning strike process without power frequency freewheeling lightning strike limiter; S3, obtaining corona discharge data; S4. Evaluate the shape stability of the discharge electrode of the non-power-frequency follow-current lightning stroke limiter based on the discharge data.

2. The method for realizing a discharge electrode capable of stable discharge according to claim 1, characterized in that: In step S1, the non-power frequency follow-current lightning stroke limiter includes a drainage device, a discharge gap plate, a discharge gap lower electrode, a power frequency current limiter, a grounding electrode plate, a supporting insulator, and a discharge gap upper electrode. The drainage device is used to guide lightning impulses, the discharge gap plate is used to allow current to pass through and release overvoltage, the discharge gap lower electrode is used to cooperate with the discharge gap plate to form the negative electrode part of the discharge gap, when the voltage difference reaches the breakdown voltage, the gap between the discharge gap lower electrode and the upper electrode will be broken down to form a conductive channel, the power frequency current limiter is used to limit the passage of power frequency current, the grounding electrode plate is used to guide the electric impulse current into the earth, the supporting insulator is used to support and fix the discharge gap plate and the grounding electrode plate, and the discharge gap upper electrode is used to cooperate with the discharge gap plate to form the positive electrode part of the discharge gap.

3. The method for realizing a discharge electrode capable of stable discharge according to claim 1, characterized in that: In step S2, the lightning strike process of the non-power frequency freewheeling lightning strike limiter is simulated, including excitation, ionization, attachment, recombination, separation, diffusion and migration.

4. The method for realizing a discharge electrode capable of stable discharge according to claim 3, characterized in that: The excitation equation is expressed as: A+e - →A * +e - (1) A * →A+hv (2) The ionization includes impact ionization and photoionization. The impact ionization equation is expressed as: A+e - →A + +2e - (3) The photoionization equation is expressed as: A+hv→A + +e - (4) The attachment equation is: A+e - →A - (5) The composite equation is: e - +(XY) + →(XY) * →XY+hv (6) Where (XY) + is the number of positive ions per unit volume, (XY) * is the number of composite ions formed by the combination of free electrons and positive ions per unit volume, (XY) is the number of stable molecules per unit volume after releasing photons; The separation equation is: TO - +hv→A+e - (7) Where e - represents the electron, A is the atom or molecule that collides with it, and A * is the excited atom or molecule, hv is the wavelength A photon with energy hv, where h is Planck's constant.

5. The method for realizing a discharge electrode capable of stable discharge according to claim 4, characterized in that: The specific formula for the diffusion is as follows: The diffusion coefficient D can be obtained from the kinetic theory of gas molecules: in; λ is the mean free path, v r is the speed of thermal motion.

6. The method for realizing a discharge electrode capable of stable discharge according to claim 5, characterized in that: Migration is specifically as follows: by using fluid dynamics to represent the generation, movement and disappearance of electrons, positive and negative ions in space, using Poisson's equation to represent the effect of spatial charge density on the electric field, coupling the electric field and fluid field, and obtaining a discharge simulation model: Among them, C e , C p , C n are the number densities of electrons, positive ions and negative ions respectively; t is time; α and η are the ionization coefficient and adsorption coefficient respectively; β np and β ep They are the recombination coefficients of positive ions and negative ions, and the recombination coefficients of electrons and positive ions, respectively. e , W p and W n are the drift rates of electrons, positive ions and negative ions respectively; D e , D p and D n are the diffusion coefficients of electrons, positive ions and negative ions respectively; S ph is the photoelectron generation rate, S0 is the background ionization rate; E is the electric field strength vector, V is the electric potential; ε0 is the vacuum dielectric constant; ε r is the relative dielectric constant; e is the electron charge; the subscripts e, p and n refer to electrons, positive ions and negative ions respectively; V a is the potential and i is the current when the pulse occurs.

7. The method for realizing a discharge electrode capable of stable discharge according to claim 6, characterized in that: In step S3, corona discharge data is obtained specifically as follows: The corona discharge data of 0-30000ns is obtained based on the discharge simulation model.

8. The method for realizing a discharge electrode capable of stable discharge according to claim 7, characterized in that: The electrode shapes of the discharge gap lower electrode and the discharge gap upper electrode are spherical or hemispherical.

9. The method for realizing a discharge electrode capable of stable discharge according to claim 8, characterized in that: In step S4, the shape stability of the discharge electrode of the non-power frequency freewheeling lightning stroke limiter is evaluated based on the discharge data as follows: Based on the corona discharge data obtained from 0-30000ns, the stability of the current pulse law of spherical and hemispherical electrodes was evaluated under the conditions of applying a 4.0kV voltage, the same sphere radius, and the same gap distance.

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