Calculation Method, System and Storage Medium for Corona Onset Field Strength of Spacer Dampers for Bundled Conductors

Abstract

The present invention provides a method, system and storage medium for calculating the corona inception field strength of a spacer dampers for bundled conductors, comprising the following steps: obtaining the outer circumferential radius and height of the spacer dampers for bundled conductors, and obtaining the atmospheric pressure and humidity of the environment in which the spacer dampers for bundled conductors are applied; using the obtained outer circumferential radius and height of the spacer dampers for bundled conductors to calculate the three-dimensional space electric field distribution around the spacer dampers for bundled conductors; using the three-dimensional space electric field distribution around the spacer dampers for bundled conductors and the atmospheric pressure and humidity of the environment in which the spacer dampers for bundled conductors are applied to obtain the functional relationship expressions of each coefficient in the calculation model; substituting the functional relationship expressions of each coefficient into the calculation model; solving the calculation model to obtain the corona inception field strength of the spacer dampers for bundled conductors calculated. The present invention can predict the corona inception field strength of the spacer dampers for bundled conductors at different altitudes, temperatures and humidities.

Description

Technical Field

[0001] The invention belongs to the technical field of AC power transmission and transformation, and particularly relates to a calculation method, system and storage medium for the corona inception field strength of a two - split conductor spacer. Background Art

[0002] With the improvement of voltage levels, the increasingly severe corona discharge phenomenon in ultra - high - voltage and extra - high - voltage power transmission and transformation projects not only consumes electric energy and increases losses, but also generates audible corona noise and radio interference, affecting the ecological environment. As essential components in high - voltage power transmission and transformation projects, fittings such as grading rings and spacers often have a very high surface electric field strength due to their small radius of curvature. Once it exceeds the critical value, corona discharge will be formed, and the resulting electromagnetic environment problems have also received increasing attention. From on - site observations of corona discharge in ultra - high - voltage substations, it is found that the corona discharge phenomenon on the surface of bus spacers in the substation is the most serious. Therefore, in order to effectively suppress the corona discharge phenomenon on the surface of spacers, it is necessary to strictly control the magnitude of the corona inception field strength of the spacers.

[0003] Currently, the external characteristic method based on fitting experimental data and the semi - empirical method combining experimental research and theoretical research are the main methods for obtaining the corona inception field strength of charged conductors. Peek, based on a large amount of experimental data, first proposed an empirical formula applicable to the corona inception field strength of cylindrical conductors. Subsequently, some scholars proposed some modified empirical formulas for corona inception based on this formula. Whitehead, Stockmeyer et al. gave empirical formulas for the corona inception field strength of conductors under the action of positive and negative DC voltages. However, these empirical formulas lack sufficient accuracy and cannot obtain generally applicable research results, and cannot fundamentally solve the corona problem.

[0004] In recent years, starting from the basic physical process of corona discharge, domestic and foreign scholars have mostly used numerical calculation methods combined with gas discharge theory to study the corona inception voltage of charged conductors. From the published literature, the calculation model for the corona inception field strength of coaxial cylindrical conductors has been relatively mature. In addition, some scholars have also studied the calculation models for the corona inception field strength of some simple electrode shapes such as spherical electrodes and rod - plate electrodes. However, the calculation model applicable to the corona inception field strength of two - split conductor spacers has not been studied. Summary of the Invention

[0005] The purpose of the present invention is to solve the deficiencies existing in the above - mentioned background art, and provide a calculation method, system and storage medium for the corona inception field strength of a two - split conductor spacer, which can predict the corona inception field strength of a two - split conductor spacer at different altitudes, temperatures and humidities, and can provide a technical reference for the design of spacers in ultra - high - voltage / extra - high - voltage power transmission and transformation projects.

[0006] The technical solution adopted by the present invention is as follows: A calculation method for the corona inception field strength of a two - split conductor spacer, comprising the following steps:

[0007] S1. Obtain the outer circumferential radius and height of the spacer for two - split conductors to be calculated, and obtain the atmospheric pressure and humidity of the environment where the spacer for two - split conductors to be calculated is applied;

[0008] S2. Use the obtained outer circumferential radius and height of the spacer for two - split conductors to calculate the three - dimensional space electric field distribution around the spacer for two - split conductors to be calculated;

[0009] S3. Use the calculated three - dimensional space electric field distribution around the spacer for two - split conductors and the atmospheric pressure and humidity of the environment where the spacer for two - split conductors to be calculated is applied to obtain the functional relationship expression of each coefficient in the calculation model for the spacer for two - split conductors to be calculated; the functional relationship expression is used to characterize the mathematical relationship between each coefficient and the electric field strength at each point on the electron avalanche development path;

[0010] S4. Substitute the functional relationship expression of each coefficient and the electric field strength in the calculation model for the spacer for two - split conductors to be calculated into the calculation model; solve the calculation model, and take the electric field strength on the surface of the spacer for two - split conductors at the electron avalanche starting position calculated by the calculation model as the corona onset field strength.

[0011] In the above - mentioned technical solution, the calculation model is as follows:

[0012]

[0013] Among them, α(y) is the impact ionization coefficient, η(y) is the electron attachment coefficient, g(y) is the photon geometric absorption function area factor, γ ph is the surface photoelectron emission coefficient, N eph is the number of surface photoelectrons generated by photons reaching the surface of the spacer for two - split conductors, R is the outer circumferential radius of the spacer for two - split conductors; μ is the air photon absorption coefficient; y represents the position coordinate value of the space around the spacer for two - split conductors; y’ is a virtual integration variable; y i represents the ionization region boundary of the spacer for two - split conductors; both the impact ionization coefficient and the electron attachment coefficient are related to the space electric field strength. When the electric field strength at a certain point on the electron avalanche development path (along the y - axis direction) makes the impact ionization coefficient and the electron attachment coefficient equal, the y - coordinate corresponding to this electric field strength is yi.

[0014] When N eph takes a value of 1, the voltage acting on the impact ionization coefficient and the electron attachment coefficient is the corona onset voltage of the spacer for two - split conductors. Take the calculated corona onset voltage as the boundary condition to calculate the three - dimensional space electric field distribution around the spacer for two - split conductors, and the calculated electric field strength on the surface of the spacer for two - split conductors is the corona onset field strength.

[0015] In the above technical solution, the area factor g(y) of the spacer structure for the two-split conductor is divided into two components along the x-axis and the z-axis, expressed as:

[0016] g(y) = g x (y) × g z (y) (2)

[0017] In the formula, g x (y) and g z (y) are respectively the x-axis component and the z-axis component of the area factor of the photon geometric absorption function.

[0018]

[0019]

[0020] In the formula, θ is the angle formed by the photon emission path and the x-axis, is the angle formed by the photon emission path and the z-axis, λ1 and λ2 are the distances of photon transmission; R is the outer circumferential radius of the spacer for the two-split conductor, D is the height of the spacer for the two-split conductor; the area factor g(y) is a dimensionless parameter and is a function of the position y;

[0021] λ1 and λ2 are:

[0022]

[0023]

[0024] Substitute λ1 and λ2 into Equation (3) and Equation (4) respectively, then the x-axis component and the z-axis component of the area factor can be obtained. Substitute the calculation results of the x-axis component and the z-axis component of the area factor into Formula (2) to solve for the area factor g(y) of the photon geometric absorption function.

[0025] In the above technical solution, in the calculation model, the functional relationship expression between the electron impact ionization coefficient α(y) and the electric field strength is as follows:

[0026]

[0027]

[0028] α w (y) = N(3.536×10 17 (|E| / N) 2 -6.0×10 -2 (|E| / N) + 2.828×10 -21 ) (9)

[0029] In the formula, α w(y) is the numerical value of the component of the electron impact ionization coefficient affected by the partial pressure of water vapor in the atmosphere, α d (y) is the numerical value of the component of the electron impact ionization coefficient affected by the partial pressure of dry air in the atmosphere; P w is the partial pressure of water vapor in the atmosphere in the environment where the spacer of the bundled conductor is located, P d is the partial pressure of dry air in the atmosphere in the environment where the spacer of the bundled conductor is located, P = P w + P d ; P is the atmospheric pressure in the environment where the spacer of the bundled conductor is located; E is the electric field strength at each point in the development path of the electron avalanche, with the unit of V / m; N is the number density of gas molecules.

[0030] In the above technical solution, in the calculation model, the functional relationship expression between the electron attachment coefficient η(y) and the electric field strength is as follows:

[0031]

[0032]

[0033]

[0034] In the formula, η w (y) is the numerical value of the component of the electron attachment coefficient affected by the partial pressure of water vapor in the atmosphere, h d (y) is the numerical value of the component of the electron attachment coefficient affected by the partial pressure of dry air in the atmosphere.

[0035] In the above technical solution, in the calculation model, the calculation expression of the air photon absorption coefficient is as follows:

[0036]

[0037] In the formula, μ w is the numerical value of the component of the air photon absorption coefficient affected by the partial pressure of water vapor in the atmosphere, μ d is the numerical value of the component of the air photon absorption coefficient affected by the partial pressure of dry air in the atmosphere.

[0038] In the above technical solution, the construction process of the calculation model includes the following steps:

[0039] Define that the initial electron is located at the outermost circumferential edge of the spacer of the bundled conductor, with the coordinates (0, 0, 0), and it will develop along the direction of the power line towards the ground to form an initial electron avalanche;

[0040] When the initial electron avalanche develops to the coordinates (0, y, 0), the number of electrons N e (y) in the electron avalanche is:

[0041]

[0042] Wherein, α(y) is the electron impact ionization coefficient, and η(y) is the electron attachment coefficient;

[0043] The electrons generated at the coordinate y cause impact ionization at a distance of △y, and the number of photons generated during the impact ionization is:

[0044] △n ph (y) = α * (y)N e (y)△y (1.2)

[0045] Wherein, α * (y) is the air photon emission coefficient, which is approximately considered to be proportional to the electron impact ionization coefficient α(y); let the proportionality coefficient be k, then α * (y) = kα(y);

[0046] The number of photons reaching the surface of the spacer of the double-split conductor is:

[0047]

[0048] Among them, g(y)e -μy is the photon geometric absorption function, which represents the proportion of the photons reaching the surface of the spacer of the double-split conductor in the total number of photons generated at y, and is a function of the structure of the spacer of the double-split conductor, the distance to the surface of the spacer of the double-split conductor, and the air photon absorption coefficient μ; g(y) is the area factor of the photon geometric absorption function;

[0049] When the electron avalanche develops from the surface of the spacer of the double-split conductor to the boundary y i of the ionization region, since when y > y i , the effective ionization coefficient α(y) - η(y) < 0;

[0050] The number of surface photoelectrons generated by the photons reaching the surface of the spacer of the double-split conductor only considers the photons generated within the ionization region, as shown in Equation (1.4):

[0051]

[0052] Wherein, γ ph is the surface photoelectron emission coefficient, and the proportionality coefficient k is regarded as a constant and is included in γ ph , take γ ph = 0.001;

[0053] The photons reaching the surface of the spacer of the double-split conductor generate at least one photoelectron on the surface, and the generated photoelectrons form a new secondary electron avalanche, and the corona discharge on the surface of the spacer of the double-split conductor is self-sustaining; the formula for calculating the corona inception voltage of the spacer of the double-split conductor is derived as shown in Equation (1).

[0054] In the above technical solution, in step S2, the finite element method is used to calculate the three-dimensional space electric field distribution around the spacer of the two-conductor bundle; in step S4, the corona inception voltage is set as the boundary condition, and the finite element method is used to calculate the electric field strength on the surface of the spacer of the two-conductor bundle.

[0055] The present invention provides a calculation system for the corona inception field strength of a spacer of a two-conductor bundle, including a parameter acquisition module for the spacer of the two-conductor bundle, an environmental parameter acquisition module for the spacer of the two-conductor bundle, an electric field distribution calculation module for the spacer of the two-conductor bundle, an environmental coefficient calculation module, and a corona inception field strength calculation module;

[0056] The parameter acquisition module for the spacer of the two-conductor bundle is used to acquire the outer circumferential radius and height of the spacer of the two-conductor bundle to be calculated, and send the acquisition result to the electric field strength calculation module for the spacer of the two-conductor bundle;

[0057] The environmental parameter acquisition module for the spacer of the two-conductor bundle is used to acquire the atmospheric pressure and humidity of the environment in which the spacer of the two-conductor bundle to be calculated is applied, and send the acquisition result to the environmental coefficient calculation module;

[0058] The electric field distribution calculation module for the spacer of the two-conductor bundle is used to calculate the three-dimensional space electric field distribution around the spacer of the two-conductor bundle to be calculated by using the obtained outer circumferential radius and height of the spacer of the two-conductor bundle, and send the calculation result to the environmental coefficient calculation module;

[0059] The environmental coefficient calculation module is used to obtain the functional relationship expression of each coefficient in the calculation model for the spacer of the two-conductor bundle to be calculated by using the calculated three-dimensional space electric field distribution around the spacer of the two-conductor bundle and the atmospheric pressure and humidity of the environment in which the spacer of the two-conductor bundle to be calculated is applied, and send the acquisition result to the corona inception field strength calculation module;

[0060] The corona inception field strength calculation module is used to substitute the functional relationship expression of each coefficient in the calculation model for the spacer of the two-conductor bundle to be calculated into the calculation model; solve the calculation model, and take the electric field strength on the surface of the spacer of the two-conductor bundle at the electron avalanche initiation position obtained by the calculation as the corona inception field strength of the spacer of the two-conductor bundle to be calculated and output it.

[0061] The present invention provides a computer storage medium for a calculation method of the corona inception field strength of a spacer of a two-conductor bundle, including: instructions stored therein, wherein when the instructions are executed by one or more processors, the one or more processors execute the following methods including:

[0062] S1, acquire the outer circumferential radius and height of the spacer of the two-conductor bundle to be calculated, and acquire the atmospheric pressure and humidity of the environment in which the spacer of the two-conductor bundle to be calculated is applied;

[0063] S2. Using the outer circumferential radius and height of the obtained spacer for bundled two-conductor lines, calculate the three-dimensional space electric field distribution around the spacer for bundled two-conductor lines to be calculated.

[0064] S3. Using the three-dimensional space electric field distribution around the spacer for bundled two-conductor lines obtained by calculation and the atmospheric pressure and humidity of the environment where the spacer for bundled two-conductor lines to be calculated is applied, obtain the functional relationship expression of each coefficient in the calculation model for the spacer for bundled two-conductor lines to be calculated.

[0065] S4. Substitute the functional relationship expression of each coefficient in the calculation model for the spacer for bundled two-conductor lines to be calculated into the calculation model; solve the calculation model, and take the calculated electric field strength as the corona onset field strength of the spacer for bundled two-conductor lines to be calculated.

[0066] The beneficial effects of the present invention are as follows: Starting from the basic physical process of corona discharge, the present invention establishes a calculation method for the corona onset field strength of spacers for bundled two-conductor lines applicable to different voltage levels, altitudes, and atmospheric conditions. Previous studies obtained the corona onset field strength of spacers for bundled two-conductor lines through experimental methods, but this method lacks sufficient accuracy and cannot obtain generally applicable research results, and cannot fundamentally solve the corona problem. However, starting from the basic physical process of corona discharge, the present invention first proposes a calculation method for the corona onset field strength applicable to the structure of spacers for bundled two-conductor lines. Therefore, the size of the corona onset field strength of spacers for bundled two-conductor lines can be calculated to provide a technical reference for the spacer structure design of ultra / extra-high voltage power transmission and transformation projects. The present invention deduces the calculation model of the corona onset field strength of spacers for bundled two-conductor lines. By solving the calculation expressions of the photon geometric absorption function area factor, electron impact ionization coefficient, electron adsorption coefficient, and air photon absorption coefficient in the calculation model of the corona onset field strength of spacers for bundled two-conductor lines, a calculation method for the corona onset field strength of spacers for bundled two-conductor lines is established. On the one hand, the present invention first establishes an expression for the photon geometric absorption function area factor applicable to the structure of spacers for bundled two-conductor lines, which is different from the expression for the photon geometric absorption function area factor applicable to the coaxial cylindrical electrode structure established in existing research; on the other hand, the present invention gives the meanings and expressions of each physical quantity in the model, fully considering the environmental conditions where the spacers for bundled two-conductor lines are located, which are reflected in the expressions of the electron impact ionization coefficient, electron adsorption coefficient, and air photon absorption coefficient, that is, the environmental conditions where the spacers for bundled two-conductor lines are located affect the numerical values of the electron impact ionization coefficient, electron adsorption coefficient, and air photon absorption coefficient. This calculation method can calculate the corona onset field strength of spacers for bundled two-conductor lines of different models at different altitudes, temperatures, and humidities, and can provide a technical reference for the spacer structure design of ultra / extra-high voltage power transmission and transformation projects. Description of the Drawings

[0067] Figure 1It is a physical diagram of a typical spacer for a two - split conductor;

[0068] Figure 2 It is a schematic diagram of the corona inception of a spacer for a two - split conductor;

[0069] Figure 3 It is a schematic diagram of photons being emitted from any position in the electron avalanche and transmitted to the surface of the spacer for a two - split conductor;

[0070] Figure 4 It is a test layout diagram of the corona - starting voltage of a spacer for a two - split conductor;

[0071] Among them, 1 - spacer for a two - split conductor, 2 - split conductor, 3 - end shielding ring, 4 - power line, 5 - ground;

[0072] Figure 5 It is a finite - element simulation model of the corona - starting field strength of a spacer for a two - split conductor. Specific implementation mode

[0073] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments, which are convenient for clearly understanding the present invention, but they do not limit the present invention.

[0074] The present invention provides a calculation method for the corona - starting field strength of a spacer for a two - split conductor. The method includes the following steps:

[0075] S1, Obtain the outer - circumferential radius and height of the spacer for the two - split conductor to be calculated, and obtain the atmospheric pressure and humidity of the environment where the spacer for the two - split conductor to be calculated is applied;

[0076] S2, Use the obtained outer - circumferential radius and height of the spacer for the two - split conductor to calculate the three - dimensional space electric - field distribution around the spacer for the two - split conductor to be calculated;

[0077] S3, Use the calculated three - dimensional space electric - field distribution around the spacer for the two - split conductor and the atmospheric pressure and humidity of the environment where the spacer for the two - split conductor to be calculated is applied to obtain the functional - relationship expression of each coefficient in the calculation model for the spacer for the two - split conductor to be calculated;

[0078] S4, Substitute the functional - relationship expression of each coefficient in the calculation model for the spacer for the two - split conductor to be calculated into the calculation model; solve the calculation model, and take the electric - field strength on the surface of the spacer for the two - split conductor obtained by calculation as the corona - starting field strength of the spacer for the two - split conductor to be calculated.

[0079] The construction process of the calculation model adopted in the present invention and the derivation process of the calculation criterion for the corona - starting field strength of the spacer for the two - split conductor are as follows:

[0080] The physical diagram of a typical spacer for a two - split conductor is as Figure 1As shown. A voltage is continuously applied to the spacer for bundled conductors. When the electric field strength near the surface of the spacer for bundled conductors exceeds a certain value, the electron impact ionization coefficient α in the air will be greater than the electron attachment coefficient η, so that free electrons collide with air molecules, causing an initial electron avalanche. At the same time of collision ionization, the air molecules will reach an excited state and radiate photons to the surrounding. The radiated photons undergo a photoionization process with air molecules, and the photoelectrons further collide and ionize with air molecules to form a secondary electron avalanche, so that the corona can be self-sustained, as shown in the appendix Figure 2 as shown.

[0081] Assume that the "effective" initial electron is located at the outermost circumferential edge of the spacer for bundled conductors, with the coordinate of (0, 0, 0), and it will develop along the direction of the power line (the positive y-axis direction) towards the ground to form an initial electron avalanche. When the initial electron avalanche develops to the coordinate (0, y, 0), the number of electrons N e (y) is:

[0082]

[0083] In the formula, α(y) is the electron impact ionization coefficient, and η(y) is the electron attachment coefficient.

[0084] The electrons generated at the coordinate y cause collision ionization at a distance of △y, and the number of photons generated at the same time of collision ionization is:

[0085] △n ph (y) = α * (y)N e (y)△y (2)

[0086] In the formula, α * (y) is the air photon emission coefficient, and it is approximately considered to be proportional to the electron impact ionization coefficient α(y). Let the proportionality coefficient be k, then α * (y) = kα(y).

[0087] Since the photons generated by the initial electron avalanche are radiated evenly in all directions, only a part of them will face the surface of the spacer for bundled conductors. At the same time, during the radiation process of the photons towards the surface of the spacer for bundled conductors, a part of them will be absorbed by air molecules. Therefore, the number of photons reaching the surface of the spacer for bundled conductors is:

[0088]

[0089] Among them, g(y)e -μy is the photon geometric absorption function, which represents the proportion of the photons reaching the surface of the spacer for bundled conductors in the total number of photons generated at y, and it is a function of the structure of the spacer for bundled conductors, the distance to the surface of the spacer for bundled conductors, and the air photon absorption coefficient μ; g(y) is the photon geometric absorption function area factor.

[0090] The impact ionization coefficient and the electron attachment coefficient are both related to the spatial electric field strength. When the electric field strength at a certain point on the electron avalanche development path (along the y-axis direction) makes the impact ionization coefficient equal to the electron attachment coefficient, the y-coordinate corresponding to the electric field strength here is y i .

[0091] When the electron avalanche develops from the surface of the two-split conductor spacer to the boundary y i of the ionization region, since y > y i at this time, the effective ionization coefficient α(y) - η(y) < 0, and the electrons in the electron avalanche stop multiplying and gradually attach to the molecules to form negative ions. At this time, the number of photons generated is very small, and most of them are absorbed by air molecules and can be ignored. Therefore, when calculating the number of surface photoelectrons generated by the photons reaching the surface of the two-split conductor spacer, only the photons generated in the ionization region are considered, as shown in Equation (4).

[0092]

[0093] In the formula, γ ph is the surface photoelectron emission coefficient. Since the proportionality coefficient k is regarded as a constant, it is included in γ ph . Take γ ph = 0.001. If the photons reaching the surface of the two-split conductor spacer generate at least one photoelectron on the surface, then the generated photoelectrons can form a new secondary electron avalanche, and the corona can be self-sustaining. Therefore, the formula for calculating the corona inception voltage of the two-split conductor spacer is as shown in Equation (5).

[0094]

[0095] The three-dimensional space electric field distribution around the two-split conductor spacer is calculated by the finite element method, and the functional relationship between the electron impact ionization coefficient and the electron attachment coefficient is substituted into Equation (5). The electric field strength on the surface of the two-split conductor spacer at equilibrium in Equation (5) (the electric field strength at the initial position of the electron avalanche development path) is the corona inception field strength of the two-split conductor spacer.

[0096] The derivation process of the calculation expression of the area factor of the photon geometric absorption function in the corona inception field strength calculation criterion of the two-split conductor spacer is as follows:

[0097] The area factor of the two-split conductor spacer structure is divided into two components along the x-axis and along the z-axis (the x-axis direction is as shown in the appendix Figure 2 , and the z-axis direction is perpendicular to the x-y plane). The area factor of the photon geometric absorption function in the corona inception field strength calculation criterion of the two-split conductor spacer can be expressed as:

[0098] g(y) = g x(y)×g z (y) (6)

[0099] where g x (y) and g z (y) are the x-axis component and the z-axis component of the area factor of the photon geometric absorption function, respectively.

[0100]

[0101]

[0102] where θ is the angle in the x-axis direction, is the angle in the z-axis direction, λ1 and λ2 are the distances of photon transmission. R is the outer circumferential radius of the spacer of the bundled conductor, as Figure 2 shown. D is the height of the spacer of the bundled conductor, that is, the length along the z-axis direction. The photons at the onset of corona are emitted from any position in the electron avalanche and transmitted to the surface of the spacer of the bundled conductor. The relationship between the various parameters in Equations (7) and (8) is as Figure 3 shown. It can be seen from the component expressions that the area factor is a dimensionless parameter and is a function of the position y.

[0103] According to the cosine theorem, λ1 and λ2 in Equations (7) and (8) respectively need to satisfy:

[0104] (y + R) 2 + λ1 2 - R 2 = 2(y + R)λ1cosθ (9)

[0105]

[0106] Thus, λ1 and λ2 can be obtained as:

[0107]

[0108]

[0109] Substituting λ1 and λ2 into Equations (7) and (8) respectively, the g x (y) component and the g z (y)-axis component of the area factor can be obtained.

[0110] The derivation process of the calculation expressions of the electron impact ionization coefficient, the electron attachment coefficient, and the air photon absorption coefficient in the criterion for calculating the onset field strength of the spacer of the bundled conductor is as follows:

[0111] In order to apply the corona inception field strength calculation criterion for the spacer dampers of bundled conductors to different atmospheric conditions, it is necessary to establish the relationship between each coefficient in the criterion and the atmospheric conditions. Atmospheric conditions are usually characterized by pressure and temperature. Pressure and temperature mainly affect the corona discharge process through air density. Therefore, atmospheric conditions can be reflected by air density.

[0112] The relative air density can be expressed as:

[0113]

[0114] where P is the atmospheric pressure, in Pa; T is the thermodynamic temperature, in K; P0 is the reference atmospheric pressure, with a value of 1.01×10 5 Pa (1.01×10 5 Pa = 760 Torr); T0 is the reference thermodynamic temperature, with a value of 293 K.

[0115] The relative air density is only a concept of relative value, and the relationship between atmospheric conditions is determined by the gas law. The expression of the gas law is:

[0116] P = kNT (14)

[0117] where k is the Boltzmann constant. According to the gas law, the expression of relative air density can be derived, and the relationship between δ and N obtained is:

[0118] δ = N / N0 (15)

[0119] where N0 is the value of N when P and T are 1.01×10 5 Pa and 293 K respectively (N0≈2.5×10 25 m -3 ). Each coefficient in the corona inception field strength calculation criterion for the spacer dampers of bundled conductors is related to the relative air density δ. Through equation (15), the relationship between each coefficient and the gas molecular number density N can be established.

[0120] The calculation expression of the electron impact ionization coefficient is as follows:

[0121]

[0122]

[0123] α w (y) = N(3.536×10 17 (|E| / N) 2 -6.0×10 -2 (|E| / N)+2.828×10 -21 ) (18)

[0124] In the formula, α w (y) is the numerical value of the component of the electron impact ionization coefficient affected by the partial pressure of water vapor in the atmosphere, and α d (y) is the numerical value of the component of the electron impact ionization coefficient affected by the partial pressure of dry air in the atmosphere; P w is the partial pressure of water vapor in the atmosphere, and P d is the partial pressure of dry air in the atmosphere, and P = P w + P d ; E is the electric field strength at each point in the electron avalanche development path, with the unit of V / m; N is the number density of gas molecules.

[0125] The calculation expression of the electron attachment coefficient is as follows:

[0126]

[0127]

[0128]

[0129] In the formula, η w (y) is the numerical value of the component of the electron attachment coefficient affected by the partial pressure of water vapor in the atmosphere, and η d (y) is the numerical value of the component of the electron attachment coefficient affected by the partial pressure of dry air in the atmosphere.

[0130] The calculation expression of the air photon absorption coefficient is as follows:

[0131]

[0132] In the formula, μ w is the numerical value of the component of the air photon absorption coefficient affected by the partial pressure of water vapor in the atmosphere, and μ d is the numerical value of the component of the air photon absorption coefficient affected by the partial pressure of dry air in the atmosphere.

[0133] E in formulas (16)-(21) represents the value of the electric field strength at each point on the electron avalanche development path (along the y-axis direction) calculated using the finite element method.

[0134] E is the value of the electric field strength at each point on the electron avalanche development path (along the y-axis direction). Since the electric field strength values at each point on the electron avalanche development path are different, and both the electron impact ionization coefficient and the electron attachment coefficient are related to the electric field strength, the electron impact ionization coefficient and the electron attachment coefficient at each point on the electron avalanche development path are different.

[0135] The three-dimensional space electric field distribution E calculated by the finite element method is used to obtain the numerical values of the electron impact ionization coefficient and the electron adsorption coefficient at each point on the electron avalanche development path. After obtaining the numerical values of the impact ionization coefficient and the electron adsorption coefficient at each point, the numerical value of the area factor g(y) is calculated, and then the area factor g(y) and the numerical values of the impact ionization coefficient and the electron adsorption coefficient at each point are substituted into the calculation criterion. The E when Equation (5) holds is the onset voltage. Finally, the calculated onset voltage is used as the boundary condition, and the finite element method is used to calculate the electric field strength on the surface of the spacer of the bundled conductor (i.e., the electric field strength at the starting position of the calculation path).

[0136] The present invention provides a calculation system for the onset field strength of a spacer of a bundled conductor, including a parameter acquisition module for the spacer of the bundled conductor, an environmental parameter acquisition module for the spacer of the bundled conductor, an electric field distribution calculation module for the spacer of the bundled conductor, an environmental coefficient calculation module, and an onset field strength calculation module;

[0137] The parameter acquisition module for the spacer of the bundled conductor is used to acquire the outer circumferential radius and height of the spacer of the bundled conductor to be calculated, and send the acquisition result to the electric field strength calculation module for the spacer of the bundled conductor;

[0138] The environmental parameter acquisition module for the spacer of the bundled conductor is used to acquire the atmospheric pressure and humidity of the environment where the spacer of the bundled conductor to be calculated is applied, and send the acquisition result to the environmental coefficient calculation module;

[0139] The electric field distribution calculation module for the spacer of the bundled conductor is used to calculate the three-dimensional space electric field distribution around the spacer of the bundled conductor to be calculated by using the obtained outer circumferential radius and height of the spacer of the bundled conductor, and send the calculation result to the environmental coefficient calculation module;

[0140] The environmental coefficient calculation module is used to obtain the function relation expression between each coefficient and the electric field strength in the calculation model of the spacer of the bundled conductor to be calculated by using the calculated three-dimensional space electric field distribution around the spacer of the bundled conductor and the atmospheric pressure and humidity of the environment where the spacer of the bundled conductor to be calculated is applied, and send the acquisition result to the onset field strength calculation module;

[0141] The onset field strength calculation module is used to substitute the function relation expression between each coefficient and the electric field strength in the calculation model of the spacer of the bundled conductor to be calculated into the calculation model; solve the calculation model, and output the calculated electric field strength as the onset field strength of the spacer of the bundled conductor to be calculated.

[0142] The present invention provides a computer storage medium for a calculation method of the corona inception field strength of a two - split conductor spacer, including: instructions stored therein, wherein when the instructions are executed by one or more processors, the one or more processors are caused to execute the following method, including:

[0143] S1, obtain the outer circumferential radius and height of the two - split conductor spacer to be calculated, and obtain the atmospheric pressure and humidity of the environment in which the two - split conductor spacer to be calculated is applied;

[0144] S2, use the obtained outer circumferential radius and height of the two - split conductor spacer to calculate the three - dimensional space electric field distribution around the two - split conductor spacer to be calculated;

[0145] S3, use the calculated three - dimensional space electric field distribution around the two - split conductor spacer and the atmospheric pressure and humidity of the environment in which the two - split conductor spacer to be calculated is applied to obtain the functional relationship expression between each coefficient and the electric field strength in the calculation model of the two - split conductor spacer to be calculated;

[0146] S4, substitute the functional relationship expression between each coefficient and the electric field strength in the calculation model of the two - split conductor spacer to be calculated into the calculation model; solve the calculation model, and use the calculated electric field strength as the corona inception field strength of the two - split conductor spacer to be calculated.

[0147] The model of the two - split conductor spacer for a typical 500 kV extra - high - voltage AC substation is JS - 600K / 400. According to the specific dimensions of this two - split conductor spacer and based on the above - established calculation method of the corona inception field strength, a calculation program applicable to the corona inception field strength of the two - split conductor spacer is compiled. In order to verify the accuracy of the established calculation method of the corona inception field strength of the two - split conductor spacer, a corona inception voltage test of the two - split conductor spacer was carried out in the test hall of the UHV AC Test Base of China Electric Power Research Institute. The test hall is 86 m long, 60 m wide and 50 m high, and can hang test samples of UHV grade. The 1500 kV power frequency test power supply is used for the corona inception voltage test. The layout of the corona inception voltage simulation test of the two - split conductor spacer is as shown in the appendix Figure 4 as follows. Among them, the conductor radius is 25 mm, the conductor length is 6 m, and the height of the two - split conductor spacer from the ground H = 10 m.

[0148] The test was carried out in accordance with GB / T 2317.2-2008. During the test, the voltage applied to the spacer of the two-conductor bundle was gradually increased until the corona generation on the spacer of the two-conductor bundle was observed. Then it was maintained for 5 minutes, and this voltage was recorded as the corona inception voltage. Then the voltage applied to the spacer of the two-conductor bundle was gradually decreased until the corona on the spacer of the two-conductor bundle disappeared. Then it was maintained for 5 minutes, and this voltage was recorded as the corona extinction voltage. The above test was repeated three times, and the average values were taken as the corona inception voltage and the corona extinction voltage of the spacer of the two-conductor bundle respectively. At the same time, the environmental parameters such as air pressure, temperature, and humidity during the test were recorded. The environmental parameters during the test are shown in Table 1.

[0149] Using the finite element method, a three-dimensional finite element simulation model for the corona inception voltage test of the spacer of the two-conductor bundle was established, as shown in the appendix Figure 5 shown. The corona inception voltage was applied to the bundled conductors and the spacer. At this time, the point with the maximum electric field strength on the surface of the spacer of the two-conductor bundle was the corona inception point, and its field strength was the corona inception field strength. The magnitudes of the corona inception field strength are shown in Table 1. Using the calculation method of the corona inception field strength of the spacer of the two-conductor bundle established in this paper, with the same environmental parameters set as those in the corona inception voltage test, the calculated magnitudes of the corona inception field strength of the spacer of the two-conductor bundle are shown in Table 1.

[0150] Table 1 Test results and numerical calculation results of the corona inception field strength of the spacer of the two-conductor bundle

[0151]

[0152] As can be seen from Table 1, the relative error between the test results and the numerical calculation results of the corona inception field strength of the spacer of the two-conductor bundle is 3.43%, and the relative error is within ±5%. Therefore, it can be considered that the numerical calculation results are in good agreement with the test results.

[0153] The content not described in detail in this specification belongs to the prior art well-known to those skilled in the art.

Claims

1. A calculation method for the corona inception field strength of a spacer dampers for bundled conductors, characterized in that: It includes the following steps: S1. Obtain the outer circumferential radius and height of the spacer for the bundled two-conductor line to be calculated, and obtain the atmospheric pressure and humidity of the environment where the spacer for the bundled two-conductor line to be calculated is applied; S2. Use the obtained outer circumferential radius and height of the spacer for the bundled two-conductor line to calculate the three-dimensional space electric field distribution around the spacer for the bundled two-conductor line to be calculated; S3. Use the calculated three-dimensional space electric field distribution around the spacer for the bundled two-conductor line and the atmospheric pressure and humidity of the environment where the spacer for the bundled two-conductor line to be calculated is applied to obtain the functional relationship expression of each coefficient in the calculation model for the spacer for the bundled two-conductor line to be calculated; The functional relationship expression is used to characterize the mathematical relationship between each coefficient and the electric field strength at each point in the electron avalanche development path; S4. Substitute the functional relationship expression of each coefficient in the calculation model for the spacer for the bundled two-conductor line to be calculated into the calculation model; solve the calculation model, and take the electric field strength on the surface of the spacer for the bundled two-conductor line at the electron avalanche initiation position calculated by the calculation model as the corona inception field strength; The calculation model is as follows: where α(y) is the impact ionization coefficient, η(y) is the electron adsorption coefficient, g(y) is the photon geometric absorption function area factor, γ ph is the surface photoelectron emission coefficient, N eph is the number of surface photoelectrons generated by photons reaching the surface of the spacer of the bundled conductor; R is the outer circumferential radius of the spacer of the bundled conductor; μ is the air photon absorption coefficient; y represents the position coordinate value of the space around the spacer of the bundled conductor; y i represents the ionization region boundary of the spacer of the bundled conductor; y’ is the virtual integration variable; When N eph takes the value of 1, the voltage acting on the impact ionization coefficient and the electron attachment coefficient is the corona inception voltage of the spacer dampers for bundled conductors. The calculated corona inception voltage is used as the boundary condition to calculate the three-dimensional space electric field distribution around the spacer dampers for bundled conductors, and the electric field strength on the surface of the spacer dampers for bundled conductors obtained by calculation is the corona inception field strength; The area factor g(y) of the bundled two-conductor line spacer structure is divided into two components along the x-axis and the z-axis, expressed as: g(y) = g x (y) × g z (y) (2) where g x (y) and g z (y) are the x-axis component and z-axis component of the area factor of the photon geometric absorption function, respectively; In the formula, θ is the angle formed by the photon emission path and the x-axis, is the angle formed by the photon emission path and the z-axis, and λ1 and λ2 are the distances of photon transmission; R is the outer circumferential radius of the spacer of the two-split conductor, and D is the height of the spacer of the two-split conductor; the g(y) area factor is a dimensionless parameter and is a function of the position y; λ1 and λ2 are: Substitute λ1 and λ2 into Equation (3) and Equation (4) respectively, and the x-axis component and z-axis component of the area factor can be obtained. Substitute the calculation results of the x-axis component and z-axis component of the area factor into Equation (2) to solve for the area factor g(y) of the photon geometric absorption function; In the calculation model, the functional relationship expression of the electron impact ionization coefficient α(y) is as follows: α w (y) = N(3.536×10 17 (|E| / N) 2 -6.0×10 -2 (|E| / N)+2.828×10 -21 ) (9) where α w (y) is the numerical value of the component of the electron impact ionization coefficient affected by the partial pressure of water vapor in the atmosphere, and α d (y) is the numerical value of the component of the electron impact ionization coefficient affected by the partial pressure of dry air in the atmosphere; P w is the partial pressure of water vapor in the atmosphere in the environment where the spacer of the bundled conductor is located, and P d is the partial pressure of dry air in the atmosphere in the environment where the spacer of the bundled conductor is located, P = P w + P d ; P is the atmospheric pressure in the environment where the spacer of the bundled conductor is located; E is the electric field strength at each point in the electron avalanche development path, with the unit of V / m; N is the number density of gas molecules In the calculation model, the functional relationship expression of the electron adsorption coefficient η(y) is as follows: where η w (y) is the numerical value of the component of the electron adsorption coefficient affected by the partial pressure of water vapor in the atmosphere, and η d (y) is the numerical value of the component of the electron adsorption coefficient affected by the partial pressure of dry air in the atmosphere; In the calculation model, the calculation expression of the air photon absorption coefficient is as follows: where μ w is the numerical value of the component of the air photon absorption coefficient affected by the partial pressure of water vapor in the atmosphere, and μ d is the numerical value of the component of the air photon absorption coefficient affected by the partial pressure of dry air in the atmosphere.

2. The calculation method of the corona inception field strength of a two-split conductor spacer according to claim 1, characterized in that: The construction process of the calculation model includes the following steps: Define that the initial electron is located at the outermost circumferential edge of the spacer for the bundled two-conductor line, with coordinates (0, 0, 0), and it will develop along the direction of the power line towards the ground to form an initial electron avalanche; When the initial electron avalanche develops to the coordinate (0, y, 0), the number of electrons N e (y) is as follows: In the formula, α(y) is the electron impact ionization coefficient, and η(y) is the electron adsorption coefficient; The electrons generated at coordinate y cause impact ionization at a distance of Δy, and the number of photons generated during the impact ionization is: Δn ph (y) = α * (y)N e (y)Δy (1.2) where α * (y) is the air photon emission coefficient, which is approximately considered to be proportional to the electron impact ionization coefficient α(y); assuming the proportionality coefficient is k, then α * (y) = kα(y); The number of photons reaching the surface of the spacer for the bundled two-conductor line is: Among them, \(g(y)e\) -μy is the photon geometric absorption function, representing the proportion of photons reaching the surface of the spacer of the two-split conductor among the total number of photons generated at \(y\), which is a function of the structure of the spacer of the two-split conductor, the distance to the surface of the spacer of the two-split conductor, and the air photon absorption coefficient \(\mu\); \(g(y)\) is the area factor of the photon geometric absorption function; When the electron avalanche develops from the surface of the two-split conductor spacer to the boundary y of the ionization region i After that, since y > y i when, the effective ionization coefficient α(y) - η(y) < 0; The number of surface photoelectrons generated by the photons reaching the surface of the spacer for the bundled two-conductor line only considers the photons generated within the ionization region, as shown in Equation (1.4): where γ ph is the surface photoelectron emission coefficient, and the proportionality coefficient k is regarded as a constant and included in γ ph . Take γ ph = 0.001; The photons reaching the surface of the spacer for the bundled two-conductor line generate at least one photoelectron on the surface, and the generated photoelectrons form new secondary electron avalanches, and the corona discharge on the surface of the spacer for the bundled two-conductor line is self-sustaining; the formula for calculating the corona inception voltage of the spacer for the bundled two-conductor line is derived as shown in Equation (1).

3. The calculation method of the corona inception field strength of a two-split conductor spacer according to claim 1, characterized in that: In step S2, use the finite element method to calculate the three-dimensional space electric field distribution around the spacer for the bundled two-conductor line; in step S4, set the corona inception voltage as the boundary condition and use the finite element method to calculate the electric field strength on the surface of the spacer for the bundled two-conductor line.

4. A calculation system for the corona inception field strength of a two-split conductor spacer, characterized in that: For implementing the method according to any one of claims 1-3, it includes a split conductor spacer parameter acquisition module, a split conductor spacer environmental parameter acquisition module, a split conductor spacer electric field distribution calculation module, an environmental coefficient calculation module, and a corona inception field strength calculation module; The split conductor spacer parameter acquisition module is used to acquire the outer circumferential radius and height of the split conductor spacer to be calculated, and send the acquisition results to the split conductor spacer electric field strength calculation module; The split conductor spacer environmental parameter acquisition module is used to acquire the atmospheric pressure and humidity of the environment where the split conductor spacer to be calculated is applied, and send the acquisition results to the environmental coefficient calculation module; The split conductor spacer electric field distribution calculation module is used to calculate the three-dimensional space electric field distribution around the split conductor spacer to be calculated by using the obtained outer circumferential radius and height of the split conductor spacer, and send the calculation results to the environmental coefficient calculation module; The environmental coefficient calculation module is used to obtain the functional relationship expression of each coefficient of the split conductor spacer to be calculated in the calculation model by using the calculated three-dimensional space electric field distribution around the split conductor spacer and the atmospheric pressure and humidity of the environment where the split conductor spacer to be calculated is applied, and send the acquisition results to the corona inception field strength calculation module; The corona inception field strength calculation module is used to substitute the functional relationship expression of each coefficient of the split conductor spacer to be calculated in the calculation model into the calculation model; solve the calculation model, and take the electric field strength on the surface of the split conductor spacer at the electron avalanche initiation position obtained by calculation as the corona inception field strength of the split conductor spacer to be calculated and output it.

5. A computer-readable storage medium, comprising: Instructions stored therein, wherein when the instructions are executed by one or more processors, the one or more processors execute the method according to any one of claims 1-3.

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