Simulation method of discharge injection in insulating medium considering deviation and bifurcation

Abstract

Disclosed is a discharge streamer simulation method that takes into account offset and bifurcation. In the method, an insulating medium is arranged in an electric field environment and the range of the number of discharge streamer bifurcation points and the range of the number of effective electron avalanches generated by each bifurcation in the insulating medium are measured. Control equations and boundary conditions for streamer simulation are constructed based on a fluid dynamics drift-diffusion model and a bipolar load sub-model. Model parameters corrected based on electron avalanche development probability theory are introduced in the process of solving the equations, and mathematical description and simulation calculation of streamer offset and bifurcation phenomena are realized. Finally, the electric field distribution and charge distribution accompanying the discharge streamer development process that takes into account offset and bifurcation can be obtained.

Description

Technical Field

[0001] The present invention belongs to the technical field of insulating medium streamer discharge, and in particular relates to an insulating medium discharge streamer simulation method considering offset and bifurcation. Background Art

[0002] As one of the most common solid-liquid insulation forms in power systems, the discharge characteristics and mechanisms of oil-paper insulation have attracted much attention, especially the mathematical description and simulation methods of discharge phenomena in oil-paper insulation have become a research hotspot. Simulation calculation has not only become an effective supplement to experimental methods, but also the only way to explore discharge characteristics and mechanisms in the absence of experimental conditions. However, the existing simulation models are difficult to reflect randomness and dispersion, resulting in the difficulty of simulating the offset and bifurcation of the discharge current.

[0003] The existing technology sets random disturbance points (position, number and size are all random) in the oil, so that the streamer will bifurcate and deviate after reaching the disturbance point. However, on the one hand, the introduction of random disturbance points will greatly increase the number of grid divisions, increase the amount of calculation and occupy computing resources; on the other hand, the random disturbance points reflect the macroscopic random characteristics, such as the presence of bubbles and impurities in the oil, oil flow disturbances, local uneven distribution, etc., and streamer bifurcation and deviation phenomena will also occur in pure isotropic oil. In addition, there is no mature theoretical support for the size range and density range of random disturbance points. Therefore, it is necessary to study the description method of streamer bifurcation and deviation driven by microscopic mechanisms based on the generation and development probability of microscopic electron avalanches.

[0004] The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known to a person of ordinary skill in the art. Summary of the invention

[0005] The existing streamer simulations cannot effectively and quickly describe the streamer deviation and bifurcation phenomena. The purpose of the present invention is to provide a simulation method for streamer discharge in insulating media, which can effectively and quickly describe the streamer bifurcation and deviation based on the electron avalanche development probability theory. In order to achieve the above purpose, the present invention provides the following technical solutions:

[0006] A method for simulating discharge current injection of an insulating medium considering deviation and bifurcation of the present invention comprises:

[0007] In the first step, the insulating medium is placed in an electric field environment and the number range of discharge current injection bifurcation points in the insulating medium is determined [N ps , N pb ] and the range of the number of effective electron avalanches generated by each bifurcation [N bs , N bb ], randomly select N from all simulation calculation time nodes bpoint∈[N ps , N pb ], marked as the fork moment, where N ps With N pb are the minimum and maximum number of discharge current injection bifurcation points, N bs With N bb are the minimum and maximum effective electron avalanche numbers, N bpoint is the number of randomly selected bifurcation points;

[0008] In the second step, a discharge injection simulation model in an insulating medium is constructed based on a fluid dynamics drift diffusion model and a bipolar charge carrier migration model, wherein the initial value a of the average molecular distance in the fluid dynamics drift diffusion model is 0 Set to a constant real number greater than zero, and start calculating at the specified simulation step length from time zero. If the calculation reaches the bifurcation moment, enter the third step and continue calculating after the average molecular distance value is updated. Otherwise, continue calculating using the original parameter value. The simulation ends after the specified simulation time.

[0009] The third step is to calculate the probability of bifurcation at each stream head at a certain bifurcation moment:

[0010]

[0011] Among them, i is the serial number parameter, n s is the total number of all flow branches at the current moment; P s-i is the probability of bifurcation at the head of the i-th stream; E smax-i is the maximum electric field intensity of the i-th streamer head; E c is the electric field strength threshold for the streamer to continue to develop, E smax-i >Ec streamers are developable streamers; η is the streamer development probability index;

[0012] The fourth step is to s-i The bifurcation position of the streamer is extracted. Only one bifurcation position is extracted at each bifurcation moment. The streamer extracted is called the streamer to be bifurcated. The bifurcation position is located at the point where the field strength at its head is the largest, recorded as (x 0 ,y 0 , z 0 ), x 0 is the X-axis coordinate of the bifurcation position, y 0 is the Y-axis coordinate of the bifurcation position, z 0 is the Z-axis coordinate of the bifurcation position;

[0013] The fifth step is to use the bifurcation position as the center of the circle and the flow head radius r s The radius is 1 to 5 times of the radius of the arc surface or arc of 180°. sis the distance between the position with the maximum net charge density and the position with the maximum electric field intensity. The arc surface or arc line is divided into equal grids or equal intervals. r points to be developed, and satisfy n r >(5×N bb ), n r is the number of points to be developed, and the probability of effective electron avalanche moving to each point to be developed is calculated:

[0014]

[0015] Among them, j is the serial number parameter, P b-j is the probability of effective electron avalanche moving to the jth point to be developed; φ smax is the potential at the bifurcation location, φ j is the potential at the jth point to be developed; η is the streamer development probability index; φ c Developing a potential difference threshold for efficient electron avalanche;

[0016] The sixth step is to b-j , from n r Randomly select N points to be developed branch ∈[N bs , N bb ] effective development points, N branch is the total number of effective development points, when N branch = 1 means that the streamer is only deflected but not bifurcated. 0 ,y 0 , z 0 ) and the selected point to be developed (x k ,y k , z k ) forms a vector pointing to the point to be developed, which is regarded as the development direction of the effective electron avalanche, x k is the X-axis coordinate of the kth effective development point, y k is the Y-axis coordinate of the kth effective development point, z k is the Z-axis coordinate of the kth effective development point, where k = 1, 2, ..., N branch ;

[0017] Step 7: Use the normal vector to be parallel to the direction of the flow to be bifurcated and pass through the point (x 0 ,y 0 , z 0 ) or a plane perpendicular to the direction of the streamer to be developed and passing through point (x 0 ,y 0 , z 0 ) is the boundary. On the side to be developed, calculate the distance d from a point (x, y, z) in the solution domain to the ray where each branch development direction is located. k (x, y, z):

[0018]

[0019] The starting point of the ray is (x 0 ,y 0 , z 0 ), let d k The minimum value among (x, y, z) is d min (x, y, z), then construct the correction coefficient k cor (x, y, z) is as follows:

[0020]

[0021] Among them, γ is the gradient parameter, which controls the changing speed of the correction coefficient;

[0022] Step 8: Correct the average molecular distance in the fluid dynamics drift-diffusion model within the solution domain on the side to be developed.

[0023]

[0024] Among them, a cor is the corrected average molecular distance, which is a function related to spatial position and time; m is the correction scaling factor, and satisfies 0<m<1; K cor It is k cor The normalized result of 0 is the initial value of the average molecular distance in the fluid dynamics drift diffusion model; ΔT s is the time interval between this bifurcation moment and the next bifurcation moment; t is the streamer development time measured from the start of this bifurcation; the average molecular distance of the discharge streamer simulation model in the second step is updated to this correction value, and return to the second step.

[0025] In the insulating medium discharge streamer simulation method considering offset and bifurcation, the positive polarity streamer development probability index is 2 to 3; the negative polarity streamer development probability index is 1.5 to 2.

[0026] In the insulating medium discharge current injection simulation method considering offset and bifurcation, the gradient parameter γ is greater than 1.

[0027] In the above-mentioned method for simulating discharge current injection of insulating medium considering offset and bifurcation, the effective electron avalanche development electric field threshold E c ≥0, effective electron avalanche development potential difference threshold φ c ≥0.

[0028] In the above technical scheme, the present invention provides a method for simulating discharge current flow of insulating media taking into account offset and bifurcation, which has the following beneficial effects: based on the probability of electron avalanche development, a simulation description of discharge channel offset and bifurcation is realized, which can be used to construct and solve a two-dimensional discharge model or a three-dimensional discharge model. The present invention is applicable to all alternating currents (power frequency, harmonics, square waves, etc.), direct currents (positive polarity, negative polarity), AC / DC composite electrical stresses, and pulse electrical stresses. It can be used not only in oil-paper insulation systems, but also in any liquid-solid two-phase insulation systems or liquid single-phase insulation systems, and only the corresponding parameters need to be set according to the dielectric properties. The discharge phenomenon that can be described is not limited to spatial streamers, but also surface streamers. The parameters that can be corrected by the present invention are not only limited to the average molecular distance, but can also be the ionized molecular density n. 0 , ionization energy coefficient γ e , collision ionization coefficient A t , Impact ionization index coefficient B t , can be one or more of the above parameters, the correction method remains unchanged, but the selected coefficient is positively correlated with the charge generation term, then m∈(-1,0), if negatively correlated, then m∈(0,1). The radius of the arc surface (or arc) is r s 1 to 5 times of , this range is only to ensure the calculation accuracy, of course, it can also exceed this range, as long as the radius of the arc surface (or arc line) is greater than 0. The solution model described in the second step is not limited to the fluid dynamics drift diffusion model and the bipolar load sub-model, but can also be other similar streamer solution models. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0030] Figure 1 It is a flow chart of the simulation method of the discharge current injection of the insulating medium in the present invention;

[0031] Figure 2 It is a schematic diagram of the simulation calculation process of discharge current injection deviation and bifurcation in the present invention;

[0032] Figure 3 The simulation result of the spatial electric field distribution associated with the streamer deviation bifurcation in the present invention;

[0033] Figure 4 This is the simulation result of the spatial charge distribution associated with the streamer offset bifurcation in the present invention. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0037] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0038] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0039] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0040] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0041] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings. A simulation method for streamer discharge of insulating medium considering offset and bifurcation includes:

[0042] A method for simulating discharge current injection of insulating medium considering deviation and bifurcation comprises the following steps:

[0043] In the first step, the insulating medium is placed in an electric field environment and the number range of discharge current injection bifurcation points in the insulating medium is determined [N ps , N pb ] and the range of the number of effective electron avalanches generated by each bifurcation [N bs , N bb ], randomly select N from all simulation calculation time nodes bpoint ∈[N ps , N pb ], marked as the fork moment,

[0044] In this embodiment, it is confirmed by high-speed camera observation that N ps =0,N pb =5,N bs =1,N bb =3, randomly selected N bpoint =2, the corresponding bifurcation times are t=0.5ns and t=6.4ns respectively;

[0045] In the second step, a discharge injection simulation model in an insulating medium is constructed based on a fluid dynamics drift diffusion model and a bipolar charge carrier migration model, wherein the initial value a of the average molecular distance in the fluid dynamics drift diffusion model is 0 Set to a constant real number greater than zero, and start calculating at the specified simulation step length from time zero. If the calculation reaches the bifurcation time, enter the third step and continue the calculation after the average molecular distance value is updated, otherwise continue the calculation using the original parameter value; the simulation calculation ends after the specified simulation time length; the simulation time step is set to 0.1ns, the simulation time length is set to 200ns, a 0Set to 0.3nm;

[0046] The third step is to calculate the probability of bifurcation of each stream head at t = 0.5 ns or t = 6.4 ns:

[0047]

[0048] Among them, i is the serial number parameter, n s is the total number of all flow branches at the current moment; P s-i is the probability of bifurcation at the head of the i-th stream; E smax-i is the maximum electric field intensity of the i-th streamer head; E c is the electric field strength threshold for the streamer to continue to develop, E smax-i >E c The streamer is a developable streamer; η is the streamer development probability index; in this embodiment, E c Take 10 6 V / m, η is 2,

[0049] The fourth step is to s-i The bifurcation position of the streamer is extracted. Only one bifurcation position is extracted at each bifurcation moment. The streamer extracted is called the streamer to be bifurcated. The bifurcation position is located at the point where the field strength at its head is the largest, recorded as (x 0 ,y 0 , z 0 ),

[0050] The fifth step is to use the bifurcation position as the center of the circle and the flow head radius r s The radius is 1 to 5 times of the radius of the arc surface or arc of 180°. s is the distance between the position with the maximum net charge density and the position with the maximum electric field intensity. The arc surface or arc line is divided into equal grids or equal intervals. r points to be developed, and satisfy n r >(5×N bb ), n r is the number of points to be developed, and the probability of effective electron avalanche moving to each point to be developed is calculated:

[0051]

[0052] Among them, j is the serial number parameter, P b-j is the probability of effective electron avalanche moving to the jth point to be developed; φ smax is the potential at the bifurcation location, φ j is the potential at the jth point to be developed; η is the streamer development probability index; φ c is the potential difference threshold for effective electron avalanche development; in this embodiment, φ c =0, nr = 20, 3 times r sMake an arc,

[0053] The sixth step is to b-j , randomly select N from nr points to be developed branch ∈[N bs , N bb ] effective development points, N branch is the total number of effective development points, when N branch = 1 means that the streamer is only deflected but not bifurcated. 0 ,y 0 , z 0 ) and the selected point to be developed (x k ,y k , z k ) forms a vector pointing to the point to be developed, which is regarded as the development direction of the effective electron avalanche, where k = 1, 2, ..., N branch In this embodiment, N randomly selected at two bifurcation moments branch Both are 2,

[0054] Step 7: Use the normal vector to be parallel to the direction of the flow to be bifurcated and pass through the point (x 0 ,y 0 , z 0 ) or a plane perpendicular to the direction of the streamer to be developed and passing through point (x 0 ,y 0 , z 0 ) is the boundary. On the side to be developed, calculate the distance d from a point (x, y, z) in the solution domain to the ray where each branch development direction is located. k (x, y, z):

[0055]

[0056] The starting point of the ray is (x 0 ,y 0 , z 0 ), let d k The minimum value among (x, y, z) is d min (x, y, z), then construct the correction coefficient k cor (x, y, z) is as follows:

[0057]

[0058] Wherein, γ is a gradient parameter, which controls the change speed of the correction coefficient; in this embodiment, γ is 3,

[0059] Step 8: Correct the average molecular distance in the fluid dynamics drift-diffusion model within the solution domain on the side to be developed.

[0060]

[0061] Among them, a cor is the corrected average molecular distance, which is a function related to spatial position and time; m is the correction scaling factor, and satisfies 0<m<1; K cor It is k cor The normalized result of 0 is the initial value of the average molecular distance in the fluid dynamics drift diffusion model; ΔT s is the time interval between this bifurcation moment and the next bifurcation moment; t is the streamer development time from the start of this bifurcation; the average molecular distance of the discharge streamer simulation model in the second step is updated to the current correction value, and return to the second step. In this embodiment, m is 0.8, ΔT s =(6.4ns-0.5ns)=5.9ns.

[0062] The implementation results are shown below:

[0063] In one embodiment, the applicant initially thought of setting a randomly distributed space charge initial condition in the solution space, which is physically meaningful because the space charge inside the medium is unevenly distributed under the action of external factors (such as ultraviolet rays). A Random uniform random function is set at the space charge initial condition, but it is found that the streamer does not bifurcate. The reason is that the electric field distortion caused by the uneven initial charge distribution gradually disappears after several time steps. In fact, the initial state of the space charge will change rapidly as the streamer develops.

[0064] Although the method of random charge distribution initial value failed, the applicant thought that if the set random space charge initial value is allowed to continue to act, would it cause bifurcation. So the applicant set a randomly distributed background charge (not an initial value) to simulate the random factors inherent in the liquid medium (such as impurities, bubbles, etc.). Under the action of the randomly distributed background charge, the applicant obtained less than ideal simulation results. The charge of the streamer was intermittently distributed and not continuous, and the formed electric field channel did not show obvious bifurcation. The reason for this is that the randomly distributed background charge does affect the electric field distortion and charge generation at the head of the streamer, but does not indicate the development direction for the new streamer, which leads to the streamer not bifurcation.

[0065] Through the above exploration, the applicant realized that in order to achieve streamer bifurcation, it is necessary to start from the microscopic electron avalanche development probability, build a development probability model in each direction, and provide power for the development of new streamers. Therefore, the technical solution described in the present invention is proposed. The simulation results of the spatial electric field distribution accompanied by streamer offset bifurcation are shown in Figure 3 The simulation results of space charge distribution associated with streamer deviation bifurcation are shown in Figure 4 .

[0066] The method proposed by the present invention has more theoretical significance, because the discharge itself is a probabilistic event, and both the macroscopic random disturbance factors and the microscopic random disturbance factors are reflected in the probability change, which is more in line with reality. However, the method of artificially set random disturbance points (areas) can only reflect the influence of macroscopic disturbances, and the large number of discrete random disturbances is difficult to directly describe using mathematical formulas. Moreover, the position, number, and size of the set random disturbance factors are all subject to human subjective will.

[0067] The method proposed in this invention has a smaller amount of calculation (shorter computing resources and time). In order to achieve a significant effect, the diameter of the disturbance area needs to be controlled within 1 to 10 μm, and the area density is about 10 11 m -3 A large number of disturbance area settings lead to an increase in the number of grids (computing nodes), which leads to an increase in the amount of calculation, and requires the use of high-performance servers for solving. The method proposed in the present invention can be solved using an ordinary computer.

[0068] Finally, it should be noted that the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making any creative work are within the scope of protection of the present application.

[0069] The above description is only by way of illustration of certain exemplary embodiments of the present invention. It is undoubted that those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A method for simulating discharge current injection of insulating medium considering offset and bifurcation, characterized in that: It includes the following steps: In the first step, the insulating medium is placed in an electric field environment and the number range of discharge current injection bifurcation points in the insulating medium is determined [N ps , N pb ] and the range of the number of effective electron avalanches generated by each bifurcation [N bs , N bb ], randomly select N from all simulation calculation time nodes bpoint ∈[N ps , N pb ], marked as the fork moment, where N ps With N pb are the minimum and maximum number of discharge current injection bifurcation points, N bs With N bb are the minimum and maximum effective electron avalanche numbers, N bpoint is the number of randomly selected bifurcation points; The second step is to build a discharge injection simulation model in the insulating medium based on the fluid dynamics drift diffusion model and the bipolar charge carrier migration model, wherein the initial value a0 of the average molecular distance in the fluid dynamics drift diffusion model is set to a constant real number greater than zero, and the calculation is performed according to the prescribed simulation step length from time zero. If the calculation reaches the bifurcation moment, the third step is entered to continue the calculation after the molecular average distance value is updated, otherwise the original parameter value is used to continue the calculation; the simulation calculation ends after the prescribed simulation time. The third step is to calculate the probability of bifurcation at each stream head at a certain bifurcation moment: Among them, i is the serial number parameter, n s is the total number of all flow branches at the current moment; P s-i is the probability of bifurcation at the head of the i-th stream; E smax-i is the maximum electric field intensity of the i-th streamer head; E c is the electric field strength threshold for the streamer to continue to develop, E smax-i >E c The streamer is a developable streamer; η is the streamer development probability index; The fourth step is to s-i Extract the streamer bifurcation position. Only one bifurcation position is extracted at each bifurcation moment. The extracted streamer is called the streamer to be bifurcated. The bifurcation position is located at the point where the field strength at its head is the largest, recorded as (x0, y0, z0), where x0 is the X-axis coordinate of the bifurcation position, y0 is the Y-axis coordinate of the bifurcation position, and z0 is the Z-axis coordinate of the bifurcation position. The fifth step is to use the bifurcation position as the center of the circle and the flow head radius r s The radius is 1 to 5 times of the radius of the arc surface or arc of 180°. s is the distance between the position with the maximum net charge density and the position with the maximum electric field intensity. The arc surface or arc line is divided into equal grids or equal intervals. r points to be developed, and satisfy n r >(5×N bb ), n r is the number of points to be developed, and the probability of effective electron avalanche moving to each point to be developed is calculated: Among them, j is the serial number parameter, P b-j is the probability of effective electron avalanche moving to the jth point to be developed; φ smax is the potential at the bifurcation location, φ j is the potential at the jth point to be developed; η is the streamer development probability index; φ c Developing a potential difference threshold for efficient electron avalanche; The sixth step is to b-j , from n r Randomly select N points to be developed branch ∈[N bs , N bb ] effective development points, N branch is the total number of effective development points, when N branch =1 means that the stream is only deflected but not bifurcated, connecting (x0, y0, z0) and the selected point to be developed (x k ,y k , z k ) forms a vector pointing to the point to be developed, which is regarded as the development direction of the effective electron avalanche, x k is the X-axis coordinate of the kth effective development point, y k is the Y-axis coordinate of the kth effective development point, z k is the Z-axis coordinate of the kth effective development point, where k = 1, 2, ..., N branch ; Step 7: Take the plane whose normal vector is parallel to the development direction of the stream to be bifurcated and passes through the point (x0, y0, z0) as the boundary or the straight line perpendicular to the development direction of the stream to be developed and passes through the point (x0, y0, z0) as the boundary, and calculate the distance d from a certain point (x, y, z) in the solution domain to the ray where each branch development direction is located on its side to be developed. k (x, y, z): The starting point of the ray is (x0, y0, z0), let d k The minimum value among (x, y, z) is d min (x, y, z), then construct the correction coefficient k cor (x, y, z) is as follows: Among them, γ is the gradient parameter, which controls the changing speed of the correction coefficient; Step 8: Correct the average molecular distance in the fluid dynamics drift-diffusion model within the solution domain on the side to be developed. Among them, a cor is the corrected average molecular distance, which is a function related to spatial position and time; m is the correction scaling factor and satisfies 0 <m<1;K cor It is k cor Normalized result of ΔT s is the time interval between this bifurcation and the next bifurcation; t is the flow development time measured from the start of this bifurcation; update the average distance of molecules in the second step to this correction value, and return to the second step.

2. The method for simulating discharge injection of insulating medium considering deviation and bifurcation according to claim 1, characterized in that: The probability index of positive streamer development is 2 to 3; the probability index of negative streamer development is 1.5 to 2.

3. The method for simulating discharge injection of insulating medium considering offset and bifurcation according to claim 1, characterized in that: The gradient parameter γ is greater than 1.

4. The method for simulating discharge injection of insulating medium considering offset and bifurcation according to claim 1, characterized in that: The electric field threshold of effective electron avalanche development E c ≥0, effective electron avalanche development potential difference threshold φ c ≥0.

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