CN102694352B - Method for improving insulator potential distribution in overhead power transmission line - Google Patents

Abstract

The invention discloses a method for improving the potential distribution of insulators in an overhead power transmission line, which includes: selecting a section with frequent flashovers based on historical data of the overhead power transmission line, and selecting towers, wires, organic composite insulators and tempered glass insulators with the largest usage string; use the finite element numerical calculation method, adopt the three-dimensional finite element model, and calculate the electric field and potential distribution parameters of the corresponding organic composite insulator and tempered glass insulator string in the ideal clean and dry environment and dirty and humid environment respectively, and carry out simulation analysis; based on the obtained The simulation analysis results call the corresponding improvement potential strategy. The method of the invention can realize the advantages of high power supply reliability of the grid, good safety and good economic benefits.

Description

Method for Improving Potential Distribution of Insulators in Overhead Transmission Lines

technical field

The invention relates to the technical field of maintenance and security of power grid transmission lines, in particular to a method for improving the potential distribution of insulators in overhead transmission lines, specifically to improving the potential distribution of organic composite insulators and tempered glass insulator strings in overhead transmission lines in dirty and humid environments method.

Background technique

In recent years, the transmission lines of various voltage levels in the power grid, especially the Northwest Power Grid, have repeatedly experienced insulator flashover tripping accidents, which have had a major impact on the reliability of the power supply of the power grid and caused great economic losses; according to the analysis of flashover accidents, the accumulation of insulator surface Pollution is one of the main causes of flashover, and the research on the potential distribution of insulators is an effective means to prevent flashover accidents of transmission lines.

In view of the randomness, variability, and multi-influencing factors of pollution, although many studies have been carried out on the potential distribution of towers, insulators, and pollution at home and abroad, it is still difficult to integrate conductors and towers into the simulation and guide pollution flashover protection. One subject, up to now, there is no complete and reasonable method to effectively deal with pollution flashover accidents of transmission line insulators, and there are major safety hazards in the operation of transmission lines.

Contents of the invention

In view of the above problems, the object of the present invention is to propose a method for improving the potential distribution of insulators in overhead transmission lines by how to effectively utilize historical data and how to consider the effects of conductors and towers on potential simulation analysis.

In order to achieve the above object, the technical solution adopted in the present invention is: a method for improving the potential distribution of insulators in overhead transmission lines, including:

a. Based on the historical data of the overhead transmission line, select the flashover frequent section of the overhead transmission line, and select the most frequently used section from the flashover frequent section: towers, conductors, and organic composite insulators and tempered string of glass insulators;

b. In a clean and dry ideal clean and dry environment, use the three-dimensional model as the finite element model, and incorporate the towers and wires selected in step a into the three-dimensional model, and set the artificial boundary through the zero-order asymptotic boundary condition to be infinite The range is truncated into a limited area, wherein: the size of the artificial boundary is based on the fact that the surrounding electric field of the composite insulator and the tempered glass insulator string hardly changes with the expansion of the field boundary, so that the finite element numerical calculation method is used: (1) The organic composite insulators selected in the simulation analysis step a: surface potential distribution along the leakage distance, surface potential distribution nephogram, surface electric field intensity distribution along the leakage distance, surface electric field intensity distribution nephogram, surface maximum electric field intensity with the pressure equalizing ring pipe diameter The law of the change, the law of the maximum electric field intensity on the surface of the grading ring with the diameter of the grading ring, and the relationship between the maximum value of the surface electric field and the diameter of the grading ring and the depth of the grading ring, and the average electric field intensity along the The distribution of the leakage distance; (2) and, for the tempered glass insulator string selected in the step a, the simulation analysis: when the tempered glass insulator string with different numbers of pieces is taken, the voltage bearing ratio near the high and low voltage sides The relationship with the number of pieces; and, when the tempered glass insulator strings with different numbers of pieces are taken, the potential distribution nephogram of the tempered glass insulator strings;

c. In an ideal dirty and humid environment covered with a uniform dirt layer and with the same degree of moisture everywhere, based on the finite element model adopted in step b and the artificial boundary set, further add a second to the finite element model A three-dimensional surface unit is used to simulate the ideal dirty and humid environment, wherein the two-dimensional surface unit is endowed with the conductivity of the dirty layer, and the physical thickness of the two-dimensional surface unit is ignored in the entire finite element model, thereby using the finite element Numerical calculation method: (1) Simulation analysis of the organic composite insulator selected in step a under different conductivity of the fouling layer: the relationship between the distribution of the surface potential along the leakage distance and the conductivity of the fouling layer, the normal component of the surface electric field intensity along the The relationship between the distribution of the leakage distance and the conductivity of the polluted layer, the relationship between the distribution of the tangential component of the surface electric field along the leakage distance and the conductivity of the polluted layer, the distribution cloud diagram of the surface electric field intensity when the conductivity of the polluted layer is different, and the surface The relationship between the maximum value of the electric field strength and its normal and tangential component maximum value and the conductivity of the dirt layer; (II) and, for the selected tempered glass insulator string of the step a, the simulation analysis: when taking different sheets When the number of toughened glass insulator strings is different, the relationship between the voltage bearing rate near the high and low voltage sides and the number of pieces and the conductivity of the dirty layer when the conductivity of the dirty layer is different; When glass insulator strings are used, the potential distribution cloud diagram of tempered glass insulator strings under different conductivity of the fouling layer;

d. Based on the simulation analysis results in the ideal clean and dry environment and the ideal dirty and humid environment obtained in steps b and c, call the corresponding potential improvement strategy.

Further, the finite element models in steps b and c all adopt the following subdivision method: firstly, the longitudinal interface of the composite insulator and the insulator string is subdivided, and then the center line of the composite insulator and the insulator string is used as the axis to surround the entire Insulators and insulator strings are divided into volumes.

Furthermore, the parameter setting of the tower in the model is based on the parameters in the actual line, and the value of the wire length in the model is based on reducing the influence of the two ends of the wire on the electric field around the insulator.

Further, the strategy for improving the potential in step d includes at least any of the following strategies:

Strategy 1: Based on historical overvoltage data, increase the number of insulators in the string of tempered glass insulators at towers with higher overvoltages;

Strategy 2: Add a silicone rubber climbing skirt to the porcelain body of the tempered glass insulator string;

Strategy 3: Apply RTV paint on strings of tempered glass insulators;

Strategy 4: Optimizing the shed structure of organic composite insulators;

Strategy 5: Optimizing the grading ring structure of organic composite insulators;

Strategy 6: Optimizing the hydrophobic properties of organic composite insulators.

Further, before invoking the improved potential strategy in step d, the results of the following additional simulation analysis are also synthesized:

1) Assuming that the electric field of the string of organic composite insulators and tempered glass insulators selected in step a is a purely resistive field under a dirty and humid state;

2) The surface potential of the organic composite insulator is simulated and analyzed using a discrete resistance model:

i) When the contamination is unevenly distributed along the axial direction of the insulator, set the conductivity of the contamination layer at a certain axial position h of the insulator to K _h , and use the conductivity K _hmax of the contamination layer at the highest point hmax of the axial position h to be the lowest point The ratio K _hmax : K _hmin of the conductivity K _hmin of the polluted layer at hmin represents the unevenness of the overall distribution of pollution along the axial direction of the insulator; when K _hmax ≥ K _hmin and K _hmax ≤ K _hmin , respectively simulate and analyze: a) Under different K _hmax : K _hmin ratios, the relationship between the composite insulator surface potential distribution and the leakage distance; b) under different K _hmax : K _hmin ratios, the ratio of the tangential component of the composite insulator surface electric field intensity and the average electric field intensity is the same as The relationship of the leakage distance; c) the relationship between the power surface density per unit area of any point on the dirty layer of the composite insulator and the leakage distance under different _Khmax : _Khmin ratios;

ii) When the pollution is unevenly distributed along the upper and lower surfaces of the insulator shed, set the conductivity of the dirt layer on the upper and lower surfaces of the shed to be K _T and _KB respectively, and use the ratio K _T : _KB to represent the pollution along the upper and lower surfaces of the insulator shed. Inhomogeneity of surface distribution; when K _T ≥ _KB and K _T ≤ _KB , respectively simulate and analyze: (1) the relationship between the surface potential distribution of the composite insulator and the leakage distance under different K _T : _KB ratios; (2) Under different K _T : _KB ratios, the ratio of the tangential component of the surface electric field intensity of the composite insulator to the average electric field intensity is related to the leakage distance; (3) under different K _T : _KB ratios, the composite insulator The relationship between the power surface density per unit area at any point on the polluted layer and the leakage distance;

3) Further, the series resistance model is used for simulation analysis of the tempered glass insulator string:

i) In the Cartesian coordinate system, divide the dirt layer on the surface of the single-piece toughened glass insulator of the toughened glass insulator string into several subsections along the leakage path, and assume that the conductivity of the dirt layer in each subsection is the same, thereby simplifying the simulation analysis. K _TS and K _BS represent the conductivity of the fouling layer on the upper and lower surfaces of the single-piece tempered glass insulator, respectively. When K _TS ≥ K _BS and K _TS ≤ K _BS , the simulation analysis: a) under different K _TS : K _BS ratios, The relationship between the surface potential distribution of the single-piece tempered glass insulator and the leakage distance; b) the distribution of the lower surface voltage bearing rate of the single-piece tempered glass insulator under different K _TS : K _BS ratios;

ii) Assuming that the leakage current is the resistive current that continuously distributes on the surface of the single-piece toughened glass insulator and flows through the dirty layer of the single-piece toughened glass insulator when there is no dry zone or local arc generation, further simulation analysis: different K _TS : Distribution of leakage current under K _BS ratio.

The technical solutions of the present invention will be described in further detail below through examples.

Detailed ways

The following description will be made in conjunction with preferred embodiments of the present invention. It should be understood that the preferred embodiments described here are only used to illustrate and explain the present invention, and are not intended to limit the present invention.

Embodiment one

According to an embodiment of the present invention, a method for improving the potential distribution of insulators in overhead transmission lines is provided, including:

a. Based on the historical data of overhead transmission lines, select the frequent flashover section of the overhead transmission line, and select the towers, wires, organic composite insulators and tempered glass insulator strings with the largest usage from the flashover frequent section;

b. In a clean and dry ideal clean and dry environment, use the three-dimensional model as the finite element model, and incorporate the towers and wires selected in step a into the three-dimensional model, and set the artificial boundary through the zero-order asymptotic boundary condition to be infinite The range is truncated into a limited area, wherein: the size of the artificial boundary is based on the fact that the surrounding electric field of the composite insulator and the tempered glass insulator string hardly changes with the expansion of the field boundary, so that the finite element numerical calculation method is used: (1) The organic composite insulators selected in the simulation analysis step a: surface potential distribution along the leakage distance, surface potential distribution nephogram, surface electric field intensity distribution along the leakage distance, surface electric field intensity distribution nephogram, surface maximum electric field intensity with the pressure equalizing ring pipe diameter The law of the change, the law of the maximum electric field intensity on the surface of the grading ring with the diameter of the grading ring, and the relationship between the maximum value of the surface electric field and the diameter of the grading ring and the depth of the grading ring, and the average electric field intensity along the The distribution of the leakage distance; (2) and, for the tempered glass insulator string selected in step a, the simulation analysis: when the tempered glass insulator string with different numbers of pieces is taken, the voltage bearing ratio near the high and low voltage sides is different from that of the pieces The relationship between the numbers; and, when different numbers of tempered glass insulator strings are taken, the potential distribution cloud map of the tempered glass insulator string;

c. In an ideal dirty and humid environment covered with a uniform dirt layer and with the same degree of moisture everywhere, based on the finite element model adopted in step b and the artificial boundary set, further adding a two-dimensional surface to the finite element model unit, in order to simulate the ideal dirty and humid environment, wherein, the two-dimensional surface unit is endowed with the conductivity of the foul layer, and the physical thickness of the two-dimensional surface unit is ignored in the whole finite element model, thereby using the finite element numerical calculation method: (I ) simulation analysis of the organic composite insulator selected in step a under different conductivity of the fouling layer: the relationship between the distribution of the surface potential along the leakage distance and the conductivity of the fouling layer, the distribution of the normal component of the surface electric field along the leakage distance is the same as that of the pollution The relationship between layer conductivity, the relationship between the distribution of the tangential component of the surface electric field intensity along the leakage distance and the conductivity of the polluted layer, the distribution cloud diagram of the surface electric field intensity when the conductivity of the polluted layer is different, and the maximum value of the surface electric field intensity and Its normal direction, the relationship between the maximum value of the tangential component and the conductivity of the fouling layer; (II) and, for the selected toughened glass insulator string of step a, the simulation analysis: when taking the toughened glass insulator string of different numbers of pieces, When the conductivity of different dirty layers is different, the relationship between the voltage bearing rate and the number of sheets and the conductivity of the dirty layer near the high and low voltage sides; When the rate is high, the potential distribution nephogram of the tempered glass insulator string;

d. Based on the simulation analysis results in the ideal clean and dry environment and the ideal dirty and humid environment obtained in steps b and c, call the corresponding potential improvement strategy.

Based on the above-mentioned embodiments recorded in steps a to d, those skilled in the art can fully understand the technical path of the present invention. Such a technical solution is essentially a simulation method. Based on the principle of simulation, naturally the more factors included more, the better the effect of the simulation, but for the present invention, due to the large number of parameters involved, in order to balance the amount of calculation and the technical effect, the basic feature of this embodiment is to effectively use historical data and representative data used in reality. meaningful towers, wires, organic composite insulators and tempered glass insulator strings, and innovatively incorporate towers and wires into the relevant finite element model, thus forming a novel, relatively complete, based on historical data and 3D finite element simulation In addition, with regard to the ideal dirty and humid environment in the above step c: since the dirty layer is a uniform dirty layer and the degree of moisture is the same everywhere, the dirty layer is a uniform conductive layer at this time, Different conductivity of the fouling layer corresponds to different ideal dirty and humid environments. Based on this, this embodiment additionally uses a two-dimensional surface unit to simulate the dirty layer on the surface of the insulator. The two-dimensional surface unit is given during the establishment process The conductance property of the wet dirt layer ignores the physical thickness in the entire finite element model, so that this embodiment not only takes the dirt layer into account in the finite element calculation but also avoids subdividing small-sized geometry.

The above-mentioned embodiment not only forms a simulation idea and technical characteristics different from the existing technology, but also finally forms a complete and organic technical solution through the connection of various steps for improving organic composite insulators in overhead transmission lines in dirty and humid environments. And the potential distribution of the tempered glass insulator string improves the safety of the transmission line.

Embodiment two

The difference from the above-mentioned embodiment is that in this embodiment, the finite element models in steps b and c of the above-mentioned embodiment 1 all adopt the following subdivision method: firstly, the composite insulator and the longitudinal interface of the insulator string are plane subdivided, and then Taking the composite insulator and the center line of the insulator string as the axis to surround the entire insulator and the insulator string for volume division. The inventors found that using the general method to subdivide an insulator not only takes a long time to subdivide, but also requires a large amount of calculation, and the error between the subdivided finite element model and the original geometric model is relatively large, but this embodiment can effectively reduce the The calculation amount of the simulation.

Embodiment three

Different from the above-mentioned embodiment, in this embodiment, the parameter setting of the tower in the model of the above-mentioned embodiment 1 is based on the parameters in the actual line, and the value of the wire length in the model is to reduce the electric field around the insulator at both ends of the wire. influence prevails. For those skilled in the art, the parameter setting principles of the components in the simulation are inclined to the actual parameters in reality, or to ideal modeling, and there is another tendency, which intends to combine the advantages of the first two tendencies. The purpose of the above parameter setting principles is to balance the parameters in practice and the parameters in ideal modeling, but as far as this embodiment is concerned, this embodiment is only intended to limit a specific parameter about the tower and wire in the model As for the setting principle, those skilled in the art can of course also base on the tendency of the aforementioned several parameter setting principles.

Embodiment Four

Different from the above-mentioned embodiment, in this embodiment, the strategy for improving the potential in step d of the above-mentioned embodiment 1 includes at least any of the following strategies:

Strategy 1: Based on historical overvoltage data, increase the number of insulators in the string of tempered glass insulators at towers with higher overvoltages;

Strategy 2: Add a silicone rubber climbing skirt to the porcelain body of the tempered glass insulator string;

Strategy 3: Apply RTV paint on strings of tempered glass insulators;

Strategy 4: Optimizing the shed structure of organic composite insulators;

Strategy 5: Optimizing the grading ring structure of organic composite insulators;

Strategy 6: Optimizing the hydrophobic properties of organic composite insulators.

As far as this embodiment is concerned, the above-mentioned strategies are aimed at organic composite insulators and also at tempered glass insulator strings, and some focus on further optimized design, while others focus on on-site work of technical support personnel. Which strategy to call depends on the simulation analysis results, because the simulation analysis involves both organic composite insulators and tempered glass insulator strings.

Embodiment five

Different from the above-mentioned embodiment, in this embodiment, before calling the improved potential strategy in step d in the above-mentioned embodiment 1, the results of the following additional simulation analysis are also integrated:

1) Assuming that the electric field of the string of organic composite insulators and tempered glass insulators selected in step a is purely resistive under the condition of pollution and humidity;

2) The surface potential of the organic composite insulator is simulated and analyzed using the discrete resistance model:

i) When the contamination is unevenly distributed along the axial direction of the insulator, set the conductivity of the contamination layer at a certain axial position h of the insulator to K _h , and use the conductivity K _hmax of the contamination layer at the highest point hmax of the axial position h to be the lowest point The ratio K _hmax : K _hmin of the conductivity K _hmin of the polluted layer at hmin represents the unevenness of the overall distribution of pollution along the axial direction of the insulator; when K _hmax ≥ K _hmin and K _hmax ≤ K _hmin , respectively simulate and analyze: a) Under different K _hmax : K _hmin ratios, the relationship between the composite insulator surface potential distribution and the leakage distance; b) under different K _hmax : K _hmin ratios, the ratio of the tangential component of the surface electric field intensity of the composite insulator to the average electric field intensity is the same as the leakage distance c) The relationship between the power surface density per unit area and the leakage distance at any point on the dirty layer of the composite insulator under different K _hmax : K _hmin ratios;

ii) When the pollution is unevenly distributed along the upper and lower surfaces of the insulator shed, set the conductivity of the dirt layer on the upper and lower surfaces of the shed to be K _T and _KB respectively, and use the ratio K _T : _KB to represent the pollution along the upper and lower surfaces of the insulator shed. Inhomogeneity of surface distribution; when K _T ≥ _KB and K _T ≤ _KB , respectively simulate and analyze: (1) The relationship between the surface potential distribution and leakage distance of composite insulators under different K _T : _KB ratios; (2 ) The relationship between the ratio of the tangential component of the electric field intensity on the surface of the composite insulator to the average electric field intensity and the leakage distance under different K _T : _KB ratios; ₍ 3) The unit area of any point on the dirty layer of the composite insulator under different K _T : KB ratios The relationship between the power surface density and the leakage distance;

3) Further, the series resistance model is used for simulation analysis of the tempered glass insulator string:

i) In the Cartesian coordinate system, divide the dirt layer on the surface of the single-piece toughened glass insulator of the toughened glass insulator string into several subsections along the leakage path, and assume that the conductivity of the dirt layer in each subsection is the same, thereby simplifying the simulation analysis. K _TS and K _BS represent the conductivity of the fouling layer on the upper and lower surfaces of the single-piece tempered glass insulator, respectively. When K _TS ≥ K _BS and K _TS ≤ K _BS , the simulation analysis: a) under different K _TS : K _BS ratios, The relationship between the surface potential distribution of a single-piece tempered glass insulator and the leakage distance; b) the distribution of the lower surface voltage bearing rate of a single-piece tempered glass insulator under different K _TS : K _BS ratios;

ii) Assuming that the leakage current is the resistive current that continuously distributes on the surface of the single-piece toughened glass insulator and flows through the dirty layer of the single-piece toughened glass insulator when there is no dry zone or local arc generation, further simulation analysis: different K _TS : Distribution of leakage current under K _BS ratio. As far as this example is concerned, there is no doubt that including the simulation analysis of the uneven pollution layer will help to get closer to the real misunderstood wet environment, and more accurately improve the organic compound in the overhead transmission line in the dirty and humid environment. Potential distribution of insulators and strings of tempered glass insulators.

To sum up, the methods for improving the potential distribution of insulators in overhead transmission lines according to the various embodiments of the present invention disclose methods based on historical data of overhead transmission lines for improving organic composite insulators and tempered glass insulators in overhead transmission lines in dirty and humid conditions. The potential distribution method of strings, through the simulation analysis of the potential and electric field intensity distribution of organic composite insulators and tempered glass insulator strings in overhead transmission lines under clean and dry, uniform dirt layer, and even uneven dirt layer, seeks a method The scheme for improving the antifouling property of the insulator; the method in the invention can be used in the optimal design of system equipment, and can ensure the safety of the power transmission system during normal operation, during failure and after failure.

Finally, it should be noted that: the above is only a preferred embodiment of the present invention, and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, for those skilled in the art, it still The technical solutions recorded in the foregoing embodiments may be modified, or some technical features thereof may be equivalently replaced. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (5)

1. improve the method for insulator Potential distribution in overhead transmission line, it is characterized in that, comprising:

A, historical data based on described overhead transmission line, choose the flashover section of taking place frequently of described overhead transmission line, and choose the maximum shaft tower of use amount, wire and organic composite insulator and toughened glass insulator string from this flashover section of taking place frequently;

B, under the desirable clean dried environment of clean dried, adopt threedimensional model as FEM (finite element) model, and include the tower and conductor selected by step a in described threedimensional model, and arranging Artificial Boundaries by infinitely great range cutoffs by zeroth order Asymptotic Boundary Conditions Technique is finite region, wherein: the size of Artificial Boundaries almost no longer changes with the expansion on field domain border with the surrounding electric field of described composite insulator and toughened glass insulator string and is as the criterion, thus utilize finite element numerical computational methods: the organic composite insulator selected by (1) simulation analysis step a: surface potential is along the distribution of leakage distance, surface potential cloud charts, surface field intensity is along the distribution of leakage distance, surface field intensity distributions cloud atlas, the rule of surface maximum field intensity grading ring caliber change, the rule of grading ring surface maximum field intensity grading ring caliber change, with surface field maximum of intensity and grading ring ring footpath and grading ring cover enter the relation between the degree of depth, and average field intensity is along the distribution of leakage distance, (2) and, for the toughened glass insulator string selected by described step a, simulation analysis: when getting the described toughened glass insulator string of different sheet number, is bearing the relation of rate and sheet number near the voltage of high and low pressure side, and, when getting the described toughened glass insulator string of different sheet number, the Potential distribution cloud atlas of toughened glass insulator string,

C, be coated with even pollution layer and under the filthy wet environment of the ideal that damp degree is identical everywhere, the described FEM (finite element) model adopted based on step b and the described Artificial Boundaries of setting, a two-dimensional surface unit is added further for described FEM (finite element) model, in order to simulate the filthy wet environment of described ideal, wherein, described two-dimensional surface unit is endowed pollution layer conductivity, the physical thickness of described two-dimensional surface unit is ignored in whole FEM (finite element) model, thus utilize finite element numerical computational methods: under the different pollution layer conductivity of (I) simulation analysis, organic composite insulator selected by step a: surface potential along the distribution of leakage distance with the relation between pollution layer conductivity, surface field intensity normal component along the distribution of leakage distance with the relation between pollution layer conductivity, surface field intensity tangential component along the distribution of leakage distance with the relation between pollution layer conductivity, the cloud charts of surface field intensity during different pollution layer conductivity, with maximum and the normal direction thereof of surface field intensity, tangential component maximum is with the relation between pollution layer conductivity, (II) and, for the toughened glass insulator string selected by described step a, simulation analysis: when getting the described toughened glass insulator string of different sheet number, when different pollution layer conductivity, bears the relation of rate and sheet number and pollution layer conductivity at the voltage near high and low pressure side, and, when getting the described toughened glass insulator string of different sheet number, when different pollution layer conductivity, the Potential distribution cloud atlas of toughened glass insulator string,

D, the simulation analysis result under the filthy wet environment of desirable clean dried environment and ideal based on step b, c gained, call and improve current potential strategy accordingly.

2. the method improving insulator Potential distribution in overhead transmission line according to claim 1, it is characterized in that, FEM (finite element) model in step b and c all adopts following subdivision method: first carry out face subdivision to the longitudinal interface of described composite insulator and insulator string, then with described composite insulator and insulator string center line for the axle collar carries out body subdivision around whole insulator, insulator string.

3. the method improving insulator Potential distribution in overhead transmission line according to claim 1, it is characterized in that, in model, the optimum configurations of shaft tower is as the criterion with parameter in actual track, and in model, the value of conductor length is as the criterion to reduce the impact of wire two ends on insulator surrounding electric field.

4. the method improving insulator Potential distribution in overhead transmission line according to claim 1, is characterized in that, described in steps d improves current potential strategy, at least comprises following arbitrary strategy:

Strategy 1: according to history overvoltage data, increases toughened glass insulator insulator string sheet number at the higher shaft tower place of overvoltage;

Strategy 2: set up silicon rubber creeping-increasing skirt on toughened glass insulator string porcelain body;

Strategy 3: brush RTV coating on toughened glass insulator string;

Strategy 4: optimize organic composite insulator umbrella skirt construction;

Strategy 5: optimize organic composite insulator Equalized voltage ring construction;

Strategy 6: optimize organic composite insulator hydrophobic character.

5. the method improving insulator Potential distribution in overhead transmission line according to claim 1, is characterized in that, before described in invocation step d improves current potential strategy, and the also result of comprehensive following extra simulation analysis:

1), under supposing filthy dampness, the described organic composite insulator chosen in step a and toughened glass insulator crosstalk field are purely resistive field;

2) discrete resistance model is adopted to carry out simulation analysis to the surface potential of described organic composite insulator:

I) when filth uneven distribution axial along insulator, if the pollution layer conductivity of a certain axial location h of insulator is K _h, and the pollution layer conductivity K at peak hmax place with axial location h _hmaxwith the pollution layer conductivity K at minimum point hmin place _hminratio K _hmax: K _hminrepresent the filthy degree of irregularity along the distribution of insulator axial integral; Work as K _hmax k _hminand K _hmax k _hmintime, simulation analysis respectively: a) different K _hmax: K _hminunder ratio, the relation of described surface of composite insulator Potential distribution and leakage distance; B) different K _hmax: K _hminunder ratio, the ratio of described surface of composite insulator electric field strength tangential component and average field intensity is with the relation of leakage distance; C) different K _hmax: K _hminthe power plane density of any point unit are and the relation of leakage distance under ratio, on described composite insulator pollution layer;

Ii) when filth is along insulator umbrella upper and lower surface uneven distribution, if the upper and lower surperficial pollution layer conductivity of full skirt is respectively K _t, K _b, and by the two ratio K _t: K _brepresent the filthy degree of irregularity along the distribution of insulator umbrella upper and lower surface; Work as K _t k _band K _t k _btime, simulation analysis respectively: (1) different K _t: K _bunder ratio, the relation of described surface of composite insulator Potential distribution and leakage distance; (2) different K _t: K _bunder ratio, the ratio of described surface of composite insulator electric field strength tangential component and average field intensity is with the relation of leakage distance; (3) different K _t: K _bthe power plane density of any point unit are and the relation of leakage distance under ratio, on described composite insulator pollution layer;

3) further, adopt series resistance model to carry out simulation analysis to described toughened glass insulator string:

I) in rectangular coordinate system, the strengthened glass insulation sub-surface pollution layer of described toughened glass insulator string is divided into several segment along leakage paths, and supposes that the pollution layer conductivity in each segment is identical, thus simplify simulation analysis, if K _tS, K _bSrepresent the upper and lower surperficial pollution layer conductivity of strengthened glass insulator respectively, work as K _tS k _bSand K _tS k _bStime, simulation analysis respectively: a) different K _tS: K _bSunder ratio, the relation of the distribution of described strengthened glass insulator surface potential and leakage distance; B) different K _tS: K _bSunder ratio, described strengthened glass insulator lower surface voltage bears the distribution of rate;

Ii) establish leakage current to be when there is no dry zone or local arc produces, in strengthened glass insulation sub-surface pollution layer continuous distribution, and flow through the current in resistance property of strengthened glass insulator pollution layer, further simulation analysis: different K _tS: K _bSunder ratio, the distribution of leakage current.