阅读说明：本技术 确定不同温湿度条件下的导线直流起晕场强的方法及系统 (Method and system for determining direct-current corona-starting field intensity of lead under different temperature and humidity conditions ) 是由 徐吉来 路遥 刘震寰 张亮 万保权 张建功 干喆渊 刘兴发 谢辉春 张业茂 李妮 于 2021-07-22 设计创作，主要内容包括：本发明公开了一种确定不同温湿度条件下的导线直流起晕场强的方法和系统,包括：按照预设的电压步长施加正/负高压至目标导线,以使得目标导线起晕；获取在当前温湿度条件下施加至目标导线的不同正/负高压对应的地面电场强度数据和电晕电流数据；根据在当前温湿度条件下施加至所述目标导线的不同正/负高压对应的地面电场强度数据,确定所述目标导线在当前温湿度条件下的第一正/负起晕电压；根据在当前温湿度条件下施加至所述目标导线的不同正/负高压对应的电晕电流数据,确定所述目标导线在当前温湿度条件下的第二正/负起晕电压；根据所述第一正/负起晕电压和第二正/负起晕电压确定所述目标导线在当前温湿度条件下的正/负起晕电场强度。(The invention discloses a method and a system for determining direct-current corona field intensity of a lead under different temperature and humidity conditions, wherein the method comprises the following steps: applying positive/negative high voltage to a target wire according to a preset voltage step so as to enable the target wire to be corona; acquiring ground electric field intensity data and corona current data corresponding to different positive/negative high voltages applied to a target conductor under the current temperature and humidity condition; determining first positive/negative corona starting voltage of the target conductor under the current temperature and humidity condition according to ground electric field intensity data corresponding to different positive/negative high voltages applied to the target conductor under the current temperature and humidity condition; determining second positive/negative corona starting voltage of the target conductor under the current temperature and humidity condition according to corona current data corresponding to different positive/negative high voltages applied to the target conductor under the current temperature and humidity condition; and determining the positive/negative corona starting electric field intensity of the target conductor under the current temperature and humidity condition according to the first positive/negative corona starting voltage and the second positive/negative corona starting voltage.)

1. A method for determining direct-current corona field intensity of a wire under different temperature and humidity conditions is characterized by comprising the following steps:

applying positive/negative high voltage to a target wire according to a preset voltage step so as to enable the target wire to be corona;

acquiring ground electric field intensity data and corona current data corresponding to different positive/negative high voltages applied to the target conductor under the current temperature and humidity condition;

determining first positive/negative corona starting voltage of the target conductor under the current temperature and humidity condition according to ground electric field intensity data corresponding to different positive/negative high voltages applied to the target conductor under the current temperature and humidity condition;

determining second positive/negative corona starting voltage of the target conductor under the current temperature and humidity condition according to corona current data corresponding to different positive/negative high voltages applied to the target conductor under the current temperature and humidity condition;

and determining the positive/negative corona starting electric field intensity of the target conductor under the current temperature and humidity condition according to the first positive/negative corona starting voltage and the second positive/negative corona starting voltage.

2. The method of claim 1, further comprising:

adjusting the temperature and the humidity according to a preset adjusting strategy, acquiring positive/negative corona starting electric field intensities of the target conductor under different temperature and humidity conditions, and determining the incidence relation between the corona starting electric field intensity of the target conductor and the temperature and humidity according to the positive/negative corona starting electric field intensities of the target conductor under different temperature and humidity conditions.

3. The method of claim 1, wherein the method utilizes a positive/negative polarity high voltage generation module to generate positive/negative high voltage;

the positive/negative polarity high voltage generation module controls the amplitude of the voltage applied to the target conductor through the positive polarity high voltage control box and the negative polarity high voltage control box by using the positive/negative polarity high voltage generation module.

4. The method of claim 1, wherein the method utilizes a corona current acquisition module to acquire corona current data and utilizes a corona current data transmission module to photoelectrically convert the corona current data.

5. The method of claim 1, wherein the method comprises acquiring the ground electric field strength data by a direct current electric field acquisition module, and transmitting the ground electric field strength data by a direct current electric field data transmission module.

6. The method of claim 1, further comprising:

and measuring the temperature of the surface of the lead by using a remote infrared measuring instrument.

7. A system for determining direct current corona field intensity of a wire under different temperature and humidity conditions is characterized by comprising:

the voltage generating unit is used for applying positive/negative high voltage to a target wire according to a preset voltage step length so as to enable the target wire to be dizzy;

the data acquisition unit is used for acquiring ground electric field intensity data and corona current data corresponding to different positive/negative high voltages applied to the target conductor under the current temperature and humidity condition;

the first corona starting voltage determining unit is used for determining a first positive/negative corona starting voltage of the target conductor under the current temperature and humidity condition according to ground electric field intensity data corresponding to different positive/negative high voltages applied to the target conductor under the current temperature and humidity condition;

the second corona onset voltage determining unit is used for determining second positive/negative corona onset voltages of the target conductor under the current temperature and humidity condition according to corona current data corresponding to different positive/negative high voltages applied to the target conductor under the current temperature and humidity condition;

and the corona onset electric field strength determining unit is used for determining the positive/negative corona onset electric field strength of the target conductor under the current temperature and humidity condition according to the first positive/negative corona onset voltage and the second positive/negative corona onset voltage.

8. The system of claim 7, further comprising:

and the incidence relation determining unit is used for adjusting the temperature and the humidity according to a preset adjusting strategy, acquiring the positive/negative corona starting electric field strength of the target lead under different temperature and humidity conditions, and determining the incidence relation between the corona starting electric field strength of the target lead and the temperature and humidity according to the positive/negative corona starting electric field strength of the target lead under different temperature and humidity conditions.

9. The system of claim 7, wherein the voltage generation unit comprises:

the positive/negative polarity high voltage generation module is used for generating positive/negative high voltage;

wherein the positive/negative polarity high voltage generation module comprises: the positive polarity high voltage generator, the positive polarity high voltage control box, the negative polarity high voltage generator and the negative polarity high voltage control box; wherein the magnitude of the voltage applied to the target wire is controlled by a positive polarity high voltage control box and a negative polarity high voltage control box.

10. The system of claim 7, wherein the data acquisition unit comprises:

the corona current acquisition module is used for acquiring corona current data;

the corona current data transmission module is used for carrying out photoelectric conversion on corona current data;

the corona current acquisition module is used by connecting non-inductive resistors in parallel coaxially, realizes electrical isolation of a high-voltage end and a low-voltage end by using optical fibers, and acquires corona current data by using a high-speed acquisition card.

11. The system of claim 7, wherein the data acquisition unit further comprises:

the direct current electric field acquisition module is used for acquiring ground electric field intensity data;

the direct current electric field data transmission module is used for transmitting ground electric field intensity data;

wherein, direct current electric field collection module includes: a field grinding probe and a cover plate; and the direct current electric field data transmission module converts the electric signal measured by the field mill probe into a radio signal and transmits the ground electric field intensity data by radio.

12. The system according to claim 7, wherein in the voltage generation unit, the analog line where the target wire is located adopts a stranded wire or a thin copper wire, and the insulating rod for supporting the target wire adopts an epoxy resin material.

Technical Field

The invention relates to the technical field of calculating the field intensity of a corona-initiating electric field, in particular to a method and a system for determining the direct-current corona-initiating field intensity of a lead under different temperature and humidity conditions.

Background

The extra-high voltage is a power transmission technology with the voltage class of 1000 kilovolts of alternating current or more and +/-800 kilovolts of direct current or more, and has the technical advantages of large transmission capacity, long distance, high efficiency, low loss and the like. The extra-high voltage alternating current and direct current transmission project can generate electromagnetic environment problems around the line. One of key factors of the electromagnetic environment around the extra-high voltage direct current transmission line is a direct current synthetic field, the direct current synthetic field is effectively predicted and accurately measured, the electromagnetic environment problem around the direct current transmission line is controlled, the electromagnetic environment friendliness of residential areas along the power transmission and transformation project is guaranteed, and the method has important practical significance.

The direct current composite field is obviously influenced by the corona degree of the wire, and the corona degree of the wire is closely related to the wire characteristics such as the roughness degree of the wire, the applied voltage and the like and environmental factors such as temperature, humidity and the like. However, the influence mechanism of the synthetic electric field near the power transmission line due to environmental factors such as temperature and humidity is rarely studied, and the influence of environmental factors such as temperature and humidity on the corona degree of the wire needs to be studied. Because the environment where the actual line is located is greatly influenced by local climatic conditions, the line voltage is generally at rated voltage, and the voltage and the temperature and the humidity are uncontrollable, the influence of the temperature and the humidity on the corona field intensity of the lead is not favorably and quantitatively analyzed.

Therefore, a system for determining the corona onset electric field strength of the direct current lead under different temperature and humidity conditions needs to be established in a laboratory urgently, experiments of the corona onset degree of the lead under different temperature and humidity conditions are carried out, the corona onset degree of the lead under different temperature and humidity conditions is determined, and the correlation relationship between the direct current corona onset electric field strength and the temperature and humidity is researched.

Disclosure of Invention

The invention provides a method and a system for determining direct-current corona-starting field strengths of wires under different temperature and humidity conditions, and aims to solve the problem of how to accurately determine the direct-current corona-starting field strengths of the wires and further study the correlation between the corona-starting field strengths of the wires and the temperature and humidity.

In order to solve the above problem, according to an aspect of the present invention, there is provided a method for determining a direct current corona field strength of a wire under different temperature and humidity conditions, the method including:

applying positive/negative high voltage to a target wire according to a preset voltage step so as to enable the target wire to be corona;

acquiring ground electric field intensity data and corona current data corresponding to different positive/negative high voltages applied to the target conductor under the current temperature and humidity condition;

determining first positive/negative corona starting voltage of the target conductor under the current temperature and humidity condition according to ground electric field intensity data corresponding to different positive/negative high voltages applied to the target conductor under the current temperature and humidity condition;

determining second positive/negative corona starting voltage of the target conductor under the current temperature and humidity condition according to corona current data corresponding to different positive/negative high voltages applied to the target conductor under the current temperature and humidity condition;

and determining the positive/negative corona starting electric field intensity of the target conductor under the current temperature and humidity condition according to the first positive/negative corona starting voltage and the second positive/negative corona starting voltage.

Preferably, wherein the method further comprises:

adjusting the temperature and the humidity according to a preset adjusting strategy, acquiring positive/negative corona onset electric field strengths of the target conductor under different temperature and humidity conditions, and determining the incidence relation between the corona onset electric field strengths of the target conductor and the temperature and the humidity according to the positive/negative corona onset electric field strengths of the target conductor under different temperature and humidity conditions.

Preferably, wherein the method generates positive/negative high voltage using a positive/negative polarity high voltage generating module;

wherein the positive/negative polarity high voltage generation module comprises: the positive polarity high voltage generator, the positive polarity high voltage control box, the negative polarity high voltage generator and the negative polarity high voltage control box; wherein the magnitude of the voltage applied to the target wire is controlled by a positive polarity high voltage control box and a negative polarity high voltage control box.

Preferably, the method uses a corona current acquisition module to acquire corona current data, and uses a corona current data transmission module to perform photoelectric conversion on the corona current data;

the corona current acquisition module is used by connecting non-inductive resistors in parallel coaxially, realizes electrical isolation of a high-voltage end and a low-voltage end by using optical fibers, and acquires corona current data by using a high-speed acquisition card.

Preferably, the method uses a direct current electric field acquisition module to acquire ground electric field intensity data, and uses a direct current electric field data transmission module to transmit the ground electric field intensity data;

wherein, direct current electric field collection module includes: a field grinding probe and a cover plate; and the direct current electric field data transmission module converts the electric signal measured by the field mill probe into a radio signal and transmits the ground electric field intensity data by radio.

Preferably, the analog line where the target conductor is located is a stranded wire or a thin copper wire, and the insulating rod is made of epoxy resin material.

According to another aspect of the present invention, there is provided a system for determining a direct-current corona field strength of a wire under different temperature and humidity conditions, the system comprising:

the voltage generating unit is used for applying positive/negative high voltage to a target wire according to a preset voltage step length so as to enable the target wire to be dizzy;

the data acquisition unit is used for acquiring ground electric field intensity data and corona current data corresponding to different positive/negative high voltages applied to the target conductor under the current temperature and humidity condition;

the first corona starting voltage determining unit is used for determining a first positive/negative corona starting voltage of the target conductor under the current temperature and humidity condition according to ground electric field intensity data corresponding to different positive/negative high voltages applied to the target conductor under the current temperature and humidity condition;

the second corona onset voltage determining unit is used for determining second positive/negative corona onset voltages of the target conductor under the current temperature and humidity condition according to corona current data corresponding to different positive/negative high voltages applied to the target conductor under the current temperature and humidity condition;

and the corona onset electric field strength determining unit is used for determining the positive/negative corona onset electric field strength of the target conductor under the current temperature and humidity condition according to the first positive/negative corona onset voltage and the second positive/negative corona onset voltage.

Preferably, wherein the system further comprises:

and the incidence relation determining unit is used for adjusting the temperature and the humidity according to a preset adjusting strategy, acquiring the positive/negative corona starting electric field strength of the target lead under different temperature and humidity conditions, and determining the incidence relation between the corona starting electric field strength of the target lead and the temperature and humidity according to the positive/negative corona starting electric field strength of the target lead under different temperature and humidity conditions.

Preferably, the voltage generating unit includes:

the positive/negative polarity high voltage generation module is used for generating positive/negative high voltage;

wherein the positive/negative polarity high voltage generation module comprises: the positive polarity high voltage generator, the positive polarity high voltage control box, the negative polarity high voltage generator and the negative polarity high voltage control box; wherein the magnitude of the voltage applied to the target wire is controlled by a positive polarity high voltage control box and a negative polarity high voltage control box.

Preferably, the data acquiring unit includes:

the corona current acquisition module is used for acquiring corona current data;

the corona current data transmission module is used for carrying out photoelectric conversion on corona current data;

the corona current acquisition module adopts a non-inductive resistor for coaxial parallel connection, and simultaneously utilizes a high-speed acquisition card and optical fibers to realize electrical isolation of a high-voltage end and a low-voltage end so as to acquire corona current data.

Preferably, the data acquiring unit further includes:

the direct current electric field acquisition module is used for acquiring ground electric field intensity data;

the direct current electric field data transmission module is used for transmitting ground electric field intensity data;

wherein, direct current electric field collection module includes: a field grinding probe and a cover plate; and the direct current electric field data transmission module converts the electric signal measured by the field mill probe into a radio signal and transmits the ground electric field intensity data by radio.

Preferably, in the voltage generation unit, the analog line where the target conductor is located is a stranded wire or a thin copper wire, and the insulating rod is made of epoxy resin material.

The invention provides a method and a system for determining direct-current corona field intensity of a lead under different temperature and humidity conditions, wherein positive/negative high voltage is applied to a target lead according to a preset voltage step length so as to enable the target lead to corona; respectively determining a first positive/negative corona starting voltage and a second positive/negative corona starting voltage according to ground electric field intensity data and corona current data corresponding to different positive/negative high voltages applied to a target wire under the current temperature and humidity condition, and determining the positive/negative corona starting electric field intensity of the target wire under the current temperature and humidity condition according to the first positive/negative corona starting voltage and the second positive/negative corona starting voltage; the method can realize the calculation of the direct-current corona-starting field intensity of the wire under different temperature and humidity conditions, and can provide a test basis for deeply researching the mechanism of the direct-current corona-starting field intensity of the wire influenced by the temperature and humidity.

Drawings

A more complete understanding of exemplary embodiments of the present invention may be had by reference to the following drawings in which:

FIG. 1 is a flow chart of a method 100 for determining a wire DC corona field strength according to an embodiment of the present invention;

FIG. 2 is a logic diagram of a system for determining a DC corona field strength of a conductor according to an embodiment of the present invention;

fig. 3 is a schematic structural diagram of a system for determining a direct-current corona-starting field strength of a wire under different temperature and humidity conditions according to an embodiment of the present invention;

FIG. 4 is a schematic diagram of two-dimensional modeling of a field model using a finite element method and a subdivision result according to an embodiment of the present invention;

fig. 5 is a schematic structural diagram of a system 500 for determining a dc corona field strength of a wire according to an embodiment of the present invention.

Detailed Description

The exemplary embodiments of the present invention will now be described with reference to the accompanying drawings, however, the present invention may be embodied in many different forms and is not limited to the embodiments described herein, which are provided for complete and complete disclosure of the present invention and to fully convey the scope of the present invention to those skilled in the art. The terminology used in the exemplary embodiments illustrated in the accompanying drawings is not intended to be limiting of the invention. In the drawings, the same units/elements are denoted by the same reference numerals.

Unless otherwise defined, terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Further, it will be understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense.

Fig. 1 is a flow chart of a method 100 of determining a dc corona field strength of a wire according to an embodiment of the present invention. As shown in fig. 1, the method for determining the direct-current corona-starting field strength of the wire provided by the embodiment of the invention can provide a test basis for further researching a mechanism of the direct-current corona-starting field strength of the wire influenced by temperature and humidity. The method 100 for determining the direct current corona onset field strength of the conductor, provided by the embodiment of the invention, starts from step 101, and applies positive/negative high voltage to a target conductor according to preset voltage step length in step 101 so as to enable the target conductor to be corona.

Preferably, wherein the method generates positive/negative high voltage using a positive/negative polarity high voltage generating module;

wherein the positive/negative polarity high voltage generation module comprises: the positive polarity high voltage generator, the positive polarity high voltage control box, the negative polarity high voltage generator and the negative polarity high voltage control box; wherein the magnitude of the voltage applied to the target wire is controlled by a positive polarity high voltage control box and a negative polarity high voltage control box.

Preferably, the analog line where the target conductor is located is a stranded wire or a thin copper wire, and the insulating rod is made of epoxy resin material.

Referring to fig. 2 and 3, the present invention determines the dc corona field strength of the wire by the wire dc corona field strength system. Specifically, the wire direct current corona field strength system comprises: an insulating rod and a wire model which are arranged in the temperature and humidity test box body, a direct current electric field data and corona current data measuring end and a data receiving end. The direct current electric field data are transmitted to a local end through wireless communication, and the corona current data are connected to the local end through photoelectric conversion. The whole test is carried out in a temperature and humidity test box body, and the temperature and humidity in the test environment are controlled. The measuring end mainly performs high-voltage generation, high-voltage measurement, corona current measurement and collection, collection of direct current electric field data below the wire and measurement of the surface temperature of the wire, and the local end mainly performs high-voltage control, high-voltage data reception, corona current data reception, direct current electric field data reception and corresponding data processing.

Wherein, the measuring end includes: the device comprises a positive/negative polarity high voltage generation module, an analog line, an insulating rod, a corona current acquisition module, a direct current electric field acquisition module, a voltage data transmission module, a corona current data transmission module, a direct current electric field data transmission module and a lead surface temperature measurement module. The positive/negative polarity high voltage generation module is used for simulating voltage generation of high voltage direct current; the simulation circuit and the insulating rod are mainly used for applying voltage to the simulation circuit according to the step length until the surface of the wire is corona to generate corona current and space charge is generated in the space to form an ion flow field; the corona current acquisition module has the main function of measuring the corona current waveform after the conductor starts corona; the direct current electric field acquisition module is used for measuring and collecting a direct current electric field below the lead; the direct-current voltage data transmission module mainly transmits a voltage signal to a data receiving module at a local end through a voltage divider and other devices; the corona current data transmission module converts the electric signal into an optical signal through photoelectric conversion and transmits the optical signal to a local end; the direct current electric field data transmission module is mainly used for transmitting the measured direct current electric field data to a local terminal through wireless communication; the lead surface temperature measuring module mainly comprises a remote infrared measuring instrument and a bracket and is used for measuring the lead surface temperature condition.

In the invention, the positive/negative polarity high-voltage generation module generates positive/negative polarity high-voltage direct-current voltage in a simulation mode according to preset voltage step length, the generated voltage is applied to the lead until the surface of the lead is corona to generate corona current, and space charge is generated in space to form an ion flow field.

In the present invention, the positive/negative polarity high voltage generating module includes: the positive polarity high voltage generator, the positive polarity high voltage control box, the negative polarity high voltage generator, the negative polarity high voltage control box. The positive and negative polarity high voltage control boxes can control the amplitude of the applied voltage. In the analog circuit and the insulating rod, the analog circuit can adopt an actual stranded wire or a thin copper wire; the insulating rod can be made of epoxy resin materials and plays a role in supporting and insulating the ground.

In step 102, ground electric field intensity data and corona current data corresponding to different positive/negative high voltages applied to the target conductor under the current temperature and humidity condition are acquired.

Preferably, the method uses a corona current acquisition module to acquire corona current data, and uses a corona current data transmission module to perform photoelectric conversion on the corona current data;

the corona current acquisition module is used by connecting non-inductive resistors in parallel coaxially, realizes electrical isolation of a high-voltage end and a low-voltage end by using optical fibers, and acquires corona current data by using a high-speed acquisition card.

Preferably, the method uses a direct current electric field acquisition module to acquire ground electric field intensity data, and uses a direct current electric field data transmission module to transmit the ground electric field intensity data;

wherein, direct current electric field collection module includes: a field grinding probe and a cover plate; and the direct current electric field data transmission module converts the electric signal measured by the field mill probe into a radio signal and transmits the ground electric field intensity data by radio.

With reference to fig. 2 and 3, in the present invention, after the wire is corona started, the corona current collecting module is used to obtain corona current waveform data, and the corona current data transmitting module is used to convert the electrical signal into an optical signal through photoelectric conversion and transmit the optical signal to the local terminal. The corona current acquisition module mainly adopts non-inductive resistors to be coaxially connected in parallel for use, high-precision measurement of a wide frequency band is met, electrical isolation of a high-voltage end and a low-voltage end is achieved through optical fibers, and meanwhile, acquisition work of corona current is finally achieved through a high-speed acquisition card. The corona current data transmission module realizes high and low potential electrical isolation and finally transmits the isolation to a data comprehensive processing module in a computer mainly through photoelectric transmission and photoelectric reception.

From the beginning of pressurization, the direct current electric field below the conducting wire is measured and collected by the direct current electric field acquisition module to obtain ground electric field intensity data, and the measured direct current electric field data is transmitted to the local end by the direct current electric field data transmission module through wireless communication. The direct current electric field acquisition module mainly comprises a field grinding probe and a cover plate and is used for simulating direct current electric field data measurement under a lead wire. And the direct current electric field data transmission module converts the electric signal measured by the field mill probe into a radio signal, transmits the signal to the data receiving module by radio, converts the signal into the electric signal and performs further processing and analysis.

In step 103, a first positive/negative corona start voltage of the target conductor under the current temperature and humidity condition is determined according to ground electric field intensity data corresponding to different positive/negative high voltages applied to the target conductor under the current temperature and humidity condition.

In step 104, according to corona current data corresponding to different positive/negative high voltages applied to the target conductor under the current temperature and humidity condition, a second positive/negative corona starting voltage of the target conductor under the current temperature and humidity condition is determined.

In step 105, determining the positive/negative corona starting electric field intensity of the target conductor under the current temperature and humidity condition according to the first positive/negative corona starting voltage and the second positive/negative corona starting voltage.

Referring to fig. 2 and 3, in the present invention, a dc voltage data transmission module is used to transmit a voltage signal to a data receiving module of a local terminal through a voltage divider or the like; and measuring the surface temperature condition of the lead by using a remote infrared measuring instrument and a bracket of the lead surface temperature measuring module.

In the present invention, the local end includes: the device comprises a data receiving module and a data comprehensive processing module. The data receiving module mainly comprises three parts of voltage data receiving, corona current data receiving and direct current electric field data receiving. The voltage receiving device measures the applied high voltage value through a voltage divider and other devices, and can change the applied voltage value through a positive polarity high voltage control box and a negative polarity high voltage control box; the corona current data receiving module transmits the photoelectric converted signal to the data comprehensive processing module; the direct current electric field data receiving module is used for receiving wireless signals transmitted by the measuring end, converting the wireless signals into electric signals and transmitting the electric signals to the data comprehensive processing module; the data comprehensive processing module mainly has two functions, namely, recovering the obtained corona current signal into a current waveform, and recovering the obtained direct current electric field data electric signal into direct current electric field data according to time step and further processing the direct current electric field data electric signal to obtain the relevant characteristics of the data. The data comprehensive processing module has a good human-computer interaction interface.

In the invention, according to the climate environment of the actual line, the line conductor to be measured is selected, and for the relation between the corona onset electric field strength and the temperature, under the condition of ensuring certain humidity (65%), the temperature is controlled to be-20-50 ℃ respectively, the step length is 5 ℃, and the temperature is kept under each temperature condition respectively; for the relation between the intensity of the corona-initiating electric field and the humidity, the humidity is controlled from 50-80% under a certain temperature (20 ℃), the step length is 5%, and the humidity is respectively kept at each humidity.

After a certain temperature and humidity condition is determined, firstly, under the temperature and humidity condition, positive/negative high voltage is applied according to a certain step length, the ground electric field intensity, the wire surface temperature and the corona current waveform are recorded through the direct current electric field data transmission module and the corona current data transmission module, and after corona sound and the corona current waveform appear, upward pressurization is continued until corona is severe. Then, according to the relation curve of the ground electric field intensity and the applied voltage, a first positive/negative corona starting voltage of the wire under the temperature and humidity condition is obtained by adopting a tangent method. Then, according to the voltage when the corona current appears, a second positive/negative corona starting voltage of the wire under the condition of the temperature and the humidity is determined. And finally, calculating the corona onset voltage according to the obtained first positive/negative corona onset voltage and the second positive/negative corona onset voltage by weighting values of 0.5 and 0.5, modeling a field by using a finite element method, and solving a finite element equation to obtain the positive/negative corona onset electric field intensity of the wire under the temperature and humidity condition.

The method for solving the field intensity of the corona starting electric field by using the finite element method comprises the following steps:

and (4) carrying out model building on the field and carrying out subdivision processing, wherein the model can adopt a two-dimensional model as shown in figure 4.

The mathematical model of the field is the following boundary value problem:

wherein u is the field potential, f is the charge density in the field, a is the air dielectric constant, b, c are constants,normal gradient, Γ, for a class II boundary₁Is a type of boundary condition, gamma_2,3The boundary conditions are two or three types, and the boundary in the field domain is one type of boundary condition, namely the potential value is known. By interpolating basis functions M_nAn approximation function of the construct u is

For the Poisson equation (1), a group of weight functions M identical to the basis functions is set by using weak solution uniqueness of the Poisson equation and a Green formula under the first class of boundary conditions₁,M₂,…,Mn_eAnd obtaining a Galerkin finite element discrete equation:

apply Green's theorem to the above formula, and bring into the boundary conditions:

and (3) moving the term without unknown number u to the right side of the equation, and substituting the linear combination of the basis functions into the equation to obtain:

it can be seen that the above formula is in u₁,u₂,…,u_neIs an algebraic equation of a variable, which can be expressed as

Wherein the content of the first and second substances,

in the formula K_m，n、R_mAll are integral terms, and the interpolation function and parameters are known quantities and can be obtained by methods such as numerical integration and the like, so that the equation (3) can be dispersed into an equation

[K][u]＝[R] (8)

In addition, the conditional equations for a class of boundaries need to be rewritten, the known boundary node voltages are brought into the equations, and the point equation coefficient matrix is changed as follows:

K_k,k＝1

R_i＝R_i-K_i,ku_0,k(i＝1,2,...,n)

R_k＝u_0,k (9)

K_k,j＝0(i＝1,2,...,n)

K_i,k＝0(i＝1,2,...,n)

then, after the potential values of each point in the field are obtained, the following can be taken:

the maximum electric field intensity amplitude of the surface of the wire can be obtained. Since the wire can be regarded as a nominal field when just starting corona, the maximum electric field intensity value of the surface of the wire can be calculated according to the corona starting voltage obtained by the integration of the first corona starting voltage and the second corona starting voltage applied to the surface of the wire, namely the wire corona starting electric field intensity value.

Preferably, wherein the method further comprises:

adjusting the temperature and the humidity according to a preset adjusting strategy, acquiring positive/negative corona onset electric field strengths of the target conductor under different temperature and humidity conditions, and determining the incidence relation between the corona onset electric field strengths of the target conductor and the temperature and the humidity according to the positive/negative corona onset electric field strengths of the target conductor under different temperature and humidity conditions.

According to the method, the temperature/humidity is increased according to the step length, the step of obtaining the positive/negative corona starting electric field strength under a certain temperature and humidity condition is repeated, the positive/negative corona starting electric field strength value of the wire under different temperatures/humidities is obtained, a relation graph between the positive/negative corona starting electric field strength value of the wire and the temperature/humidity is drawn, and the direct-current corona starting electric field strength of the wire under different temperature and humidity conditions is finally determined.

Compared with the prior art, the invention has the following advantages due to the adoption of the technical scheme: 1. the temperature and humidity test box can ensure the stability and controllability of a test environment, and a remote infrared measuring instrument is used for measuring the surface temperature of the lead, so that the influence relation between the direct-current corona field intensity of the lead and the temperature and humidity can be accurately and efficiently researched; 2. the local end of the measurement system can control the measurement time step, monitor the measurement data in real time and obtain the data characteristics, and can master the characteristics of the measurement result in real time, thereby ensuring the controllability of the system; 3. the measurement corona current of adopting photoelectricity transmission and photoelectricity receipt can realize broadband, high accuracy measurement, can solve the electric isolation problem of high, low potential simultaneously.

The method for determining the direct-current corona-starting field intensity of the wire under different temperature and humidity conditions can be stably operated in a laboratory, and provides a test basis for deeply researching the mechanism of the direct-current corona-starting field intensity of the wire influenced by the temperature and humidity.

Fig. 5 is a schematic structural diagram of a system 500 for determining a dc corona field strength of a wire according to an embodiment of the present invention. As shown in fig. 5, a system 500 for determining a direct-current corona-starting field strength of a wire according to an embodiment of the present invention includes: a voltage generation unit 501, a data acquisition unit 502, a first corona onset voltage determination unit 503, a second corona onset voltage determination unit 504, and a corona onset electric field strength determination unit 505.

Preferably, the voltage generating unit 501 is configured to apply positive/negative high voltages to a target wire according to preset voltage steps so as to cause the target wire to corona.

Preferably, the voltage generating unit 501 comprises:

the positive/negative polarity high voltage generation module is used for generating positive/negative high voltage;

wherein the positive/negative polarity high voltage generation module comprises: the positive polarity high voltage generator, the positive polarity high voltage control box, the negative polarity high voltage generator and the negative polarity high voltage control box; wherein the magnitude of the voltage applied to the target wire is controlled by a positive polarity high voltage control box and a negative polarity high voltage control box.

Preferably, the data acquiring unit 502 is configured to acquire ground electric field intensity data and corona current data corresponding to different positive/negative high voltages applied to the target conductor under the current temperature and humidity condition.

Preferably, the data acquiring unit 502 includes:

the corona current acquisition module is used for acquiring corona current data;

the corona current data transmission module is used for carrying out photoelectric conversion on corona current data;

the corona current acquisition module is used by connecting non-inductive resistors in parallel coaxially, realizes electrical isolation of a high-voltage end and a low-voltage end by using optical fibers, and acquires corona current data by using a high-speed acquisition card.

Preferably, the data acquiring unit 502 further includes:

the direct current electric field acquisition module is used for acquiring ground electric field intensity data;

the direct current electric field data transmission module is used for transmitting ground electric field intensity data;

wherein, direct current electric field collection module includes: a field grinding probe and a cover plate; and the direct current electric field data transmission module converts the electric signal measured by the field mill probe into a radio signal and transmits the ground electric field intensity data by radio.

Preferably, the first corona onset voltage determining unit 503 is configured to determine a first positive/negative corona onset voltage of the target conductor under the current temperature and humidity condition according to ground electric field strength data corresponding to different positive/negative high voltages applied to the target conductor under the current temperature and humidity condition.

Preferably, the second corona onset voltage determining unit 504 is configured to determine, according to corona current data corresponding to different positive/negative high voltages applied to the target conductor under the current temperature and humidity condition, a second positive/negative corona onset voltage of the target conductor under the current temperature and humidity condition.

Preferably, the corona onset electric field strength determining unit 505 is configured to determine a positive/negative corona onset electric field strength of the target conductor under the current temperature and humidity condition according to the first positive/negative corona onset voltage and the second positive/negative corona onset voltage.

Preferably, wherein the system further comprises:

and the incidence relation determining unit is used for adjusting the temperature and the humidity according to a preset adjusting strategy, acquiring the positive/negative corona starting electric field strength of the target lead under different temperature and humidity conditions, and determining the incidence relation between the corona starting electric field strength of the target lead and the temperature and humidity according to the positive/negative corona starting electric field strength of the target lead under different temperature and humidity conditions.

Preferably, the analog line where the target conductor is located is a stranded wire or a thin copper wire, and the insulating rod is made of epoxy resin material.

The system 500 for determining the direct-current corona field strength of the wire according to the embodiment of the present invention corresponds to the method 100 for determining the direct-current corona field strength of the wire according to another embodiment of the present invention, and is not described herein again.

The invention has been described with reference to a few embodiments. However, other embodiments of the invention than the one disclosed above are equally possible within the scope of the invention, as would be apparent to a person skilled in the art from the appended patent claims.

Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to "a/an/the [ device, component, etc ]" are to be interpreted openly as referring to at least one instance of said device, component, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated.

As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.

The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

Finally, it should be noted that: the above embodiments are only for illustrating the technical solutions of the present invention and not for limiting the same, and although the present invention is described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: modifications and equivalents may be made to the embodiments of the invention without departing from the spirit and scope of the invention, which is to be covered by the claims.