阅读说明：本技术 一种确定交叉跨域直流线路的电荷密度初始值的方法 (Method for determining initial value of charge density of cross-domain direct current line ) 是由 马晓倩 谢莉 陆家榆 于 2020-08-24 设计创作，主要内容包括：本申请公开了一种确定交叉跨域直流线路的电荷密度初始值的方法。其中,该方法,包括：根据交叉跨越直流线路合成电场的计算模型以及预先采集的电网参数,确定导线表面电荷密度的基准值以及导线表面各节点的电晕强度系数；根据所述电晕强度系数以及所述导线表面电荷密度的基准值,确定导线表面电荷密度初值；以及根据所述导线表面电荷密度初值,确定每条导线单独存在时在场域各节点处产生的电荷密度初始值,并将所述每条导线单独存在时在场域各节点处产生的电荷密度初始值进行叠加,确定场域各节点的电荷密度初始值。(The application discloses a method for determining an initial value of charge density of a crossed cross-domain direct current line. The method comprises the following steps: determining a reference value of the surface charge density of the wire and a corona intensity coefficient of each node on the surface of the wire according to a calculation model of a cross-over direct-current line synthetic electric field and pre-collected power grid parameters; determining an initial value of the surface charge density of the wire according to the corona intensity coefficient and the reference value of the surface charge density of the wire; and determining initial charge density values generated at nodes of a field area when each conducting wire exists independently according to the initial charge density values on the surfaces of the conducting wires, and superposing the initial charge density values generated at the nodes of the field area when each conducting wire exists independently to determine the initial charge density values of the nodes of the field area.)

1. A method of determining an initial value of charge density for a cross-domain dc line, comprising:

determining a reference value of the surface charge density of the wire and a corona intensity coefficient of each node on the surface of the wire according to a calculation model of a cross-over direct-current line synthetic electric field and pre-collected power grid parameters;

determining an initial value of the surface charge density of the wire according to the corona intensity coefficient and the reference value of the surface charge density of the wire; and

and determining initial charge density values generated at the nodes of the field area when each wire exists independently according to the initial charge density values on the surfaces of the wires, and superposing the initial charge density values generated at the nodes of the field area when each wire exists independently to determine the initial charge density values of the nodes of the field area.

2. The method of claim 1, wherein determining the reference value of the surface charge density of the wire and the corona intensity coefficient of each node on the surface of the wire according to the calculation model of the cross-over direct current line composite electric field and the pre-collected grid parameters comprises:

determining the corona onset field intensity and the corona onset voltage of the pole wire crossing the direct current line according to the calculation model and the pre-collected power grid parameters; and

and determining a reference value of the surface charge density of the wire according to the corona starting field intensity and the corona starting voltage.

3. The method of claim 2, wherein the determining the reference value of the surface charge density of the wire and the corona intensity coefficient of each node on the surface of the wire according to the calculation model of the cross-over direct current line composite electric field and the pre-collected grid parameters further comprises:

determining nominal electric field intensities of different positions on the surface of the lead according to the calculation model and pre-collected power grid parameters; and

and determining the ratio of the nominal electric field intensity and the corona starting field intensity, and determining the ratio as the corona intensity coefficient of each node on the surface of the wire.

4. The method of claim 1, further comprising:

and establishing a calculation model of the cross-crossing direct-current line synthetic electric field.

5. A storage medium comprising a stored program, wherein the method of any one of claims 1 to 4 is performed by a processor when the program is run.

6. An apparatus for determining an initial value of charge density for a cross-domain dc line, comprising:

the first determination module is used for determining a reference value of the surface charge density of the wire and a corona intensity coefficient of each node on the surface of the wire according to a calculation model of a crossed crossing direct-current line synthetic electric field and pre-collected power grid parameters;

the second determination module is used for determining an initial value of the surface charge density of the wire according to the corona intensity coefficient and the reference value of the surface charge density of the wire; and

and the third determining module is used for determining initial charge density values generated at nodes of the field area when each conducting wire exists independently according to the initial charge density values on the surfaces of the conducting wires, and superposing the initial charge density values generated at the nodes of the field area when each conducting wire exists independently to determine the initial charge density values of the nodes of the field area.

7. The apparatus of claim 6, wherein the first determining module comprises:

determining a corona onset submodule, and determining a corona onset field intensity and a corona onset voltage of a pole wire crossing a direct-current line according to the calculation model and pre-collected power grid parameters; and

and determining a reference submodule, and determining a reference value of the surface charge density of the wire according to the corona starting field intensity and the corona starting voltage.

8. The apparatus of claim 7, wherein the first determining module comprises, further comprising:

the field intensity determination submodule determines the nominal electric field intensity of different positions on the surface of the lead according to the calculation model and the pre-collected power grid parameters; and

and the coefficient determination submodule is used for determining the ratio of the nominal electric field intensity and the corona starting field intensity and determining the ratio as the corona intensity coefficient of each node on the surface of the lead.

9. The apparatus of claim 6, further comprising:

and the establishing module is used for establishing a calculation model of the cross-over direct-current line synthetic electric field.

10. An apparatus for determining an initial value of charge density for a cross-domain dc line, comprising:

a processor; and

a memory coupled to the processor for providing instructions to the processor for processing the following processing steps:

determining a reference value of the surface charge density of the wire and a corona intensity coefficient of each node on the surface of the wire according to a calculation model of a cross-over direct-current line synthetic electric field and pre-collected power grid parameters;

determining an initial value of the surface charge density of the wire according to the corona intensity coefficient and the reference value of the surface charge density of the wire; and

and determining initial charge density values generated at the nodes of the field area when each wire exists independently according to the initial charge density values on the surfaces of the wires, and superposing the initial charge density values generated at the nodes of the field area when each wire exists independently to determine the initial charge density values of the nodes of the field area.

Technical Field

The application relates to the field of high-voltage direct-current power transmission, in particular to a method for determining an initial value of charge density of a crossed cross-domain direct-current line.

Background

The electric field around the dc lines is generated by both the line charge and the space charge. Compared with the situation without crossing, when two loops of direct current lines cross, the distribution of the charges of the wires changes, so that the distribution of the surface electric fields of the wires is influenced, the corona degree of the wires and the distribution of space charges change accordingly, and the distribution of the synthesized electric field is influenced finally. In view of this, the resultant electric field around the two loops of dc lines when crossed is different from that when each loop of dc lines exists separately. Therefore, at the beginning of the design of the circuit, the composite electric field when each DC return circuit exists independently is calculated, and the composite electric field in the cross-over area is predicted and controlled to meet the requirement of environmental protection.

Because the current prediction method is immature and the rule of influence of line structure parameters on the synthetic electric field in the cross-over area is unclear, the ground synthetic electric field is generally controlled by greatly increasing the height of the cross-over line in the design of the cross-over direct-current line. However, the method is blindly, the reasonable height of the lead and the house removal range cannot be reasonably determined, the line construction cost can be increased, and the possibility that the ground combined electric field exceeds the standard exists. For this reason, it is necessary to conduct a calculation study of the resultant electric field in the cross-spanning region to determine the appropriate spanning height and to reasonably control the ground resultant electric field. In addition, the research of the crossed crossing composite electric field of the two loops of direct current transmission lines provides a theoretical basis for the prediction of the electromagnetic environment in the environmental impact evaluation. In the crossing area of two loops of direct current transmission lines, an electric field generated by the two loops of lines is a complex three-dimensional field, so that the distribution and the size of a ground synthetic electric field need to be predicted by using a three-dimensional model and a corresponding numerical calculation method.

The three-dimensional up-flow finite element method is an effective discharge which can be used for the theoretical prediction of the three-dimensional synthesis electric field of the direct current transmission line. However, the three-dimensional upstream finite element calculation process is sensitive to the initial charge density value, and the reasonable initial value can only ensure the calculation convergence. The existing charge density initial value calculation method is suitable for the two-dimensional problem or the situation that the surface field intensity of the longitudinal lead along the lead is almost unchanged. However, for two loops of crossing direct current lines, the field intensity variation amplitude of the surface of the lead in the longitudinal direction of the lead in the crossing area is large, so that the corona degrees at different positions in the longitudinal direction of the lead are obviously different, and if the initial charge density value is determined by continuously adopting the conventional initial charge density value calculation formula, iterative calculation cannot be converged. Therefore, it is necessary to research a new charge density initial value calculation formula to ensure the convergence of the calculation process.

Aiming at the technical problem that the iterative calculation cannot converge if the initial charge density value is determined by continuously adopting the conventional initial charge density value calculation formula, an effective solution is not provided at present.

Disclosure of Invention

The embodiment of the disclosure provides a method for determining an initial value of charge density of a cross-domain direct-current line, which is used for solving the technical problems that in the prior art, for two loops of cross-domain direct-current lines, the field intensity variation amplitude of the surface field of a lead in the longitudinal direction of the lead in a cross-domain area is large, so that the corona degrees at different positions in the longitudinal direction of the lead are obviously different, and if the initial value of charge density is determined by continuously adopting the conventional initial value of charge density calculation formula, iterative calculation cannot be converged.

According to an aspect of the embodiments of the present disclosure, there is provided a method for determining an initial value of charge density of a crossed cross-domain dc line, including: determining a reference value of the surface charge density of the wire and a corona intensity coefficient of each node on the surface of the wire according to a calculation model of a cross-over direct-current line synthetic electric field and pre-collected power grid parameters; determining an initial value of the surface charge density of the wire according to the corona intensity coefficient and the reference value of the surface charge density of the wire; and determining initial charge density values generated at nodes of the field area when each wire exists independently according to the initial charge density values on the surfaces of the wires, and superposing the initial charge density values generated at the nodes of the field area when each wire exists independently to determine the initial charge density values of the nodes of the field area.

According to another aspect of the embodiments of the present disclosure, there is also provided a storage medium including a stored program, wherein the method of any one of the above is performed by a processor when the program is executed.

There is also provided, in accordance with another aspect of the disclosed embodiments, an apparatus for determining an initial value of charge density of a crossed cross-domain dc line, including: the first determination module is used for determining a reference value of the surface charge density of the wire and a corona intensity coefficient of each node on the surface of the wire according to a calculation model of a crossed crossing direct-current line synthetic electric field and pre-collected power grid parameters; the second determining module is used for determining an initial value of the surface charge density of the wire according to the corona intensity coefficient and the reference value of the surface charge density of the wire; and the third determining module is used for determining initial charge density values generated at nodes of the field area when each conducting wire exists independently according to the initial charge density values on the surfaces of the conducting wires, and superposing the initial charge density values generated at the nodes of the field area by each conducting wire to determine the initial charge density values of the nodes of the field area.

There is also provided, in accordance with another aspect of the disclosed embodiments, an apparatus for determining an initial value of charge density of a crossed cross-domain dc line, including: a processor; and a memory coupled to the processor for providing instructions to the processor for processing the following processing steps: determining a reference value of the surface charge density of the wire and a corona intensity coefficient of each node on the surface of the wire according to a calculation model of a cross-over direct-current line synthetic electric field and pre-collected power grid parameters; determining an initial value of the surface charge density of the wire according to the corona intensity coefficient and the reference value of the surface charge density of the wire; and determining initial charge density values generated at nodes of the field area when each wire exists independently according to the initial charge density values on the surfaces of the wires, and superposing the initial charge density values generated at the nodes of the field area when each wire exists independently to determine the initial charge density values of the nodes of the field area.

In the embodiment of the disclosure, the distribution of the initial charge density values on the surface of the wire is closer to the real distribution rule, so that the initial charge density values in the solving process of the cross-over direct-current line synthetic electric field are determined by adopting the embodiment, and the program can be stably converged. The method of the embodiment has a wide application range, can be applied to power transmission lines such as single-circuit direct current line pole lead horizontal arrangement, single-circuit direct current line pole lead vertical arrangement, three-circuit direct current lines on the same tower, double-circuit direct current lines on the same corridor and the like, and can ensure the convergence of a three-dimensional synthetic electric field calculation program. Further, the technical problem that the iterative calculation cannot be converged if the initial charge density value is determined by continuously adopting the conventional initial charge density value calculation formula due to the fact that the corona degrees at different positions in the longitudinal direction of the wire are obviously different because the field intensity variation amplitude of the surface of the wire in the longitudinal direction of the wire in the crossed area is large for the two-circuit crossed DC line in the prior art is solved.

Drawings

The accompanying drawings, which are included to provide a further understanding of the disclosure and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the disclosure and together with the description serve to explain the disclosure and not to limit the disclosure. In the drawings:

fig. 1 is a hardware block diagram of a computing device for implementing the method according to embodiment 1 of the present disclosure;

fig. 2 is a schematic flow chart of a method for determining an initial value of charge density of a crossed cross-domain dc line according to a first aspect of embodiment 1 of the present disclosure;

fig. 3 is a schematic flowchart of a method for determining an initial value of charge density of a crossed cross-domain dc line according to a first aspect of embodiment 1 of the present disclosure;

fig. 4 is a schematic diagram of an apparatus for determining an initial value of charge density of a crossed cross-domain dc line according to embodiment 2 of the present disclosure; and

fig. 5 is a schematic diagram of an apparatus for determining an initial value of charge density of a crossed cross-domain dc line according to embodiment 3 of the present disclosure.

Detailed Description

In order to make those skilled in the art better understand the technical solutions of the present disclosure, the technical solutions in the embodiments of the present disclosure will be clearly and completely described below with reference to the drawings in the embodiments of the present disclosure. It is to be understood that the described embodiments are merely exemplary of some, and not all, of the present disclosure. All other embodiments, which can be derived by a person skilled in the art from the embodiments disclosed herein without making any creative effort, shall fall within the protection scope of the present disclosure.

It should be noted that the terms "first," "second," and the like in the description and claims of the present disclosure and in the above-described drawings are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the disclosure described herein are capable of operation in sequences other than those illustrated or otherwise described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.

Example 1

According to the present embodiment, there is also provided an embodiment of a method of determining an initial value of charge density of a cross-domain dc line, it should be noted that the steps illustrated in the flowchart of the drawings may be performed in a computer system such as a set of computer executable instructions, and that although a logical order is illustrated in the flowchart, in some cases the steps illustrated or described may be performed in an order different than here.

The method embodiments provided by the present embodiment may be executed in a server or similar computing device. Fig. 1 shows a block diagram of a hardware configuration of a computing device for implementing a method of determining an initial value of charge density of a crossed cross-domain dc line. As shown in fig. 1, the computing device may include one or more processors (which may include, but are not limited to, a processing device such as a microprocessor MCU or a programmable logic device FPGA), a memory for storing data, and a transmission device for communication functions. Besides, the method can also comprise the following steps: a display, an input/output interface (I/O interface), a Universal Serial Bus (USB) port (which may be included as one of the ports of the I/O interface), a network interface, a power source, and/or a camera. It will be understood by those skilled in the art that the structure shown in fig. 1 is only an illustration and is not intended to limit the structure of the electronic device. For example, the computing device may also include more or fewer components than shown in FIG. 1, or have a different configuration than shown in FIG. 1.

It should be noted that the one or more processors and/or other data processing circuitry described above may be referred to generally herein as "data processing circuitry". The data processing circuitry may be embodied in whole or in part in software, hardware, firmware, or any combination thereof. Further, the data processing circuitry may be a single, stand-alone processing module, or incorporated in whole or in part into any of the other elements in the computing device. As referred to in the disclosed embodiments, the data processing circuit acts as a processor control (e.g., selection of a variable resistance termination path connected to the interface).

The memory may be used to store software programs and modules of application software, such as program instructions/data storage devices corresponding to the method for determining the initial value of charge density of the cross-domain dc line in the embodiment of the present disclosure, and the processor executes various functional applications and data processing by running the software programs and modules stored in the memory, that is, implementing the method for determining the initial value of charge density of the cross-domain dc line of the application software. The memory may include high speed random access memory, and may also include non-volatile memory, such as one or more magnetic storage devices, flash memory, or other non-volatile solid-state memory. In some instances, the memory may further include memory located remotely from the processor, which may be connected to the computing device over a network. Examples of such networks include, but are not limited to, the internet, intranets, local area networks, mobile communication networks, and combinations thereof.

The transmission device is used for receiving or transmitting data via a network. Specific examples of such networks may include wireless networks provided by communication providers of the computing devices. In one example, the transmission device includes a Network adapter (NIC) that can be connected to other Network devices through a base station to communicate with the internet. In one example, the transmission device may be a Radio Frequency (RF) module, which is used for communicating with the internet in a wireless manner.

The display may be, for example, a touch screen type Liquid Crystal Display (LCD) that may enable a user to interact with a user interface of the computing device.

It should be noted here that in some alternative embodiments, the computing device shown in fig. 1 described above may include hardware elements (including circuitry), software elements (including computer code stored on a computer-readable medium), or a combination of both hardware and software elements. It should be noted that FIG. 1 is only one example of a particular specific example and is intended to illustrate the types of components that may be present in a computing device as described above.

According to a first aspect of the present embodiment, there is provided a method of determining an initial value of charge density of a crossed cross-domain dc line. Fig. 2 shows a flow diagram of the method, which, with reference to fig. 2, comprises:

s202: determining a reference value of the surface charge density of the wire and a corona intensity coefficient of each node on the surface of the wire according to a calculation model of a cross-over direct-current line synthetic electric field and pre-collected power grid parameters;

s204: determining an initial value of the surface charge density of the wire according to the corona intensity coefficient and the reference value of the surface charge density of the wire; and

s206: according to the initial value of the surface charge density of the conducting wires, the initial value of the charge density generated at each node of the field area when each conducting wire exists independently is determined, and the initial values of the charge density generated at each node of the field area when each conducting wire exists independently are superposed to determine the initial value of the charge density of each node of the field area.

In this embodiment, a computational model of the cross-over dc link composite electric field is first built. The basic equation of the three-dimensional synthetic electric field under the condition of the cross crossing of the two loops of direct current transmission lines is as follows:

wherein the content of the first and second substances,is an electric potential; rho₊、ρ_-Positive and negative space charge densities, respectively; epsilon₀Is the dielectric constant of air; e_sA composite electric field; k is a radical of₊、k_-Positive and negative ion mobility, respectively; omega is the wind speed; r is the positive and negative ion recombination coefficient; e is the elementary charge capacity.

For ease of analysis, the following assumptions were used in the calculation process: 1) neglecting the corona layer thickness; 2) the surface electric field intensity of the line after the line is stunned is kept unchanged at the stunning value (Kaptzov assumption); 3) ion mobility is considered to be a constant independent of electric field strength and ion lifetime, i.e. ion mobility is equal everywhere; 4) the diffusion of space charge is not considered.

The finite element method requires that the infinite calculation domain of the direct current transmission line synthetic electric field is approximated to a finite domain. The specific method is that a hypothetical boundary (artificial boundary) is manually drawn at a position far away from the wire, and a closed area surrounded by the surface of the wire, the ground and the artificial boundary is a calculation field area. Accordingly, the boundary conditions of the calculation region are: surface of the lead:ground surface:artificial boundary:wherein U is the pole conductor operating voltage, E_onField strength of corona for polar wire, U_3DIs the result of a three-dimensional calculation of the nominal field potential. In order to complete finite element calculation, a tetrahedral unit is adopted to divide a calculation field into discrete systems.

Referring to fig. 2 and 3, a reference value of the surface charge density of the wire and a corona intensity coefficient of each node on the surface of the wire are determined according to a calculation model of a cross-over direct-current line composite electric field and pre-collected power grid parameters. For example, the pole wire corona onset field strength and corona onset voltage of the crossed crossing direct current line are determined and calculated according to the pole wire radius, the total number of the pole wires and the like acquired in advance. The corona onset field intensity E of each polar wire is respectively calculated by the following formula_on(i)：

Wherein i is the pole wire number; n is a radical of_cThe total number of pole leads; m is the surface roughness coefficient of the wire; delta is the relative density of air; r is the polar wire radius; e₀And k are respectively fixed coefficients, when the voltage of the polar lead is positive, E₀33.7, k 0.24, and the on-pole line voltageIs negative, E₀＝31，k＝0.308。

Solving the corona onset voltage U of each polar wire according to the following relation₀(i)：

Wherein E is_e(i) The average value of the nominal electric field at the surface of the wire, and U (i) the operating voltage of the polar wire.

And calculating the nominal electric field intensity of different positions on the surface of the crossed and crossed direct-current line pole wire by using a three-dimensional optimization analog line charge method. And calculating the reference value of the surface charge density of the pole wire by using parameters such as the field intensity, the corona voltage, the height and the like of the corona field crossing the pole wire of the direct current line. The calculation formula of the cross-over direct current line pole wire surface charge density reference value is as follows:

wherein U (i) is the operating voltage of the pole wire i; e_g(i) The average value of the ground nominal electric field right below the axis of the polar lead is obtained; h (i) is the height of pole wire i to ground.

The corona strength coefficients at different positions (i.e. the corona strength coefficients of the nodes on the surface of the wire) are calculated from the ratio of the nominal electric field strength and the corona onset field strength at the points on the surface of the wire crossing the dc line poles.

The solving formula of the corona intensity coefficients at different positions on the surface of the polar wire is as follows:

C_corona(P)⁽ⁱ⁾＝E_sur(P)⁽ⁱ⁾/E_on(i)

wherein, C_corona(P)⁽ⁱ⁾Representing the corona intensity coefficient at the i-surface node P of the pole wire, E_sur(P)⁽ⁱ⁾Is the nominal electric field at node P at the surface of the pole wire i.

Further, an initial value of the surface charge density of the wire is determined according to the corona intensity coefficient and the reference value of the surface charge density of the wire. And multiplying the corona intensity coefficients at different positions on the surface of the pole wire crossing the direct current line by the reference value of the surface charge density of the pole wire to calculate the initial value of the surface charge density of the pole wire. The solving formula of the initial value of the charge density at any node P on the surface of the polar lead is as follows:

p_sur,0(p)⁽ⁱ⁾＝p_sur,b(i).C_corona(p)⁽ⁱ⁾

where ρ is_sur,0(P)⁽ⁱ⁾Represents the initial value of the charge density at node P at the surface of pole wire i.

Further, according to the initial value of the surface charge density of the pole conducting wires, the initial value of the charge density at each node of the space (namely the field) when each pole conducting wire exists independently is calculated. When each polar conducting wire exists independently, the initial value of the charge density of any point M in space can be approximated by adopting a space charge density analytic solution of a coaxial cylinder:

where ρ is₀(M)⁽ⁱ⁾Represents the initial value of the space charge density generated at node M when pole wire i alone is present; r is_MIs the distance of point M from the wire axis. In a plane passing through the point M and perpendicular to the conductive lineN is selected from boundary circle of outer surface of wire_sEach node is solved to obtain an initial value of the surface charge density,to this n_sThe charge density of each node is averaged. And superposing the charge density at each point in space when each polar lead exists independently to obtain an initial value of the space charge density.

The initial charge density value solving formula of any point M in space is as follows:

where ρ is₀(M) represents an initial value of the charge density at any point M in space (i.e., field). The method of the embodiment can be applied to the calculation of the combined electric field of the power transmission lines such as the single-circuit direct current power transmission line pole lead horizontal arrangement, the single-circuit direct current power transmission line pole lead vertical arrangement, the same-tower three-circuit direct current power transmission line, the same-corridor double-circuit direct current power transmission line, the cross-over direct current power transmission line and the like.

Therefore, the distribution of the initial values of the surface charge density of the wire obtained by the embodiment is closer to the real distribution rule, and therefore, the program can be stably converged by determining the initial values of the charge density in the solving process of the cross-over direct-current line synthetic electric field. The method of the embodiment has a wide application range, can be applied to power transmission lines such as single-circuit direct current line pole lead horizontal arrangement, single-circuit direct current line pole lead vertical arrangement, three-circuit direct current lines on the same tower, double-circuit direct current lines on the same corridor and the like, and can ensure the convergence of a three-dimensional synthetic electric field calculation program.

Optionally, determining a reference value of the surface charge density of the wire and a corona intensity coefficient of each node on the surface of the wire according to a calculation model of a cross-over direct-current line synthetic electric field and pre-collected power grid parameters, including: determining the corona onset field intensity and the corona onset voltage of a pole wire crossing a direct current line according to the calculation model and pre-collected power grid parameters; and determining a reference value of the surface charge density of the wire according to the corona-starting field intensity and the corona-starting voltage.

Specifically, for example, the pole wire corona onset field strength and corona onset voltage across the dc line are determined and calculated based on pre-collected pole wire radii, pole wire total, and the like. The corona onset field intensity E of each polar wire is respectively calculated by the following formula_on(i)：

Wherein i is the pole wire number; n is a radical of_cThe total number of pole leads; m is the surface roughness coefficient of the wire; delta is the relative density of air; r is the polar wire radius; e₀And k are respectively fixed coefficients, when the voltage of the polar lead is positive, E₀33.7, k is 0.24, and when the pole wire voltage is negative, E₀＝31，k＝0.308。

Solving the corona onset voltage U of each polar wire according to the following relation₀(i)：

Wherein E is_e(i) The average value of the nominal electric field at the surface of the wire, and U (i) the operating voltage of the polar wire.

And calculating the nominal electric field intensity of different positions on the surface of the crossed and crossed direct-current line pole wire by using a three-dimensional optimization analog line charge method. And calculating the reference value of the surface charge density of the pole wire by using parameters such as the field intensity, the corona voltage, the height and the like of the corona field crossing the pole wire of the direct current line. The calculation formula of the cross-over direct current line pole wire surface charge density reference value is as follows:

wherein U (i) is the operating voltage of the pole wire i; e_g(i) The average value of the ground nominal electric field right below the axis of the polar lead is obtained; h (i) is the height of pole wire i to ground. Thereby defining a leadA reference value of surface charge density.

Optionally, determining a reference value of the surface charge density of the wire and a corona intensity coefficient of each node on the surface of the wire according to a calculation model of a cross-over direct-current line synthetic electric field and pre-collected power grid parameters, and further comprising: determining nominal electric field intensities of different positions on the surface of the lead according to the calculation model and pre-collected power grid parameters; and determining the ratio of the nominal electric field intensity and the starting corona field intensity, and determining the ratio as the corona intensity coefficient of each node on the surface of the wire.

Specifically, according to a calculation model and pre-collected power grid parameters, determining nominal electric field strengths of different positions on the surface of the lead; and determining the ratio of the nominal electric field intensity and the starting corona field intensity, and determining the ratio as the corona intensity coefficient of each node on the surface of the wire. Calculating the corona intensity coefficients at different positions according to the ratio of the nominal electric field intensity and the corona starting field intensity at each point of the surface of the cross-over direct current line polar wire. The solving formula of the corona intensity coefficients at different positions on the surface of the polar wire is as follows:

C_corona(P)⁽ⁱ⁾＝E_sur(P)⁽ⁱ⁾/E_on(i)

wherein, C_corona(P)⁽ⁱ⁾Representing the corona intensity coefficient at the i-surface node P of the pole wire, E_sur(P)⁽ⁱ⁾Is the nominal electric field at node P at the surface of the pole wire i. Thereby determining the corona intensity coefficient of each node on the surface of the wire.

Optionally, the method further comprises: and establishing a calculation model of the cross-crossing direct-current line synthetic electric field.

Further, referring to fig. 1, according to a second aspect of the present embodiment, there is provided a storage medium. The storage medium comprises a stored program, wherein the method of any of the above is performed by a processor when the program is run.

Therefore, the distribution of the initial values of the surface charge density of the wires obtained according to the embodiment is closer to the real distribution rule, and therefore, the initial values of the charge density in the solving process of the cross-over direct-current line synthetic electric field are determined by adopting the embodiment, and the program can be stably converged. The method of the embodiment has a wide application range, can be applied to power transmission lines such as single-circuit direct current line pole lead horizontal arrangement, single-circuit direct current line pole lead vertical arrangement, three-circuit direct current lines on the same tower, double-circuit direct current lines on the same corridor and the like, and can ensure the convergence of a three-dimensional synthetic electric field calculation program. Further, the technical problem that the iterative calculation cannot be converged if the initial charge density value is determined by continuously adopting the conventional initial charge density value calculation formula due to the fact that the corona degrees at different positions in the longitudinal direction of the wire are obviously different because the field intensity variation amplitude of the surface of the wire in the longitudinal direction of the wire in the crossed area is large for the two-circuit crossed DC line in the prior art is solved.

It should be noted that, for simplicity of description, the above-mentioned method embodiments are described as a series of acts or combination of acts, but those skilled in the art will recognize that the present invention is not limited by the order of acts, as some steps may occur in other orders or concurrently in accordance with the invention. Further, those skilled in the art should also appreciate that the embodiments described in the specification are preferred embodiments and that the acts and modules referred to are not necessarily required by the invention.

Through the above description of the embodiments, those skilled in the art can clearly understand that the method according to the above embodiments can be implemented by software plus a necessary general hardware platform, and certainly can also be implemented by hardware, but the former is a better implementation mode in many cases. Based on such understanding, the technical solutions of the present invention may be embodied in the form of a software product, which is stored in a storage medium (e.g., ROM/RAM, magnetic disk, optical disk) and includes instructions for enabling a terminal device (e.g., a mobile phone, a computer, a server, or a network device) to execute the method according to the embodiments of the present invention.

Example 2

Fig. 4 shows an apparatus 400 for determining an initial value of the charge density of a crossed cross-domain dc line according to the present embodiment, where the apparatus 400 corresponds to the method according to the first aspect of embodiment 1. Referring to fig. 4, the apparatus 400 includes: the first determining module 410 is configured to determine a reference value of the surface charge density of the wire and a corona intensity coefficient of each node on the surface of the wire according to a calculation model of a cross-over direct-current line synthetic electric field and pre-collected power grid parameters; the second determining module 420 is configured to determine an initial value of the surface charge density of the wire according to the corona intensity coefficient and the reference value of the surface charge density of the wire; and a third determining module 430, configured to determine initial charge density values generated at nodes of the field area when each conducting wire exists alone according to the initial charge density values on the surface of the conducting wires, and determine initial charge density values of the nodes of the field area by superimposing the initial charge density values generated at the nodes of the field area when each conducting wire exists alone.

Optionally, the first determining module 410 includes: determining a corona onset submodule, and determining a corona onset field intensity and a corona onset voltage of a pole wire crossing a direct-current line according to a calculation model and pre-collected power grid parameters; and the reference submodule determines a reference value of the surface charge density of the wire according to the corona starting field intensity and the corona starting voltage.

Optionally, the first determining module includes 410, further including: the field intensity determination submodule determines the nominal electric field intensity of different positions on the surface of the lead according to the calculation model and the pre-collected power grid parameters; and the coefficient determination submodule is used for determining the ratio of the nominal electric field intensity and the corona onset field intensity and determining the ratio as the corona intensity coefficient of each node on the surface of the lead.

Optionally, the apparatus 400 further comprises: and the establishing module is used for establishing a calculation model of the cross-over direct-current line synthetic electric field.

Therefore, the distribution of the initial values of the surface charge density of the wires obtained according to the embodiment is closer to the real distribution rule, and therefore, the initial values of the charge density in the solving process of the cross-over direct-current line synthetic electric field are determined by adopting the embodiment, and the program can be stably converged. The method of the embodiment has a wide application range, can be applied to power transmission lines such as single-circuit direct current line pole lead horizontal arrangement, single-circuit direct current line pole lead vertical arrangement, three-circuit direct current lines on the same tower, double-circuit direct current lines on the same corridor and the like, and can ensure the convergence of a three-dimensional synthetic electric field calculation program. Further, the technical problem that the iterative calculation cannot be converged if the initial charge density value is determined by continuously adopting the conventional initial charge density value calculation formula due to the fact that the corona degrees at different positions in the longitudinal direction of the wire are obviously different because the field intensity variation amplitude of the surface of the wire in the longitudinal direction of the wire in the crossed area is large for the two-circuit crossed DC line in the prior art is solved.

Example 3

Fig. 5 shows an apparatus 500 for determining an initial value of the charge density of a crossed cross-domain dc line according to the present embodiment, the apparatus 500 corresponding to the method according to the first aspect of embodiment 1. Referring to fig. 5, the apparatus 500 includes: a processor 510; and a memory 520 coupled to processor 510 for providing processor 510 with instructions to process the following process steps: determining a reference value of the surface charge density of the wire and a corona intensity coefficient of each node on the surface of the wire according to a calculation model of a cross-over direct-current line synthetic electric field and pre-collected power grid parameters; determining an initial value of the surface charge density of the wire according to the corona intensity coefficient and the reference value of the surface charge density of the wire; and determining initial charge density values generated at nodes of the field area when each wire exists independently according to the initial charge density values on the surfaces of the wires, and superposing the initial charge density values generated at the nodes of the field area when each wire exists independently to determine the initial charge density values of the nodes of the field area.

Optionally, determining a reference value of the surface charge density of the wire and a corona intensity coefficient of each node on the surface of the wire according to a calculation model of a cross-over direct-current line synthetic electric field and pre-collected power grid parameters, including: determining the corona onset field intensity and the corona onset voltage of a pole wire crossing a direct current line according to the calculation model and pre-collected power grid parameters; and determining a reference value of the surface charge density of the wire according to the corona-starting field intensity and the corona-starting voltage.

Optionally, determining a reference value of the surface charge density of the wire and a corona intensity coefficient of each node on the surface of the wire according to a calculation model of a cross-over direct-current line synthetic electric field and pre-collected power grid parameters, and further comprising: determining nominal electric field intensities of different positions on the surface of the lead according to the calculation model and pre-collected power grid parameters; and determining the ratio of the nominal electric field intensity and the starting corona field intensity, and determining the ratio as the corona intensity coefficient of each node on the surface of the wire.

Optionally, the instructions for providing processor 510 with processing steps further comprise: and establishing a calculation model of the cross-crossing direct-current line synthetic electric field.

Therefore, the distribution of the initial values of the surface charge density of the wires obtained according to the embodiment is closer to the real distribution rule, and therefore, the initial values of the charge density in the solving process of the cross-over direct-current line synthetic electric field are determined by adopting the embodiment, and the program can be stably converged. The method of the embodiment has a wide application range, can be applied to power transmission lines such as single-circuit direct current line pole lead horizontal arrangement, single-circuit direct current line pole lead vertical arrangement, three-circuit direct current lines on the same tower, double-circuit direct current lines on the same corridor and the like, and can ensure the convergence of a three-dimensional synthetic electric field calculation program. Further, the technical problem that the iterative calculation cannot be converged if the initial charge density value is determined by continuously adopting the conventional initial charge density value calculation formula due to the fact that the corona degrees at different positions in the longitudinal direction of the wire are obviously different because the field intensity variation amplitude of the surface of the wire in the longitudinal direction of the wire in the crossed area is large for the two-circuit crossed DC line in the prior art is solved.

The above-mentioned serial numbers of the embodiments of the present invention are merely for description and do not represent the merits of the embodiments.

In the above embodiments of the present invention, the descriptions of the respective embodiments have respective emphasis, and for parts that are not described in detail in a certain embodiment, reference may be made to related descriptions of other embodiments.

In the embodiments provided in the present application, it should be understood that the disclosed technology can be implemented in other ways. The above-described embodiments of the apparatus are merely illustrative, and for example, the division of the units is only one type of division of logical functions, and there may be other divisions when actually implemented, for example, a plurality of units or components may be combined or may be integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, units or modules, and may be in an electrical or other form.

The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.

In addition, functional units in the embodiments of the present invention may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit. The integrated unit can be realized in a form of hardware, and can also be realized in a form of a software functional unit.

The integrated unit, if implemented in the form of a software functional unit and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present invention may be embodied in the form of a software product, which is stored in a storage medium and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the method according to the embodiments of the present invention. And the aforementioned storage medium includes: a U-disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a removable hard disk, a magnetic or optical disk, and other various media capable of storing program codes.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.