Contact resistance modeling method and device, terminal equipment and storage medium

Abstract

The invention discloses a contact resistance modeling method and device, terminal equipment and a storage medium. The method comprises the steps that the tree diameter, the air breakdown field strength, the external voltage, the breakdown area radial length and the unit contact resistance are acquired; calculating the initial breakdown area of the contact area according to the tree diameter, the air breakdown field strength, the external voltage and the radial length of the breakdown area; and according to the initial breakdown area and the unit contact resistance, constructing a resistance function formula of the contact resistance changing along with time, and taking the resistance function formula as a contact resistance model. According to the method, the specific tree diameter, the air breakdown field strength, the external voltage, the breakdown area radial length and the unit contact resistance parameters are obtained, the method is used for finely depicting a model of the wire contact tree fault contact resistance, and the technical blank of fine modeling of the contact resistance is filled.

Description

Technical Field

[0001] The present invention relates to the field of power system fault detection, and in particular to a contact resistance modeling method, device, terminal equipment and storage medium. Background Art

[0002] A wire-on-tree fault is a fault caused by the overlap of an overhead line with tree bark due to tree growth or wire sagging. It is one of the main types of faults in overhead lines in distribution networks. Since the bark at the contact point has poor conductivity, the moisture and temperature parameters in the conductive channel such as the trunk change due to the thermal effect of the current. The wire-on-tree fault has fault characteristics such as high resistance and is accompanied by a long development process. Existing fault detection and protection methods are difficult to quickly handle in the embryonic stage of a wire-on-tree fault, resulting in a permanent ground fault and even further causing a tree fire, which seriously affects the safe and reliable power supply of the distribution network.

[0003] At present, most existing studies attribute the wire-contact-tree fault to arc-light high-resistance faults, and model the wire-contact-tree process by introducing arc models such as traditional arc models based on energy balance equations, logarithmic models, piecewise linear models, and cybernetics models. This type of method does not specifically analyze and model the mechanism of wire-contact-tree faults, and can only reflect the common characteristics of arc-light high-resistance grounding faults, but cannot characterize the change law of contact resistance of wire-contact-tree faults. Some studies have also proposed cybernetics models based on measured data, but the system parameters and topological structures in the actual distribution network are variable, and the parameters such as the types of trees that the overhead lines contact also vary greatly. The cybernetics model has poor interpretability and is not universal. In summary, due to the difficulties in analyzing the mechanism of the formation process of the plasma area near the contact point between the conductor and the bark, there is a gap in the research on fine modeling of contact resistance. Summary of the invention

[0004] The present invention provides a contact resistance modeling method, an apparatus, a terminal device and a storage medium to solve the technical blank problem of contact resistance fine modeling.

[0005] In order to solve the above technical problems, an embodiment of the present invention provides a contact resistance modeling method, comprising:

[0006] Obtain tree diameter, air breakdown field strength, external voltage, radial length of breakdown region and unit contact resistance;

[0007] calculating the initial breakdown area of ​​the contact region according to the tree diameter, the air breakdown field strength, the external voltage and the radial length of the breakdown region;

[0008] According to the initial breakdown area and the unit contact resistance, a resistance function formula of the contact resistance changing with time is constructed as a contact resistance model.

[0009] As a preferred solution, the initial breakdown area of ​​the contact region is calculated according to the tree diameter, the air breakdown field strength, the external voltage and the length of the breakdown region in the radial direction of the conductor, including:

[0010] The initial breakdown region deviation distance is calculated according to the tree diameter, the air breakdown field strength and the external voltage; wherein the breakdown region deviation distance refers to the distance from the edge of the breakdown region in the axial direction of the conductor to the contact point;

[0011] The initial breakdown area is calculated according to the deviation distance of the initial breakdown region and the radial length of the breakdown region.

[0012] As a preferred solution, the calculation formula for the initial breakdown region offset distance is:

[0013]

[0014] Where x0 represents the offset distance of the initial breakdown area; R T represents the tree diameter; U represents the external voltage; E0 represents the air breakdown field strength.

[0015] As a preferred solution, the calculation formula for the initial breakdown region area is:

[0016] S0=x0·l;

[0017] Where S0 represents the area of ​​the initial breakdown region; x0 represents the deviation distance of the initial breakdown region; l represents the radial length of the breakdown region.

[0018] As a preferred solution, the resistance function formula of the contact resistance changing with time is constructed according to the initial breakdown area and the unit contact resistance, including:

[0019] According to the initial breakdown area and the unit contact resistance, a conductance function formula of the contact conductance changing with time is constructed;

[0020] The resistance function formula is constructed according to the conductance function formula.

[0021] As a preferred solution, the conductance function formula is:

[0022]

[0023] Where g represents conductivity; σ s represents unit contact resistance; S0 represents initial breakdown area; t represents parameter time; K1 represents expansion area coefficient; K2 represents breakdown rate coefficient.

[0024] As a preferred solution, the resistance function formula is:

[0025]

[0026] In the formula, R represents resistance; g represents conductance; and t represents parameter time.

[0027] Based on the above embodiment, another embodiment of the present invention provides a contact resistance modeling device, including: a data acquisition module and a modeling module;

[0028] The data acquisition module is used to obtain the tree diameter, air breakdown field strength, external voltage, radial length of the breakdown area and unit contact resistance;

[0029] The modeling module is used to calculate the initial breakdown area of ​​the contact region according to the tree diameter, air breakdown field strength, external voltage and radial length of the breakdown region; and to construct a resistance function formula of the contact resistance changing with time as a contact resistance model according to the initial breakdown area and unit contact resistance.

[0030] Based on the above embodiments, another embodiment of the present invention provides a terminal device, which includes a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, and when the processor executes the computer program, the contact resistance modeling method described in the above invention embodiment is implemented.

[0031] Based on the above embodiment, another embodiment of the present invention provides a storage medium, which includes a stored computer program, wherein when the computer program is running, the device where the storage medium is located is controlled to execute the contact resistance modeling method described in the above invention embodiment.

[0032] Compared with the prior art, the embodiments of the present invention have the following beneficial effects:

[0033] The tree diameter, air breakdown field strength, external voltage, radial length of the breakdown area and unit contact resistance are obtained; the initial breakdown area of ​​the contact area is calculated according to the tree diameter, air breakdown field strength, external voltage and radial length of the breakdown area; according to the initial breakdown area and unit contact resistance, a resistance function formula of the contact resistance changing with time is constructed as a contact resistance model. The present invention obtains specific tree diameter, air breakdown field strength, external voltage, radial length of the breakdown area and unit contact resistance parameters for finely characterizing the model of contact resistance of wire touching tree fault, filling the technical gap of fine modeling of contact resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a flow chart of a contact resistance modeling method provided by one embodiment of the present invention;

[0035] Figure 2It is a structural schematic diagram of a contact resistance modeling device provided by one embodiment of the present invention;

[0036] Figure 3 This is a schematic diagram of the air gap near the contact point between the wire and the bark. DETAILED DESCRIPTION

[0037] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0038] Embodiment 1

[0039] Please refer to Figure 1 , is a flow chart of a contact resistance modeling method provided by an embodiment of the present invention, comprising:

[0040] S1. Obtain the tree diameter, air breakdown field strength, external voltage, radial length of the breakdown area, and unit contact resistance.

[0041] In step S1, the tree diameter R is obtained. T , air breakdown field strength E0, external voltage U, radial length l of the breakdown region and unit contact resistance σ s .

[0042] It should be noted that the radial length of the breakdown region l refers to the length of the breakdown region in the radial direction of the conductor; the air breakdown field strength E0 refers to the air breakdown field strength at room temperature; the unit contact resistance σ s It refers to the contact resistance per unit contact area between the conductor and the bark.

[0043] S2. Calculate the initial breakdown area of ​​the contact region according to the tree diameter, air breakdown field strength, external voltage and radial length of the breakdown region.

[0044] In a preferred embodiment, the initial breakdown area of ​​the contact region is calculated according to the tree diameter, the air breakdown field strength, the external voltage and the breakdown region length in the radial direction of the conductor, including:

[0045] The initial breakdown region deviation distance is calculated according to the tree diameter, the air breakdown field strength and the external voltage; wherein the breakdown region deviation distance refers to the distance from the edge of the breakdown region in the axial direction of the conductor to the contact point;

[0046] The initial breakdown area is calculated according to the deviation distance of the initial breakdown region and the radial length of the breakdown region.

[0047] In a preferred embodiment, the calculation formula of the initial breakdown region offset distance is:

[0048]

[0049] Where x0 represents the offset distance of the initial breakdown area; R T represents the tree diameter; U represents the external voltage; E0 represents the air breakdown field strength.

[0050] In a preferred embodiment, the calculation formula of the initial breakdown region area is:

[0051] S0=x0·l;

[0052] Where S0 represents the area of ​​the initial breakdown region; x0 represents the deviation distance of the initial breakdown region; l represents the radial length of the breakdown region.

[0053] It should be noted that the derivation process of the calculation formula for the initial breakdown area offset distance is as follows:

[0054] Assume that the gap distance between the wire and the bark at the distance x from the contact point is d, and the corresponding offset angle is θ, as shown in Figure 3 shown.

[0055] According to the geometric relationship, we get:

[0056]

[0057] The breakdown field strength at the boundary x of the breakdown region at time t satisfies:

[0058]

[0059] At time t1, the boundary of the breakdown region is x1. As heat accumulates in the region, the temperature rises, the degree of gas ionization increases, and the breakdown field strength decreases. At time t2, the boundary of the new breakdown region x2 satisfies:

[0060] E(x1,t1)>E(x2,t2);

[0061]

[0062] Thus we get:

[0063] x2>x1;

[0064] Therefore, as time goes by, the distance between the breakdown region boundary and the contact point gradually increases.

[0065] Since the axial length of the wire is much larger than the radial dimension, the breakdown area develops more obviously along the axial direction, deviating from the direction where the distance between the contact points increases. To simplify the calculation, the radial length of the breakdown area is replaced by the radial length of the breakdown area l, and the area of ​​the breakdown area can be written as:

[0066] S = x·l;

[0067] As the breakdown area increases, the heat generated in the breakdown area increases, the temperature increases, the acceleration of the gas ionization in the adjacent area becomes more obvious, and the rate of increase of the breakdown area increases. However, the increase of the breakdown area will also increase the heat dissipation, so the breakdown area will not continue to increase, but will eventually reach a steady-state value, and the heat generated in the breakdown area is balanced with the heat dissipated to the surrounding area. Assuming that the rate of increase of the breakdown area is a quadratic function of the area of ​​the breakdown area, and the steady-state value of the breakdown area is S1, then:

[0068]

[0069] Solving the above formula, we get:

[0070]

[0071] Where A satisfies:

[0072]

[0073] At the initial moment, the air is not heated, so the field strength in the initial breakdown region is equal to the air breakdown field strength E0:

[0074]

[0075] then,

[0076]

[0077] S3. According to the initial breakdown area and the unit contact resistance, a resistance function formula of the contact resistance changing with time is constructed as a contact resistance model.

[0078] In a preferred embodiment, the resistance function formula of the contact resistance changing with time is constructed according to the initial breakdown area and the unit contact resistance, including:

[0079] According to the initial breakdown area and the unit contact resistance, a conductance function formula of the contact conductance changing with time is constructed;

[0080] The resistance function formula is constructed according to the conductance function formula.

[0081] In a preferred embodiment, the conductance function formula is:

[0082]

[0083] Where g represents conductivity; σ srepresents unit contact resistance; S0 represents initial breakdown area; t represents parameter time; K1 represents expansion area coefficient; K2 represents breakdown rate coefficient.

[0084] It should be noted that the value of K1 is generally 50, and the value of K2 is generally 0.1.

[0085] In a preferred embodiment, the resistance function formula is:

[0086]

[0087] In the formula, R represents resistance; g represents conductance; and t represents parameter time.

[0088] It should be noted that, based on mechanism analysis, the present invention establishes an air breakdown area expansion model that accurately depicts the contact resistance of wire tree contact faults, which provides a theoretical basis for the research on wire tree contact fault warning and fault identification, fills the technical gap in the fine modeling of contact resistance, and has positive significance for reducing the risk of distribution network accidents and reducing line hidden dangers.

[0089] Embodiment 2

[0090] Please refer to Figure 2 , is a schematic structural diagram of a contact resistance modeling device provided by an embodiment of the present invention, comprising: a data acquisition module and a modeling module;

[0091] The data acquisition module is used to obtain the tree diameter, air breakdown field strength, external voltage, radial length of the breakdown area and unit contact resistance;

[0092] The modeling module is used to calculate the initial breakdown area of ​​the contact region according to the tree diameter, air breakdown field strength, external voltage and radial length of the breakdown region; and to construct a resistance function formula of the contact resistance changing with time as a contact resistance model according to the initial breakdown area and unit contact resistance.

[0093] Embodiment 3

[0094] Accordingly, an embodiment of the present invention provides a terminal device, which includes a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, and when the processor executes the computer program, the contact resistance modeling method described in the above-mentioned embodiment of the invention is implemented.

[0095] Embodiment 4

[0096] Accordingly, an embodiment of the present invention provides a storage medium, which includes a stored computer program, wherein when the computer program is running, the device where the storage medium is located is controlled to execute the contact resistance modeling method described in the above-mentioned embodiment of the invention.

[0097] It should be noted that the device embodiments described above are merely schematic, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. In addition, in the accompanying drawings of the device embodiments provided by the present invention, the connection relationship between the modules indicates that there is a communication connection between them, which may be specifically implemented as one or more communication buses or signal lines. A person of ordinary skill in the art may understand and implement it without paying any creative effort.

[0098] Those skilled in the art can clearly understand that for the sake of convenience and brevity, the specific working process of the device described above can refer to the corresponding process in the aforementioned method embodiment, and will not be repeated here.

[0099] The terminal device may be a computing device such as a desktop computer, a notebook, a PDA, a cloud server, etc. The terminal device may include, but is not limited to, a processor and a memory.

[0100] The processor may be a central processing unit (CPU), or other general-purpose processors, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or any conventional processor, etc. The processor is the control center of the device, and various interfaces and lines are used to connect various parts of the entire device.

[0101] The memory can be used to store the computer program, and the processor realizes various functions of the device by running or executing the computer program stored in the memory and calling the data stored in the memory. The memory can mainly include a program storage area and a data storage area, wherein the program storage area can store an operating system, at least one application required for a function, etc.; the data storage area can store data created according to the use of the mobile phone, etc. In addition, the memory can include a high-speed random access memory, and can also include a non-volatile memory, such as a hard disk, a memory, a plug-in hard disk, a smart memory card (Smart Med ia Card, SMC), a secure digital (Secure Digital, SD) card, a flash card (Flash Card), at least one disk storage device, a flash memory device, or other volatile solid-state storage devices.

[0102] The storage medium is a storage medium, and the computer program is stored in the storage medium. When the computer program is executed by the processor, the steps of each method embodiment described above can be implemented. Among them, the computer program includes computer program code, and the computer program code can be in source code form, object code form, executable file or some intermediate form, etc. The computer readable medium may include: any entity or device capable of carrying the computer program code, recording medium, USB flash drive, mobile hard disk, disk, optical disk, computer memory, read-only memory (ROM, Read-On l yMemory), random access memory (RAM, Random Access Memory), electric carrier signal, telecommunication signal and software distribution medium, etc. It should be noted that the content contained in the computer readable medium can be appropriately increased or decreased according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, computer readable media do not include electric carrier signals and telecommunication signals.

[0103] The above is a preferred embodiment of the present invention. It should be pointed out that a person skilled in the art can make several improvements and modifications without departing from the principle of the present invention. These improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A contact resistance modeling method, characterized in that: include: Obtain tree diameter, air breakdown field strength, external voltage, radial length of breakdown region and unit contact resistance; calculating the initial breakdown area of ​​the contact region according to the tree diameter, the air breakdown field strength, the external voltage and the radial length of the breakdown region; According to the initial breakdown area and the unit contact resistance, a resistance function formula of the contact resistance changing with time is constructed as a contact resistance model.

2. The contact resistance modeling method according to claim 1, characterized in that: The method of calculating the initial breakdown area of ​​the contact region according to the tree diameter, the air breakdown field strength, the external voltage and the breakdown region length in the radial direction of the conductor comprises: The initial breakdown region deviation distance is calculated according to the tree diameter, the air breakdown field strength and the external voltage; wherein the breakdown region deviation distance refers to the distance from the edge of the breakdown region in the axial direction of the conductor to the contact point; The initial breakdown area is calculated according to the deviation distance of the initial breakdown region and the radial length of the breakdown region.

3. The contact resistance modeling method according to claim 2, characterized in that: The calculation formula of the initial breakdown region offset distance is: Where x0 represents the offset distance of the initial breakdown area; R T represents the tree diameter; U represents the external voltage; E0 represents the air breakdown field strength.

4. The contact resistance modeling method according to claim 2, characterized in that: The calculation formula of the initial breakdown region area is: S0=x0·l; Where S0 represents the area of ​​the initial breakdown region; x0 represents the deviation distance of the initial breakdown region; l represents the radial length of the breakdown region.

5. The contact resistance modeling method according to claim 1, characterized in that: The step of constructing a resistance function formula of the contact resistance changing with time based on the initial breakdown area and the unit contact resistance includes: According to the initial breakdown area and the unit contact resistance, a conductance function formula of the contact conductance changing with time is constructed; The resistance function formula is constructed according to the conductance function formula.

6. The contact resistance modeling method according to claim 5, characterized in that: The conductance function formula is: Where g represents conductivity; σ s represents unit contact resistance; S0 represents initial breakdown area; t represents parameter time; K1 represents expansion area coefficient; K2 represents breakdown rate coefficient.

7. The contact resistance modeling method according to claim 5, characterized in that: The resistance function formula is: Where R represents resistance; g represents conductance; and t represents parameter time.

8. A contact resistance modeling device, characterized in that: include: Data acquisition module and modeling module; The data acquisition module is used to obtain the tree diameter, air breakdown field strength, external voltage, radial length of the breakdown area and unit contact resistance; The modeling module is used to calculate the initial breakdown area of ​​the contact region according to the tree diameter, air breakdown field strength, external voltage and radial length of the breakdown region; and to construct a resistance function formula of the contact resistance changing with time as a contact resistance model according to the initial breakdown area and unit contact resistance.

9. A terminal device, characterized in that: The method comprises a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, wherein the processor implements the contact resistance modeling method according to any one of claims 1 to 7 when executing the computer program.

10. A storage medium, characterized in that: The storage medium includes a stored computer program, wherein when the computer program is executed, the device where the storage medium is located is controlled to execute the contact resistance modeling method according to any one of claims 1 to 7.

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