CN113190972B - Conductor temperature calculation method of cable joint and body based on micro-elements - Google Patents
Conductor temperature calculation method of cable joint and body based on micro-elements Download PDFInfo
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Abstract
The invention discloses a conductor temperature calculation method of a cable joint and a body based on a micro element, which comprises the following steps: an axial thermal path model is constructed, the cable connector is divided into a plurality of sections of subsection sections by the axial thermal path model according to the insulation thickness of each structure of the cable connector, and each section of subsection section of the cable connector is respectively divided into a plurality of sections of micro-elements in the axial direction by taking the center of a crimping pipe of the cable connector as an original point; and the cable body is divided into a plurality of sections of micro-elements along the axial direction; and based on the axial thermal circuit model, obtaining the conductor temperatures of the cable joint and the cable body through iterative calculation by inputting the surface temperatures of the cable joint and the cable body. Compared with the prior art, the method has the advantages that the calculation result is more accurate, the calculation result can be obtained only by inputting the surface temperatures of the cable connector and the body in the model, the time and the energy are less, and the problem of difficult sensor arrangement is solved.
Description
Technical Field
The invention relates to the technical field of cable joint conductor temperature measurement, in particular to a conductor temperature calculation method of a cable joint and a cable joint body based on a micro element.
Background
With the rapid development of urban power grid systems, high-voltage power cables have been widely used in power transmission networks, and the number of intermediate connectors for connecting cables at two ends is increasing. The current-carrying capacity of the cable is closely related to the temperature of the conductor, and practical experience proves that the temperature of the conductor of the cable joint is far higher than that of the conductor of the cable under the same load level due to the thick insulation of the cable joint and the contact resistance in the cable joint, so that the current-carrying capacity of the cable is limited.
At present, the conductor temperature of the cable joint or the body is generally obtained by adopting an analytical method and a numerical algorithm. The analytical method is based on the electricity-heat analogy to establish a thermal circuit model, utilizes temperature sensors such as a thermocouple and the like to monitor and obtain the surface temperature or the environment temperature, inputs the surface temperature or the environment temperature into the thermal circuit model, and finally calculates to obtain the conductor temperature; the numerical calculation method is to use software such as finite elements to build a thermal field model of the cable joint and the body and apply corresponding boundary conditions to calculate and obtain a temperature distribution result. And optical fibers are also built in the cable in part of engineering, so that the online monitoring of the cable conductor is realized. However, the applicant has found that the current method has the following drawbacks:
the existing numerical calculation method carries out simulation operation by means of software such as finite elements, has a complex modeling process and is not beneficial to direct application by non-professional personnel;
The existing cable joint hot circuit model calculates the temperature distribution, the calculation precision is low, and the error between the calculation result and the actual conductor temperature is large;
the difficulty of realizing real-time online monitoring of the temperature of the cable joint conductor is high, the accuracy of a temperature monitoring result under a strong electromagnetic interference environment is difficult to guarantee, and the improvement of the current-carrying capacity of a cable line is not facilitated.
Disclosure of Invention
The present invention is directed to solving at least one of the problems of the prior art. Therefore, the invention provides a conductor temperature calculation method of a cable joint and a body based on a micro element, and compared with the prior art, the calculation result is more accurate.
The invention provides a conductor temperature calculation method of a cable joint and a cable body based on a micro element, which is used for calculating the conductor temperature of the cable joint and the cable body adjacent to the cable joint and comprises the following steps:
an axial thermal circuit model is built, the cable connector is divided into a plurality of subsection sections by the axial thermal circuit model according to the insulation thickness of each structure of the cable connector, and each subsection section of the cable connector is divided into a plurality of micro-elements respectively along the axial direction by taking the center of a crimping pipe of the cable connector as an original point; the cable body is divided into a plurality of micro-elements along the axial direction;
And based on the axial thermal circuit model, iteratively calculating to obtain the conductor temperatures of the cable joint and the cable body by inputting the surface temperatures of the cable joint and the cable body.
According to the embodiment of the invention, at least the following technical effects are achieved:
(1) according to the method, the cable joint and the body are divided into a plurality of tiny 'elements' according to the structural characteristics of the cable joint, so that the radial thermal resistance obtained through calculation is more accurate in the iterative calculation process based on the axial thermal circuit model. The method can fully embody the structural characteristics of the cable joint, and the total radial thermal resistance is calculated more accurately, so that the final conductor temperature calculation result is more accurate.
(2) The axial hot-circuit model of the cable joint and the body can be realized through numerical software such as matlab and the like, the result of the conductor temperature can be output only by inputting the surface temperature of the cable joint and the body in the model, and the time and the energy required by applying finite element software are greatly reduced.
(3) According to the method, the conductor temperature can be calculated by arranging the sensors on the surfaces of the cable connector and the body and inputting the monitored surface temperature into the model, so that the problem that the temperature sensors are difficult to arrange on the conductor is solved.
In a second aspect of the invention, a conductor temperature calculation device for a micro-element based cable joint and body is provided, which comprises at least one control processor and a memory for communication connection with the at least one control processor; the memory stores instructions executable by the at least one control processor to enable the at least one control processor to perform a method of calculating conductor temperature of a micro-element based cable joint and body according to the first aspect of the invention.
In a third aspect of the present invention, a computer-readable storage medium is provided, which stores computer-executable instructions for causing a computer to perform a method for calculating conductor temperature of a micro-element based cable joint and a body according to the first aspect of the present invention.
Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
Drawings
The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:
Fig. 1 is a schematic flow chart of a method for calculating conductor temperatures of a micro-element-based cable joint and a body according to this embodiment;
FIG. 2 is a flowchart of an implementation of step S200 in FIG. 1;
FIG. 3 is an axial thermal path model of the cable connector and body provided in this embodiment;
FIG. 4 is a comparison diagram of the calculated results of the conductors of the cable joint and the body according to three different methods provided in this embodiment;
fig. 5 is a schematic structural diagram of the conductor temperature calculating device of the micro element-based cable joint and the body according to this embodiment.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention.
A first embodiment;
referring to fig. 1 to 3, an embodiment of the present invention provides a conductor temperature calculation method for a micro-element-based cable joint and a body, for calculating conductor temperatures of the cable joint and the cable body adjacent to the cable joint, including the following steps:
S100, constructing an axial thermal circuit model, dividing the cable joint into a plurality of sections of sectional intervals according to the insulation thickness of each structure of the cable joint by the axial thermal circuit model, and respectively dividing each section of sectional interval of the cable joint into a plurality of sections of micro-elements in the axial direction by taking the center of a crimping pipe of the cable joint as an original point; and the cable body is divided into a plurality of sections of micro-elements along the axial direction.
It should be noted that, because the structure of the cable joint is axisymmetric, and the long end and the short end have similar structures, and there is only a difference in length, for convenience of description, only the cable joint with the quarter structure is taken as an example to build an axial thermal circuit model, and the long end is taken as an example in this embodiment. When an axial thermal circuit model is built, firstly, according to the structural characteristics of a cable connector, the center of a crimping pipe is used as an original point, the center is divided into two ends according to the insulation thickness, and in each section interval, each section is further divided into a plurality of micro-elements along the axial direction by using the idea of the micro-elements. The cable body is the same reason, because the structure of the cable body is all consistent with the direction from the head end of the cable body to the tail end of the cable body, the cable body is divided into a plurality of infinitesimal elements within a certain length, wherein the head end of the cable body is the end of the cable body adjacent to the cable joint.
An axial thermal path model constructed in the embodiment is shown in fig. 3, and infinitesimal 1-j represent long-end crimping pipe sections; the micro elements j + 1-k represent the main insulation section of the long-end cable joint; the infinitesimal k + 1-m represents a long-end copper shell thin layer section; the infinitesimal m + 1-n represents the main section of the long-end cable. It should be noted that, in this embodiment, a 110kV pass-through cable connector is taken as an example, but the scope of the present invention is not limited thereto, for example, a cable connector of this model includes a copper shell thin layer, and a cable connector of some models on the market does not include a copper shell thin layer, but those skilled in the art can adapt to an actual cable connector object based on this embodiment. It should be noted that, in this embodiment, the cable joint is divided into a plurality of segment intervals, such as the long-end crimping pipe section, the long-end cable joint main insulation section, and the long-end copper shell thin layer section in fig. 3, according to the structure of the cable joint, and each segment interval is divided into a plurality of micro-elements.
In FIG. 3, model Δ T h1 ～ΔT hj Represents the radial thermal resistance of the high-voltage shielding pipe; delta T m1 ～ΔT mk The radial thermal resistance of the main insulating silicon rubber of the cable joint is shown; delta T p1 ～ΔT pm Represents the radial thermal resistance of the PVC belt; delta T s1 ～ΔT sm The radial thermal resistance of the sealant is shown; delta T c1 ～ΔT cm Represents the radial thermal resistance of the copper shell; delta T i(j+1) ～ΔT in The radial thermal resistance of the main insulation XLPE of the cable is shown; delta T w(m+1) ～ΔT wn Represents the radial thermal resistance of the water-blocking tape; delta T sh(+1) ～ΔT shn Represents the radial thermal resistance of the aluminum jacket; delta T o(m+1) ～ΔT on Represents the radial thermal resistance of the outer jacket; delta T x1 ～ΔT xn Represents the axial infinitesimal thermal resistance of the copper core; theta 1 ′～θ m ' denotes the surface temperature of the cable joint; theta m+1 ′～θ n ' represents the surface temperature of the cable body; theta 1 ～θ m Represents the conductor temperature of the cable joint; theta m+1 ～θ n Represents the conductor temperature of the cable body; delta Q r1 ～ΔQ rn Representing conductor joule loss.
S200, obtaining conductor temperatures of the cable joint and the cable body through iterative calculation by inputting surface temperatures of the cable joint and the cable body based on the axial thermal circuit model.
As shown in fig. 2, as a preferred embodiment, step S200 specifically includes:
s201, calculating the radial thermal resistance and the axial thermal resistance of each infinitesimal element in the axial thermal circuit model;
the cable joint and the body (except for special statement, the cable body is referred to as the body in the embodiment) can be approximated as a round through thick-walled structure, and the radial total thermal resistance Δ T of the cable joint and the body in the s-th section can be calculated according to the following formula ys And axial thermal resistance Δ T of conductor between adjacent elements xs . The radial total thermal resistance is obtained by solving the superposition of the radial thermal resistances of all layers:
wherein r represents the number of layers,. DELTA.Z s Denotes the length of the s-th section of the element, λ i Denotes the thermal conductivity, λ, of the ith layer material c Denotes the thermal conductivity, r, of the copper core c Denotes the radius of the copper core, d i Denotes the inner diameter of the i-th layer, d i+1 Indicating the outer diameter of the ith layer. It should be noted that, since the structures of all the microelements in each segment of the segment interval are the same, after the radial thermal resistance and the axial thermal resistance of each segment of the microelements are obtained, the radial thermal resistance and the axial thermal resistance of each segment of the microelements in each segment of the segment interval can be naturally obtained.
S202, calculating an initial value of the axial thermal circuit model;
assuming the conductor initial temperature of each micro-element of the cable joint and the bodyIs theta (0) At this time, for the three-dimensional axial thermal path model of the cable joint shown in fig. 2, the axial heat flow between the micro elements is 0, and the conductor loss is calculated as follows:
it should be noted that, since the 110kV straight-through cable joint is selected in this embodiment, the cable joint is divided into four segments, but the number of the segment intervals is different according to the model of the actually selected cable joint, so that the above formula can be adaptively adjusted according to the actual situation, and will not be described repeatedly.
In the above formula, I represents the current of the conductor, R represents the ac resistance of the conductor, α represents the temperature coefficient of resistance of the conductor, and α of standard soft copper is 0.0039. As can be seen from the heat flow balance, the incoming heat flow is consistent with the outgoing heat flow, and the initial temperature of each micro-element is assumed to be the same in the initial process, which results in the axial heat flow being 0, so the conductor temperature of each micro-element in the initialization process is completely determined by the conductor loss, and the conductor temperature is calculated as follows:
in the above-mentioned formula, the compound has the following structure,
the surface temperature of the s-th section of the element is shown.
And taking the conductor temperature obtained by the calculation as an initial value in the first iteration process of the axial thermal circuit model.
S203, calculating heat flows of the axial heat path model, wherein the heat flows of the axial heat path model comprise inflow heat flows and outflow heat flows.
After the initialization in step S202, the conductor temperatures of the micro-elements in the axial thermal path model are different, and calculation is performed from the end of the model, which is the end of the long-end cable body, to the beginning of the model, which is the center of the crimp tube of the cable joint. The iteration rule is as follows: when the next conductor temperature value is calculated, the calculation result of the conductor temperature at the previous time is taken as a reference, and repeated iterative calculation is carried out until convergence.
S2031, calculating the conductor loss of each infinitesimal element, as shown in the following formula, wherein i is 1,2,3 … …; i represents the number of iterations;
S2032, calculating the axial heat flow flowing into each micro element;
when calculating the axial heat flow flowing into the s-th element, the temperature results of the s-1 th element and the s-th element are used. The iterative calculation is carried out from the terminal end to the initial end of the model, the temperature of the s-th element and the previous conductor is not updated and is still kept as the temperature result theta obtained by the last iterative calculation (i) . Thus, the axial heat flow Δ Q into the infinitesimal x1 The temperature from the last iteration is calculated as follows:
wherein the content of the first and second substances,
representing the axial heat flow into the s-th bin at i +1 iterations,
denotes the conductor temperature, Δ T, of the s-1 th infinitesimal element at the i-th iteration x1 ,ΔT x2 ,ΔT x3 ,ΔT x4 Respectively representing the conductor axial thermal resistance between adjacent micro-elements of the 1 st, 2 nd, 3 rd and 4 th segment intervals.
S2033, calculating the axial heat flow of each micro element;
when calculating the axial heat flow flowing out of the s-th element, the temperature results of the s-th element and the s + 1-th element are used. As can be seen from the iteration sequence, the conductor temperature of each micro-element after the micro-element is updated, i.e. the temperature of the s +1 th to the n-th micro-elements is theta (i+1) While the temperatures of the 1 st to s th micro-elements are still the result theta obtained by the last iteration calculation (i) . Therefore, to speed up the iterative convergence, the axial heat flow Δ Q out of the bin is calculated x2 The following formula can be used:
wherein the content of the first and second substances,
representing the axial heat flow out of the s-th section of infinitesimal at i +1 iterations,
the conductor temperature of the (s + 1) th section of infinitesimal at the (i + 1) th iteration is shown.
It should be noted that, in the calculation process of the axial thermal path model, relevant constraints need to be applied to the axial thermal flow:
(1) in the calculation process, in order to ensure the unidirectionality of the axial heat flow, a constraint condition 1 is set, wherein the axial heat flow is more than or equal to 0, namely delta Q xs Not less than 0, if the s-th axial heat flow is less than 0, let Δ Q xs ＝0；
(2) In the first few iterative calculation processes, the phenomenon that the inflow axial heat flow is far larger than the outflow axial heat flow or the outflow axial heat flow is far larger than the inflow axial heat flow occurs in part of the nodes, so that the temperature is increased or decreased, and the trend that the actual conductor temperature is monotonically decreased from the center to the two ends is not met. Therefore, applying constraint 2 to the axial heat flow as shown below limits the magnitude of the axial heat flow:
Wherein, K 1 Represents the reduction times and has the value range of K 1 (the most preferred embodiment is 1.1). Until Δ Q is satisfied x1s ′-ΔQ x2s ≤K 2 Or Δ Q x2s ′-ΔQ x1s ≤K 2 Until the conditions of (1). K 2 Representing a constraint coefficient with a value range of 0<K 2 <1, limiting the magnitude of the axial heat flow, preventing sharp increases or decreases in temperature.
S204, calculating conductor temperatures of the cable joint and the body;
under the action of axial heat flow, the conductor temperature of each micro element of the cable joint and the body is determined by the combined action of radial heat flow and axial heat flow. Based on the heat flow and the thermal resistance obtained by the above calculation, the conductor temperature is obtained by the following calculation formula:
wherein the content of the first and second substances,
represents the conductor temperature of the s-th section of micro-element at the (i + 1) th iteration,
denotes the surface temperature, Δ T, of the s-th element y1 ,ΔT y2 ,ΔT y3 ,ΔT y4 Respectively representing the radial thermal resistance of the segment intervals of 1 st, 2 nd, 3 rd and 4 th.
To facilitate understanding of the iterative process, a simple example is listed based on equations (5), (6), (7):
for example, the 10 th point for the 3 rd iteration is now performed (the head end is named 1 st point). When calculating the conductor loss, the conductor temperature of the 10 th point obtained by the 2 nd iteration needs to be used, when calculating the inflow axial heat flow, the conductor temperature of the 9 th point and the 10 th point obtained by the 2 nd iteration needs to be used, and when calculating the outflow axial heat flow, the conductor temperature of the 10 th point obtained by the 2 nd iteration and the conductor temperature of the 11 th point obtained by the 3 rd iteration need to be used. Because each calculated point may be different, the conductor loss, the axial heat flow and finally the conductor temperature are changed.
And S205, judging the conductor temperature convergence of the cable joint and the body.
Based on the conductor temperature calculated in step S204, the difference between the i +1 st calculation result and the i-th calculation result of each infinitesimal element is successively compared, and if the conductor temperature of each infinitesimal element satisfies the determination condition of the following formula, iteration converges; otherwise, the process from step S203 to step S204 is repeated until a convergence condition is reached, which is as follows:
wherein 0.1 is a threshold, certainly, the threshold can be adjusted, and when 0.1 is taken, experiments show that convergence can be achieved through 6 to 7 iterations, and selecting 0.1 is a better choice, and the calculation accuracy of the result is high.
The embodiment of the method has the following beneficial effects:
(1) compared with the method proposed by the Egypt scholars M.M.Abdel, the method provided by the Egypt scholars assumes the cable joint to be a uniform and regular structural body, directly analyzes one infinitesimal of the cable joint, and obtains the expression of the conductor temperature by using the idea of locally solving the whole body. However, the cable connector has a complex structure, and the structure and material characteristics of different parts are different, so that the cable connector cannot be directly regarded as a regular whole. The method divides the cable joint and the body into a plurality of tiny 'elements' according to the structural characteristics of the cable joint, and calculates the radial thermal resistance of each infinitesimal, and the radial thermal resistance obtained by the method is more accurate because the total radial thermal resistance is the sum of the radial thermal resistances of all layers, and the difference of the structural and material characteristics can cause the radial thermal resistances of all layers to be inconsistent, and finally causes the difference of the total radial thermal resistance. The method can fully embody the structural characteristics of the cable joint, and the total radial thermal resistance is calculated more accurately so that the final calculation result is more accurate. Referring to the experimental result provided by the second embodiment, the error between the temperature value calculated by the method and the temperature value obtained by the simulation result is smaller than that of the prior art, and the calculation accuracy is effectively improved.
(2) The axial hot-circuit model of the cable joint and the body can be realized through numerical software such as matlab and the like, the result of the conductor temperature can be output only by inputting the surface temperature of the cable joint and the body in the model, and the time and the energy required by applying finite element software are greatly reduced.
(3) According to the method, the conductor temperature can be calculated by arranging the sensors on the surfaces of the cable connector and the body and inputting the monitored surface temperature into the model, so that the problem that the temperature sensors are difficult to arrange on the conductor is solved.
A second embodiment;
to verify the effectiveness of embodiments of the present invention, a set of experimental data is provided below:
to be adapted to 110kV 630mm 2 In a straight-through joint of a cable, the current-carrying capacity of the line is 1000A for example, the axial thermal circuit model provided by the embodiment of the method is used for calculating the temperature of the conductor, and the theoretical calculation result is compared with the simulation calculation result and the result of the joint temperature calculation method provided by the amateur of egypt, m.m.abdel, and the result is shown in fig. 4. In the experiment, each section is a micro sectionThe distances of the elements are exemplified as follows:
the micro-element lengths of the short-end crimping pipe, the short-end main insulator, the short-end copper shell thin layer and the short-end body are respectively 0.098m, 0.071m, 0.075m and 0.1257 m; the micro-element lengths of the long-end crimping pipe, the long-end main insulator, the long-end copper shell thin layer and the long-end body are 0.098m, 0.082m, 0.076m and 0.1304m respectively.
As shown in fig. 4, the calculation result of the axial thermal circuit model proposed by the embodiment of the method is slightly lower than the simulation result, but the axial thermal circuit model and the simulation result have better consistency in general, the maximum temperature difference does not exceed 2 ℃, and the error range of the engineering practice is met. The difference between the cable joint temperature calculation method proposed by Egypt scholars and the simulation result is large, and the calculation difference between the cable joint temperature calculation method and the simulation result is as high as 20 ℃. Therefore, the axial thermal circuit model provided by the embodiment of the method can reduce the calculation error of the existing method and improve the calculation accuracy.
A third embodiment;
referring to fig. 5, an embodiment of the present invention provides a conductor temperature calculating device of a micro element-based cable connector and body, which may be any type of intelligent terminal, such as a mobile phone, a tablet computer, a personal computer, etc.
Specifically, the conductor temperature calculation device of the micro-element-based cable joint and the body comprises: one or more control processors and memory. The control processor and memory may be connected by a bus or other means.
The memory, which is a non-transitory computer readable storage medium, may be used to store non-transitory software programs, non-transitory computer executable programs, and modules, such as program instructions/modules corresponding to the conductor temperature calculation device of the micro-component based cable joint and body in embodiments of the present invention. The control processor executes various functional applications and data processing of the conductor temperature calculation system of the cable joint by running the non-transitory software program, instructions and modules stored in the memory, namely, the method for calculating the conductor temperature of the cable joint and the body based on the micro-elements based on the template sequence of the embodiment of the method is realized.
The memory may include a storage program area and a storage data area, wherein the storage program area may store an operating system, an application program required for at least one function; the storage data area may store data created from use of a conductor temperature calculation system of the cable joint, and the like. Further, the memory may include high speed random access memory, and may also include non-transitory memory, such as at least one disk storage device, flash memory device, or other non-transitory solid state storage device. In some embodiments, the memory optionally includes memory remotely located from the control processor, and these remote memories may be connected to the micro-element based cable connector and body conductor temperature calculation device via 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 one or more modules are stored in the memory and, when executed by the one or more control processors, perform a method of calculating conductor temperatures of a micro-element based cable joint and body based on a template sequence of the above-described method embodiments.
Embodiments of the present invention further provide a computer-readable storage medium, where computer-executable instructions are stored, and executed by one or more control processors, so as to enable the one or more control processors to execute a method for calculating conductor temperatures of a micro-element-based cable joint and a body based on a template sequence in the method embodiments.
The above-described embodiments of the apparatus are merely illustrative, and the units described as separate parts may or may not be physically separate, may be located in one place, or may be distributed over a plurality of network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of this embodiment.
Through the above description of the embodiments, those skilled in the art can clearly understand that the embodiments can be implemented by software plus a general hardware platform. Those skilled in the art will appreciate that all or part of the processes of the methods of the above embodiments may be implemented by hardware related to instructions of a computer program, which may be stored in a computer readable storage medium, and when executed, may include the processes of the embodiments of the methods described above. The storage medium may be a magnetic disk, an optical disk, a Read Only Memory (ROM), a Random Access Memory (RAM), or the like.
In the description herein, references to the description of the term "one embodiment," "some embodiments," "an illustrative embodiment," "an example," "a specific example," or "some examples" or the like mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
While embodiments of the invention have been shown and described, it will be understood by those of ordinary skill in the art that: various changes, modifications, substitutions and alterations can be made to the embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.
Claims (7)
1. A conductor temperature calculation method of a cable joint and a body based on a micro element is characterized in that the method is used for calculating the conductor temperature of the cable joint and the cable body adjacent to the cable joint and comprises the following steps:
an axial thermal path model is constructed, the cable joint is divided into a plurality of sections of subsection sections by the axial thermal path model according to the insulation thickness of each structure of the cable joint, and each section of subsection section of the cable joint is divided into a plurality of sections of micro-elements respectively along the axial direction by taking the center of a crimping pipe of the cable joint as an original point; the cable body is divided into a plurality of sections of micro-elements uniformly along the axial direction;
iteratively calculating to obtain conductor temperatures of the cable joint and the cable body by inputting surface temperatures of the cable joint and the cable body based on the axial thermal circuit model; wherein, the step of iterative computation of the axial thermal circuit model comprises:
Calculating an initial iteration value of the conductor temperature of each section of the micro element in the axial thermal circuit model based on the surface temperature of each section of the micro element of the cable joint and the cable body, the radial total thermal resistance of each section of the micro element of the cable joint and the cable body, and the conductor loss of each section of the micro element of the cable joint and the cable body calculated by preset conductor temperature;
iteratively calculating conductor losses of each section of the micro-elements of the cable joint and the cable body, axial heat flows of each section of the micro-elements of the cable joint and the cable body, and conductor temperatures of each section of the micro-elements of the cable joint and the cable body based on the initial iterative values of the axial thermal path model and the surface temperatures of each section of the micro-elements of the cable joint and the cable body:
wherein, the
Representing the conductor loss of the s-th section of micro-element at the (I + 1) th iteration, wherein I represents the current of the conductor, R represents the alternating current resistance of the conductor, alpha represents the temperature coefficient of resistance of the conductor, and
represents the conductor temperature of the s-th section of micro-element at the i-th iteration, and the delta z j Representing the infill length of the j-th segment of the segmented interval, said
Representing the axial heat flow at i +1 iterations of the flow into the s-th bin 
Represents the conductor temperature of the s-1 th section of micro-element at the i-th iteration, and the delta T xj Represents the conductor axial thermal resistance between adjacent microelements of the j section subsection interval
Representing the axial heat flow at i +1 iterations of the outgoing s-th bin infinitesimal
Represents the conductor temperature of the (s + 1) th section of micro-element at the (i + 1) th iteration
Represents the conductor temperature of the s-th section of micro-element at the (i + 1) th iteration
Denotes the surface temperature of the s-th infinitesimal, the Δ T y1 Denotes the radial thermal resistance of the first segment of the segment interval, said Δ T yj Representing the radial thermal resistance of the j section segmentation interval;
if the conductor temperatures of each section of the micro element of the cable joint and the cable body both meet a convergence condition, the conductor temperatures of the cable joint and the cable body are output, and the convergence condition comprises:
wherein the S1 represents a threshold value.
2. The method of claim 1, wherein S1 is set to 0.1.
3. The method of claim 1, wherein the formula for calculating the total radial thermal resistance of each section of the micro-element in the cable joint and the cable body comprises:
Wherein, the Δ T ys The radial total thermal resistance of the s-th section of micro-element is represented, the r represents the number of layers of the s-th section of micro-element, and the Delta Z s Denotes the length of the s-th infinitesimal, said λ i Denotes the thermal conductivity of the i-th layer material, d i Denotes the inner diameter of the i-th layer of material, d i+1 The outer diameter of the ith layer of material is indicated.
4. The method of claim 2, further comprising the steps of:
if the conductor temperature of at least one of the cable joint and the cable body does not meet the convergence condition, calculating the conductor loss of each section of the cable joint and the cable body, the axial heat flow of each section of the cable joint and the cable body and the conductor temperature of each section of the cable joint and the cable body again according to the conductor temperature obtained by the iteration until the conductor temperatures of each section of the cable joint and the cable body meet the convergence condition, and outputting the conductor temperatures of the cable joint and the cable body.
5. The method of claim 1 wherein the axial length of each section of said segmented region is different for each corresponding micro element.
6. A conductor temperature calculation equipment of cable joint and body based on infinitesimal, its characterized in that: comprises at least one control processor and a memory for communicative connection with the at least one control processor; the memory stores instructions executable by the at least one control processor to enable the at least one control processor to perform a method of conductor temperature calculation for a micro-element based cable joint and body as claimed in any one of claims 1 to 5.
7. A computer-readable storage medium characterized by: the computer-readable storage medium stores computer-executable instructions for causing a computer to perform a method of calculating conductor temperatures of a micro-element based cable joint and body as claimed in any one of claims 1 to 5.
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