Cable temperature detection method and device considering dynamic parameter characteristics and storage medium

Abstract

The invention discloses a cable temperature detection method and device considering dynamic parameter characteristics and a storage medium. The method comprises the steps that a cable is converted into an equivalent thermal circuit model; the structure of the thermal circuit model comprises a conductor layer, a plurality of insulating layers, an air gap layer, a metal sheath and an outer sheath. Substituting the thermal resistance of the air gap layer at the previous moment into a heat conduction equation of the thermal model to obtain the temperature of each layer structure of the thermal circuit model at the current moment; calculating the expansion amount of the plurality of insulating layers at the current moment according to the temperature of each layer structure of the thermal circuit model at the current moment; calculating the expansion degree of the plurality of insulating layers from the air gap layer to the metal sheath according to the expansion amount to obtain the adaptability; calculating the thermal resistance of the air gap layer at the current moment according to the matching degree and the expansion amount; and outputting the temperature of each layer of structure in the thermal circuit model when the appointed moment is reached. According to the embodiment, the accuracy of thermal evaluation is effectively improved, a data basis is provided for formulating an accurate cable temperature guidance load scheduling strategy, and the cable power transmission potential is fully excavated.

Description

Technical Field

[0001] The present invention relates to the field of electric power technology, and in particular to a cable temperature detection method, device and storage medium taking dynamic parameter characteristics into consideration. Background Art

[0002] With the large-scale grid connection of various new energy sources, led by wind, solar and photovoltaic power generation, the volatility of new energy generation has brought challenges to power transmission. Therefore, the ability of cables to dynamically transmit power should be evaluated, and then an effective load scheduling strategy should be formed to utilize existing power assets to cope with the impact of new energy.

[0003] One of the main factors affecting the power transmission capacity of cables is cable temperature. Accurate and rapid cable thermal assessment can provide important information for the formulation of cable load scheduling strategies, maximize the potential transmission capacity of cables, cope with the volatility of new energy loads, and improve asset utilization.

[0004] At present, thermal evaluation of cables mostly uses the thermoelectric equivalent method, which starts from the internal structure of the cable and models the insulation layer in layers to perform steady-state thermal evaluation of the cable.

[0005] However, due to manufacturing process problems, there will be an air gap inside the cable, which affects heat transfer and causes large errors in the steady-state thermal evaluation of the cable. Summary of the Invention

[0006] In view of this, the present invention provides a cable temperature detection method, device and storage medium that consider dynamic parameter characteristics, so as to account for the influence of air gap and improve the accuracy of steady-state thermal evaluation of the cable.

[0007] A first aspect of the present invention provides a cable temperature detection method considering dynamic parameter characteristics, comprising:

[0008] Converting the cable into an equivalent thermal circuit model; the structure of the thermal circuit model includes a conductor layer, multiple insulation layers, an air gap layer, a metal sheath and an outer sheath;

[0009] Substituting the thermal resistance of the air gap layer at the previous moment into the heat conduction equation of the thermal model to obtain the temperature of each layer structure of the thermal circuit model at the current moment;

[0010] Calculating the expansion amount of the plurality of insulating layers at the current moment according to the temperature of each layer structure of the thermal circuit model at the current moment;

[0011] Calculating the expansion degree of the plurality of insulating layers from the air gap layer to the metal sheath according to the expansion amount to obtain a fit degree;

[0012] Calculating the thermal resistance of the air gap layer at a current moment based on the degree of fit and the amount of expansion, returning to the step of substituting the thermal resistance of the air gap layer at a previous moment into the heat conduction equation of the thermal circuit model to obtain the temperature of each layer structure of the thermal circuit model at the current moment;

[0013] When the specified time is reached, the temperature of each layer structure in the thermal circuit model is output.

[0014] A second aspect of the present invention provides a cable temperature detection device taking into account dynamic parameter characteristics, comprising:

[0015] A thermal circuit model conversion module is used to convert the cable into an equivalent thermal circuit model; the structure of the thermal circuit model includes a conductor layer, multiple insulation layers, an air gap layer, a metal sheath and an outer sheath;

[0016] a temperature calculation module, configured to substitute the thermal resistance of the air gap layer at a previous moment into the heat conduction equation of the thermal circuit model to obtain the temperature of each layer structure of the thermal circuit model at a current moment;

[0017] an expansion amount calculation module, configured to calculate the expansion amount of the plurality of insulating layers at a current moment based on the temperature of each layer structure of the thermal circuit model at a current moment;

[0018] a fit calculation module, configured to calculate the expansion degree of the plurality of insulating layers from the air gap layer to the metal sheath according to the expansion amount, to obtain a fit;

[0019] a thermal resistance calculation module, configured to calculate the thermal resistance of the air gap layer at a current moment based on the degree of fit and the amount of expansion, and return to execute the temperature calculation module;

[0020] The temperature output module is used to output the temperature of each layer structure in the thermal circuit model when a specified time is reached.

[0021] A third aspect of the present invention provides an electronic device, comprising:

[0022] at least one processor; and

[0023] a memory communicatively connected to the at least one processor; wherein,

[0024] The memory stores a computer program executable by the at least one processor, and the computer program is executed by the at least one processor so that the at least one processor can execute the cable temperature detection method considering dynamic parameter characteristics as described in the first aspect above.

[0025] A fourth aspect of the present invention provides a computer-readable storage medium storing a computer program. When the computer program is executed by a processor, the method for detecting cable temperature considering dynamic parameter characteristics as described in the first aspect above is implemented.

[0026] A fifth aspect of the present invention provides a computer program product, comprising a computer program. When the computer program is executed by a processor, the method for detecting cable temperature considering dynamic parameter characteristics as described in the first aspect above is implemented.

[0027] In this embodiment, the cable is converted into an equivalent thermal circuit model; the structure of the thermal circuit model includes a conductor layer, multiple insulation layers, an air gap layer, a metal sheath, and an outer sheath; the thermal resistance of the air gap layer at the previous moment is substituted into the heat conduction equation of the thermal model to obtain the temperature of each layer structure of the thermal circuit model at the current moment; the expansion of the multiple insulation layers at the current moment is calculated based on the temperature of each layer structure of the thermal circuit model at the current moment; the expansion degree of the multiple insulation layers from the air gap layer to the metal sheath is calculated based on the expansion amount to obtain the fit; the thermal resistance of the air gap layer at the current moment is calculated based on the fit and expansion amount; and at the specified moment, the temperature of each layer structure in the thermal circuit model is output. This embodiment takes into account the thermal expansion of the insulation layer and the thermal resistance correction of the air gap layer to perform thermal evaluation of the cable, effectively improving the accuracy of the thermal evaluation and providing a data basis for accurately guiding the formulation of load scheduling strategies based on cable temperature, fully tapping the transmission potential of the cable, improving the asset utilization rate of the transmission system, and addressing the challenges brought by the volatility of renewable energy power generation.

[0028] It should be understood that the content described in this section is not intended to identify the key or important features of the embodiments of the present invention, nor is it intended to limit the scope of the present invention. Other features of the present invention will become readily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0030] Figure 1 This is a flowchart of a cable temperature detection method considering dynamic parameter characteristics provided by Example 1 of the present invention.

[0031] Figure 2 It is a structural schematic diagram of a thermal circuit model provided in Example 1 of the present invention.

[0032] Figure 3This is a schematic diagram of thermal expansion of a cable provided in Example 1 of the present invention.

[0033] Figure 4 This is a flow chart of a cable temperature detection method considering dynamic parameter characteristics provided by the second embodiment of the present invention.

[0034] Figure 5 This is an example diagram of the comparison between error and time provided in the second embodiment of the present invention.

[0035] Figure 6 This is a structural diagram of a cable temperature detection device taking dynamic parameter characteristics into consideration, provided in a third embodiment of the present invention.

[0036] Figure 7 This is a structural diagram of an electronic device provided in Example 4 of the present invention. DETAILED DESCRIPTION

[0037] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described 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 making creative efforts should fall within the scope of protection of the present invention.

[0038] It should be noted that the terms "first", "second", etc. in the description and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can cover sequential implementations other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0039] Example 1

[0040] See also Figure 1 , shows a flow chart of a cable temperature detection method considering dynamic parameter characteristics provided by the first embodiment of the present invention. The method can be executed by a cable temperature detection device considering dynamic parameter characteristics. The cable temperature detection device considering dynamic parameter characteristics can be implemented in the form of hardware and / or software. The cable temperature detection device considering dynamic parameter characteristics can be configured in an electronic device. Figure 1 As shown, the method includes:

[0041] Step 101: Convert the cable into an equivalent thermal circuit model.

[0042] In this embodiment, an equivalent thermal circuit model is established for the cable body in combination with the internal heat transfer process of the air-gap cable, forming a thermal-mechanical multi-field coupling model to analyze the dynamic thermal behavior inside the air-gap cable when considering the thermal expansion of the insulation.

[0043] Among them, Figure 2 As shown, the structure of the thermal circuit model includes a conductor layer (such as a copper conductor), multiple insulation layers, an air gap layer, a metal sheath (such as an aluminum sheath, etc.) and an outer sheath.

[0044] The insulation layer (including inner and outer shielding and wrapping tape) can be modeled in layers using the equal thickness method, which can effectively improve the accuracy of the thermal circuit model. By constructing the thermal circuit model, a preliminary analysis of the dynamic thermal evaluation of cables with air gaps is achieved.

[0045] In general, the heat capacity of the conductor layer is:

[0046]

[0047] Where Q0 is the heat capacity of the conductor layer, δ0 is the volume heat capacity of the conductor layer, and D0 is the outer diameter of the conductor layer;

[0048] The thermal resistance of each insulation layer is:

[0049]

[0050] Among them, T 1-i is the thermal resistance of the i-th insulation layer, λ 1-i is the thermal conductivity of the i-th insulating layer, D 1-i is the outer diameter of the i-th insulation layer, D 1-(i-1) is the outer diameter of the i-1th insulating layer.

[0051] The heat capacity of the insulating layer is:

[0052]

[0053] Among them, Q 1-i is the heat capacity of the i-th insulating layer, δ 1-i is the volume heat capacity of the i-th insulating layer, D 1-i is the outer diameter of the i-th insulation layer, D 1-(i-1) is the outer diameter of the i-1th insulating layer.

[0054] Step 102: Substitute the thermal resistance of the air gap layer at the previous moment into the heat conduction equation of the thermal circuit model to obtain the temperature of each layer structure of the thermal circuit model at the current moment.

[0055] The influence of the air gap layer on heat transfer should be taken into account in the steady-state thermal evaluation of the cable. Moreover, since the thermal expansion of the insulation layer is sensitive to temperature changes, the thermal parameters of the air gap layer (such as thermal resistance) should be equivalently corrected in combination with the thermal expansion of the insulation layer.

[0056] In this embodiment, considering that the thermal resistance of the air gap layer changes dynamically during the thermal expansion of the insulating layer, multiple moments can be divided in time, and the interval between two adjacent moments is a preset step size Δt, that is, t1=t0+Δt, where t1 is the current moment and t0 is the previous moment.

[0057] The thermal resistance of the air gap layer is iteratively updated in real time at multiple moments to invert the thermal expansion process of the insulation layer, thereby accurately reflecting the complex heat transfer behavior inside the cable.

[0058] At the current moment, the thermal resistance of the air gap layer at the previous moment can be substituted into the heat conduction equation of the thermal circuit model. In the process of simulating heat conduction, the temperature of each layer structure of the thermal circuit model at the current moment can be obtained, thereby calculating the transient temperature rise of each layer structure of the cable within the step size Δt, that is, the temperature of the conductor layer at the current moment, the temperature of multiple insulation layers at the current moment, the temperature of the air gap layer at the current moment, the temperature of the metal sheath at the current moment, and the temperature of the outer sheath at the current moment.

[0059] In the specific implementation, the heat conduction equation of the thermal circuit model is:

[0060]

[0061] Where Q0 is the heat capacity of the conductor layer, and W0 is the Joule heat of the conductor layer;

[0062] n is the number of insulating layers arranged from the inside to the outside, i is a positive integer, 2≤i<n;

[0063] Q 1-1 is the heat capacity of the first insulating layer, Q 1-i is the heat capacity of the i-th insulating layer, Q 1-n is the heat capacity of the nth insulating layer;

[0064] W 1-1 is the dielectric loss of the first insulating layer, W 1-i is the dielectric loss of the i-th insulating layer, W 1-n is the dielectric loss of the nth insulating layer;

[0065] θ 1-1 is the temperature of the first insulating layer, θ 1-2 is the temperature of the second insulating layer, θ 1-i is the temperature of the i-th insulating layer, θ 1-(n-1) is the temperature of the n-1th insulating layer, θ 1-(i-1) is the temperature of the i-1th insulating layer, θ1-n is the temperature of the nth insulating layer;

[0066] T 1-1 is the thermal resistance of the first insulation layer, T 1-(i-1) is the thermal resistance of the i-1th insulation layer, T 1-i is the thermal resistance of the i-th insulation layer, T 1-(n-1) is the thermal resistance of the n-1th insulation layer, T 1-n is the thermal resistance of the nth insulation layer;

[0067] Q2 is the heat capacity of the air gap layer, θ2 is the temperature of the air gap layer, and T2 is the thermal resistance of the air gap layer;

[0068] Q3 is the heat capacity of the metal sheath, θ3 is the temperature of the metal sheath, T3 is the thermal resistance of the metal sheath, and W2 is the loss of the metal sheath;

[0069] Q4 is the heat capacity of the outer sheath, θ4 is the temperature of the outer sheath;

[0070] τ is time.

[0071] Initially, the temperature of the cable surface environment can be measured, and the temperature of each layer of the cable structure can be set to the temperature of the cable surface environment. Subsequently, the temperature of the cable surface environment can be continuously measured, and the temperature of each layer of the thermal circuit model at each moment can be continuously solved through differentiation.

[0072] Step 103 : Calculate the expansion amount of the multiple insulation layers at the current moment based on the temperature of each layer structure of the thermal circuit model at the current moment.

[0073] like Figure 3 As shown in the figure, when the cable is not transmitting electric energy, there is an air gap layer between the insulation layer and the metal sheath before expansion. During the process of the cable transmitting electric energy, the cable heats up, and the insulation layer expands radially as the temperature rises, gradually approaching the metal sheath. During the expansion process of the insulation layer, the thickness of the air gap layer changes significantly, and the thermal resistance of the air gap layer changes significantly, which has a great impact on the heat transfer inside the cable.

[0074] In this embodiment, the radial expansion amount ΔL of the plurality of insulation layers at the current moment may be measured based on the temperature of each layer structure of the thermal circuit model at the current moment.

[0075] In general, the expansion of multiple insulation layers is:

[0076]

[0077] Where, ΔL t is the expansion of multiple insulation layers at the current time t, ΔL t-Δt is the expansion of multiple insulation layers at the last moment t-Δt. At the initial moment, ΔL t-Δt=0, D1 is the outer diameter of the outermost (i.e., nth) insulating layer before expansion, D0 is the outer diameter of the conductor layer, θ(r) is the temperature of each insulating layer, α is the expansion coefficient, r is the radius of the outermost insulating layer, I is the current, R is the resistance, and C1 and C2 are both hyperparameters.

[0078] Then, the expansion amount of multiple insulation layers at the current moment is:

[0079]

[0080] Where, ΔL t1 is the expansion amount of multiple insulation layers at the current time t1, ΔL t0 is the expansion of multiple insulation layers at the last moment t0. At the initial moment, ΔL t0 =0, D1 is the outer diameter of the outermost (i.e., nth) insulating layer before expansion, D0 is the outer diameter of the conductor layer, θ t1 (r) is the temperature of each insulating layer at the current time t1, θ t0 (r) is the temperature of each insulating layer at the previous moment t0, α is the expansion coefficient, and r is the radius of the outermost insulating layer.

[0081] Step 104: Calculate the expansion degree of the multiple insulation layers from the air gap layer to the metal sheath according to the expansion amount to obtain the fit degree.

[0082] Generally, when the insulation layer expands to fill the entire air gap layer, the thermal expansion stops when the insulation layer hits the metal sheath. In this embodiment, the degree to which the insulation layer expands from the air gap layer to the metal sheath (i.e., the expansion degree) can be calculated based on the expansion amount of the insulation layer and recorded as the fit.

[0083] In the specific implementation, the degree of cooperation is:

[0084]

[0085] Among them, C r is the degree of fit, ΔL t is the expansion amount of multiple insulation layers at time t, D1 is the outer diameter of the outermost insulation layer before expansion, and D2 is the outer diameter of the air gap layer.

[0086] In this embodiment, the thermal resistance of the air gap layer in the thermal circuit model of the cable can be corrected in real time using the expansion amount of multiple insulation layers, thereby reflecting the radial thermal expansion process of multiple insulation layers in the thermal circuit model, and reflecting the termination of thermal expansion in the thermal circuit model of the cable based on the degree of fit.

[0087] Step 105 : Calculate the thermal resistance of the air gap layer at the current moment based on the degree of fit and the amount of expansion, and then return to step 102 .

[0088] In this embodiment, the expansion amount of the insulation layer and the thermal resistance of the air gap layer can be updated in an iterative manner (steps 102 to 105) to form a cable optimization thermal evaluation algorithm that takes into account the thermal expansion of the cable. That is, the thermal resistance of the air gap layer at the current moment can be updated in combination with the degree of fit and the expansion amount of multiple insulation layers. An iteration of the thermal resistance of the air gap layer is completed until the number of iterations n reaches the set upper limit Nε of the number of iterations, at which time the iteration is stopped.

[0089] The cable optimization thermal assessment algorithm that takes into account the thermal expansion of the cable can dynamically correct the expansion of the insulation layer and the thermal resistance of the air gap layer, thereby more accurately evaluating the changes in the internal and external temperatures of the cable during thermal expansion and obtaining more accurate cable thermal assessment results.

[0090] In a specific implementation, it can be determined whether the matching degree Cr is greater than or equal to 1.

[0091] If the matching degree is greater than or equal to 1 (i.e., Cr≥1), it means that multiple insulation layers have expanded to the limit, the outer diameter of the outermost insulation layer is the same as the inner diameter of the metal sheath, and the air gap layer disappears. The thermal resistance of the air gap layer at the current moment is set to 0.

[0092] If the degree of fit is less than 1 (i.e., Cr < 1), it indicates that there is an air gap between multiple insulation layers and the metal sheath. The thermal conductivity of air is poor, and the air gap thermal resistance is considered. In this case, the thermal resistance of the air gap at the current moment is calculated using the expansion amount.

[0093] Assuming that at time t, the expansion of multiple insulation layers is ΔLt, then the outer diameter of the outermost insulation layer (i.e., the inner diameter of the air gap layer) increases by 2ΔLt. Then, the thermal resistance of the air gap layer at the current moment is:

[0094]

[0095] Among them, T 2t is the thermal resistance of the air gap layer at time t, λ2 is the thermal conductivity of the air gap layer, D1 is the outer diameter of the outermost insulating layer before expansion, D2 is the outer diameter of the air gap layer, ΔL t is the expansion amount of multiple insulation layers at time t.

[0096] Step 106: When the specified time is reached, the temperature of each layer structure in the heat circuit model is output.

[0097] In practical applications, when the specified time tNε is reached, the temperature of each layer structure in the thermal circuit model calculated from the initial time t0 to the end time tNε can be output, that is, the temperature of the conductor layer at each time, the temperature of multiple insulation layers at each time, the temperature of the air gap layer at each time, the temperature of the metal sheath at each time, and the temperature of the outer sheath at each time, so as to realize timely update of the thermal resistance of the air gap layer, reflect the influence of thermal expansion on the thermal evaluation of the cable in the thermal circuit model, and then form a cable optimization thermal evaluation algorithm taking into account the thermal expansion of the cable.

[0098] In this embodiment, the cable is converted into an equivalent thermal circuit model; the structure of the thermal circuit model includes a conductor layer, multiple insulation layers, an air gap layer, a metal sheath, and an outer sheath; the thermal resistance of the air gap layer at the previous moment is substituted into the heat conduction equation of the thermal model to obtain the temperature of each layer structure of the thermal circuit model at the current moment; the expansion of the multiple insulation layers at the current moment is calculated based on the temperature of each layer structure of the thermal circuit model at the current moment; the expansion degree of the multiple insulation layers from the air gap layer to the metal sheath is calculated based on the expansion amount to obtain the fit; the thermal resistance of the air gap layer at the current moment is calculated based on the fit and expansion amount; and at the specified moment, the temperature of each layer structure in the thermal circuit model is output. This embodiment takes into account the thermal expansion of the insulation layer and the thermal resistance correction of the air gap layer to perform thermal evaluation of the cable, effectively improving the accuracy of the thermal evaluation and providing a data basis for accurately guiding the formulation of load scheduling strategies based on cable temperature, fully tapping the transmission potential of the cable, improving the asset utilization rate of the transmission system, and addressing the challenges brought by the volatility of renewable energy power generation.

[0099] Example 2

[0100] See also Figure 4 , shows a flow chart of a cable temperature detection method considering dynamic parameter characteristics provided by the second embodiment of the present invention. This embodiment adds a step size setting mechanism based on the previous embodiment. Figure 4 As shown, the method includes:

[0101] Step 401: Set multiple candidate values ​​for the step length between two adjacent moments.

[0102] In the cable optimization thermal evaluation algorithm taking into account the thermal expansion of the cable, the update speed of the air gap layer thermal resistance and the update frequency of the cable surface temperature are determined by the step size Δt between two adjacent moments.

[0103] If the step size Δt is too large, the update speed of the thermal resistance of the air gap layer and the cable surface temperature may be too slow, resulting in calculation errors.

[0104] If the step size Δt is too small, the calculation amount of the algorithm may be greatly increased due to the frequent update of the thermal resistance of the air gap layer, resulting in a slower calculation speed.

[0105] In this embodiment, multiple candidate values ​​may be set for the step length between two adjacent moments by using a method such as equal-interval generation, and an optimization operation may be performed on the multiple candidate values ​​to find a suitable candidate value to assign to the step length.

[0106] Step 402: When using each candidate value as a step size, record the temperature of each layer structure in the thermal circuit model to obtain a first sampling temperature.

[0107] In this embodiment, each candidate value can be traversed, and the method of the first embodiment can be called to sequentially use each candidate value as a step size for calculation to obtain the temperature of each layer structure in the thermal circuit model and obtain the first sampling temperature.

[0108] Step 403: When performing a simulation experiment on the cable, the temperature of each layer structure in the cable is recorded to obtain a second sampling temperature.

[0109] In this embodiment, a simulation experiment may be performed on the cable, and the temperature of each layer structure in the cable produced by the experiment may be recorded to obtain a second sampling temperature.

[0110] Generally, the structure of each layer for sampling the cable temperature is the same as that for calculating the temperature using the thermal circuit model, in order to facilitate comparison.

[0111] Step 404: For each candidate value, calculate the error between the first sampling temperature and the second sampling temperature.

[0112] In this embodiment, the temperature of one layer of the structure (eg, the conductor layer) may be selected from the thermal circuit model, and the error between the first sampling temperature and the second sampling temperature may be calculated at the same time.

[0113] Exemplarily, the error between the first sampling temperature and the second sampling temperature is an absolute average error, that is, the error between the first sampling temperature and the second sampling temperature is:

[0114]

[0115] Where ΔT av is the error, n is the number of the first sampling temperature and the number of the second sampling temperature, i∈n, θ ci is the first sampling temperature of the i-th, θ si is the i-th second sampling temperature.

[0116] Step 405: For each candidate value, calculate the time of the first sampling temperature.

[0117] In this embodiment, each candidate value may be traversed, and the time (ie, time consumption) of calculating the first sampling temperature using each candidate value by calling the method of the first embodiment may be counted.

[0118] Step 406 : Take the intersection of the candidate values ​​corresponding to the multiple errors with the lowest values ​​and the candidate values ​​corresponding to the multiple times with the lowest values ​​to obtain a candidate set.

[0119] In this embodiment, a plurality of errors between the first sampling temperature and the second sampling temperature may be arranged to obtain an error variation curve, and a plurality of times for calculating the first sampling temperature may be arranged to obtain a time variation curve.

[0120] On the error variation curve, multiple errors with the lowest values ​​are screened out, and, on the time variation curve, multiple times with the lowest values ​​are screened out.

[0121] The candidate values ​​corresponding to the multiple errors with the lowest values ​​and the candidate values ​​corresponding to the multiple times with the lowest values ​​are intersected to obtain a candidate set.

[0122] Step 407: Filter out a candidate value from the candidate set and assign it to the step length.

[0123] For the candidate values ​​in the candidate set, a candidate value can be screened out by manual confirmation or other methods and assigned to the step length, so that the candidate value with smaller error and calculation time is used as the step length, taking into account the accuracy and efficiency of thermal evaluation of the cable.

[0124] For example, Figure 5 As shown in the figure, the input current I = 1150A generates the yellow time variation curve and the red error variation curve respectively. When the step size is set to 10 minutes, further reducing the step size can no longer effectively reduce the error, and the time will increase significantly as the step size decreases. Therefore, selecting 10 minutes as the step size can take into account both accuracy and efficiency.

[0125] Step 408: Convert the cable into an equivalent thermal circuit model.

[0126] The structure of the thermal circuit model includes a conductor layer, multiple insulation layers, an air gap layer, a metal sheath and an outer sheath.

[0127] Step 409: Substitute the thermal resistance of the air gap layer at the previous moment into the heat conduction equation of the thermal circuit model to obtain the temperature of each layer structure of the thermal circuit model at the current moment.

[0128] Step 410: Calculate the expansion amount of the multiple insulation layers at the current moment based on the temperature of each layer structure of the thermal circuit model at the current moment.

[0129] Step 411: Calculate the expansion degree of the insulation layer from the air gap layer to the metal sheath based on the expansion amount to obtain the degree of fit.

[0130] Step 412 : Calculate the thermal resistance of the air gap layer at the current moment based on the degree of fit and the amount of expansion, and then return to step 409 .

[0131] Step 413: When the specified time is reached, the temperature of each layer structure in the thermal circuit model is output.

[0132] Example 3

[0133] See also Figure 6 , shows a schematic structural diagram of a cable temperature detection device considering dynamic parameter characteristics provided by the third embodiment of the present invention. Figure 6 As shown, the device includes:

[0134] Thermal circuit model conversion module 601 is used to convert the cable into an equivalent thermal circuit model; the structure of the thermal circuit model includes a conductor layer, multiple insulation layers, an air gap layer, a metal sheath and an outer sheath;

[0135] A temperature calculation module 602 is configured to substitute the thermal resistance of the air gap layer at a previous moment into the heat conduction equation of the thermal circuit model to obtain the temperature of each layer structure of the thermal circuit model at a current moment;

[0136] An expansion calculation module 603 is used to calculate the expansion of the plurality of insulating layers at a current moment based on the temperature of each layer structure of the thermal circuit model at a current moment;

[0137] A fit calculation module 604 is configured to calculate the expansion degree of the plurality of insulating layers from the air gap layer to the metal sheath according to the expansion amount to obtain a fit;

[0138] A thermal resistance calculation module 605 is configured to calculate the thermal resistance of the air gap layer at the current moment based on the degree of fit and the expansion amount, and return to execute the temperature calculation module 602;

[0139] The temperature output module 606 is used to output the temperature of each layer structure in the thermal circuit model when a specified time is reached.

[0140] In one embodiment of the present invention, the heat conduction equation is:

[0141]

[0142] Wherein, Q0 is the heat capacity of the conductor layer, and W0 is the Joule heat of the conductor layer;

[0143] n is the number of layers of the insulating layer arranged from the inside to the outside, 2≤i<n;

[0144] Q 1-1 is the heat capacity of the insulating layer 1, Q 1-i is the heat capacity of the insulating layer of the i-th layer, Q 1-n is the heat capacity of the nth insulating layer;

[0145] W 1-1is the dielectric loss of the first layer of insulation, W 1-i is the dielectric loss of the insulating layer of the i-th layer, W 1-n is the dielectric loss of the insulating layer of the nth layer;

[0146] θ 1-1 is the temperature of the insulating layer 1, θ 1-2 is the temperature of the second insulating layer, θ 1-i is the temperature of the insulating layer of the i-th layer, θ 1-(i-1) is the temperature of the insulating layer of the i-1th layer, θ 1-(n-1) is the temperature of the insulating layer of the n-1th layer, θ 1-n is the temperature of the insulating layer of the nth layer;

[0147] T 1-1 is the thermal resistance of the first insulation layer, T 1-(i-1) is the thermal resistance of the insulation layer of the i-1th layer, T 1-i is the thermal resistance of the insulation layer of the i-th layer, T 1-(n-1) is the thermal resistance of the insulation layer (n-1), T 1-n is the thermal resistance of the nth insulating layer;

[0148] Q2 is the heat capacity of the air gap layer, θ2 is the temperature of the air gap layer, and T2 is the thermal resistance of the air gap layer;

[0149] Q3 is the heat capacity of the metal sheath, θ3 is the temperature of the metal sheath, T3 is the thermal resistance of the metal sheath, and W2 is the loss of the metal sheath;

[0150] Q4 is the heat capacity of the outer sheath, θ4 is the temperature of the outer sheath;

[0151] τ is time.

[0152] In one embodiment of the present invention, the expansion amount is:

[0153]

[0154] Where, ΔL t1 is the expansion amount of the plurality of insulating layers at the current time t1, ΔL t0 is the expansion amount of the plurality of insulating layers at the previous moment t0. At the initial moment, ΔL t0 =0, D1 is the outer diameter of the outermost insulating layer before expansion, D0 is the outer diameter of the conductor layer, θ t1 (r) is the temperature of each insulating layer at the current time t1, θ t0 (r) is the temperature of each insulating layer at the previous moment t0, α is the expansion coefficient, and r is the radius of the outermost insulating layer.

[0155] In one embodiment of the present invention, the degree of fit is:

[0156]

[0157] Among them, C r is the degree of fit, ΔL t is the expansion amount of the plurality of insulating layers at time t, D1 is the outer diameter of the outermost insulating layer before expansion, and D2 is the outer diameter of the air gap layer.

[0158] In one embodiment of the present invention, the thermal resistance calculation module 605 includes:

[0159] a first thermal resistance updating module, configured to set the thermal resistance of the air gap layer at a current moment to 0 if the degree of fit is greater than or equal to 1;

[0160] The second thermal resistance updating module is configured to calculate the thermal resistance of the air gap layer at a current moment using the expansion amount if the degree of fit is less than 1.

[0161] In one embodiment of the present invention, the thermal resistance of the air gap layer at the current moment is:

[0162]

[0163] Among them, T 2t is the thermal resistance of the air gap layer at time t, λ2 is the thermal conductivity of the air gap layer, D1 is the outer diameter of the outermost insulating layer before expansion, D2 is the outer diameter of the air gap layer, ΔL t is the expansion amount of the plurality of insulating layers at time t.

[0164] In one embodiment of the present invention, it further comprises:

[0165] A candidate value setting module is used to set multiple candidate values ​​for the step length between two adjacent moments;

[0166] a first sampling temperature recording module, configured to record the temperature of each layer structure in the thermal circuit model when using each candidate value as a step size to obtain a first sampling temperature;

[0167] A second sampling temperature recording module is used to record the temperature of each layer structure in the cable when performing a simulation experiment on the cable to obtain a second sampling temperature;

[0168] an error calculation module, configured to calculate, for each candidate value, an error between the first sampling temperature and the second sampling temperature;

[0169] a time statistics module, configured to calculate, for each candidate value, the time taken to perform the first sampling temperature calculation;

[0170] an intersection module, configured to obtain an intersection between the candidate values ​​corresponding to the multiple errors with the lowest values ​​and the candidate values ​​corresponding to the multiple times with the lowest values, to obtain a candidate set;

[0171] The step length assignment module is used to select a candidate value from the candidate set and assign it to the step length.

[0172] In one embodiment of the present invention, the error is:

[0173]

[0174] Where ΔT av is the error, n is the number of the first sampling temperatures and the number of the second sampling temperatures, i∈n, θ ci is the first sampling temperature of the ith si is the i-th second sampling temperature.

[0175] The cable temperature detection device considering dynamic parameter characteristics provided in an embodiment of the present invention can execute the cable temperature detection method considering dynamic parameter characteristics provided in any embodiment of the present invention, and has the corresponding functional modules and beneficial effects of executing the cable temperature detection method considering dynamic parameter characteristics.

[0176] Example 4

[0177] See also Figure 7 , shows a schematic structural diagram of an electronic device provided by an embodiment of the present invention. The electronic device is intended to represent various forms of digital computers, such as laptop computers, desktop computers, workstations, personal digital assistants, blade servers, mainframe computers, and other suitable computers. The electronic device may also represent various forms of mobile devices, such as personal digital processing, cellular phones, smart phones, wearable devices (such as helmets, glasses, watches, etc.), and other similar computing devices. The components shown herein, their connections and relationships, and their functions are merely examples and are not intended to limit the implementation of the present invention described and / or claimed herein.

[0178] like Figure 7As shown, the electronic device 10 includes at least one processor 11 and a memory, such as a read-only memory (ROM) 12, a random access memory (RAM) 13, etc., which is communicatively connected to the at least one processor 11. The memory stores a computer program that can be executed by the at least one processor. The processor 11 can perform various appropriate actions and processes according to the computer program stored in the read-only memory (ROM) 12 or the computer program loaded from the storage unit 18 into the random access memory (RAM) 13. Various programs and data required for the operation of the electronic device 10 can also be stored in the RAM 13. The processor 11, ROM 12, and RAM 13 are connected to each other via a bus 14. An input / output (I / O) interface 15 is also connected to the bus 14.

[0179] Multiple components in the electronic device 10 are connected to the I / O interface 15, including an input unit 16, such as a keyboard, a mouse, etc.; an output unit 17, such as various types of displays, speakers, etc.; a storage unit 18, such as a magnetic disk, an optical disk, etc.; and a communication unit 19, such as a network card, a modem, a wireless communication transceiver, etc. The communication unit 19 allows the electronic device 10 to exchange information / data with other devices via a computer network such as the Internet and / or various telecommunication networks.

[0180] Processor 11 can be any general-purpose and / or specialized processing component with processing and computing capabilities. Some examples of processor 11 include, but are not limited to, a central processing unit (CPU), a graphics processing unit (GPU), various specialized artificial intelligence (AI) computing chips, various processors running machine learning model algorithms, digital signal processors (DSPs), and any other suitable processor, controller, microcontroller, etc. Processor 11 executes the various methods and processes described above, such as the cable temperature detection method that considers dynamic parameter characteristics.

[0181] In some embodiments, the cable temperature detection method considering dynamic parameter characteristics can be implemented as a computer program, which is tangibly contained in a computer-readable storage medium, such as storage unit 18. In some embodiments, part or all of the computer program can be loaded and / or installed on the electronic device 10 via ROM 12 and / or communication unit 19. When the computer program is loaded into RAM 13 and executed by processor 11, one or more steps of the cable temperature detection method considering dynamic parameter characteristics described above can be performed. Alternatively, in other embodiments, processor 11 can be configured to execute the cable temperature detection method considering dynamic parameter characteristics by any other appropriate means (e.g., by means of firmware).

[0182] Various embodiments of the systems and techniques described herein can be implemented in digital electronic circuit systems, integrated circuit systems, field programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), application specific standard products (ASSPs), system-on-chip systems (SOCs), programmable logic devices (CPLDs), computer hardware, firmware, software, and / or combinations thereof. These various embodiments can include being implemented in one or more computer programs that are executable and / or interpreted on a programmable system that includes at least one programmable processor, which can be a special purpose or general purpose programmable processor that can receive data and instructions from a storage system, at least one input device, and at least one output device, and transmit data and instructions to the storage system, the at least one input device, and the at least one output device.

[0183] Computer programs for implementing the methods of the present invention may be written in any combination of one or more programming languages. These computer programs may be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing device, such that when the computer program is executed by the processor, the functions / operations specified in the flowcharts and / or block diagrams are implemented. The computer program may be executed entirely on the machine, partially on the machine, as a stand-alone software package, partially on the machine and partially on a remote machine, or entirely on a remote machine or server.

[0184] In the context of the present invention, computer-readable storage media can be tangible media that can contain or store a computer program for use with an instruction execution system, device or equipment or used in combination with an instruction execution system, device or equipment. Computer-readable storage media can include but are not limited to electronic, magnetic, optical, electromagnetic, infrared or semiconductor systems, devices or equipment, or any suitable combination of the foregoing. Alternatively, computer-readable storage media can be machine-readable signal media. More specific examples of machine-readable storage media can include electrical connections based on one or more lines, portable computer disks, hard disks, random access memories (RAM), read-only memories (ROM), erasable programmable read-only memories (EPROM or flash memory), optical fibers, portable compact disk read-only memories (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination of the foregoing.

[0185] To provide interaction with a user, the systems and techniques described herein can be implemented on an electronic device having: a display device (e.g., a CRT (cathode ray tube) or LCD (liquid crystal display) monitor) for displaying information to the user; and a keyboard and pointing device (e.g., a mouse or trackball) through which the user can provide input to the electronic device. Other types of devices can also be used to provide interaction with the user; for example, the feedback provided to the user can be any form of sensory feedback (e.g., visual feedback, auditory feedback, or tactile feedback); and input from the user can be received in any form (including acoustic input, voice input, or tactile input).

[0186] The systems and techniques described herein can be implemented in a computing system that includes back-end components (e.g., as a data server), or a computing system that includes middleware components (e.g., an application server), or a computing system that includes front-end components (e.g., a user computer with a graphical user interface or web browser through which a user can interact with implementations of the systems and techniques described herein), or a computing system that includes any combination of such back-end components, middleware components, or front-end components. The components of the system can be interconnected by any form or medium of digital data communication (e.g., a communication network). Examples of communication networks include: a local area network (LAN), a wide area network (WAN), a blockchain network, and the Internet.

[0187] A computing system may include clients and servers. The clients and servers are typically remote from each other and typically interact via a communication network. This client-server relationship arises through computer programs running on the respective computers, creating a client-server relationship. The server may be a cloud server, also known as a cloud computing server or cloud host. This server is a hosting product within the cloud computing service ecosystem that addresses the management difficulties and limited scalability of traditional physical hosting and VPS services.

[0188] Example 5

[0189] An embodiment of the present invention further provides a computer program product, which includes a computer program. When the computer program is executed by a processor, the method for detecting cable temperature considering dynamic parameter characteristics as provided in any embodiment of the present invention is implemented.

[0190] The computer program product may be implemented by writing computer program code for performing the operations of the present invention in one or more programming languages, or a combination thereof, including object-oriented programming languages ​​such as Java, Smalltalk, C++, and conventional procedural programming languages ​​such as "C" or similar programming languages. The program code may be executed entirely on the user's computer, partially on the user's computer, as a stand-alone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving a remote computer, the remote computer may be connected to the user's computer via any type of network, including a local area network (LAN) or a wide area network (WAN), or may be connected to an external computer (e.g., via the Internet using an Internet service provider).

[0191] It should be understood that the various forms of the processes shown above can be used to reorder, add, or delete steps. For example, the steps described in the present invention can be performed in parallel, sequentially, or in a different order, as long as the desired results of the technical solution of the present invention can be achieved. This is not limited herein.

[0192] The above specific embodiments do not limit the scope of protection of the present invention. Those skilled in the art will appreciate that various modifications, combinations, sub-combinations, and substitutions may be made based on design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention are intended to be included within the scope of protection of the present invention.

Claims

1. A cable temperature detection method considering dynamic parameter characteristics, characterized in that: include: Converting the cable into an equivalent thermal circuit model; the structure of the thermal circuit model includes a conductor layer, multiple insulation layers, an air gap layer, a metal sheath and an outer sheath; Substituting the thermal resistance of the air gap layer at the previous moment into the heat conduction equation of the thermal model to obtain the temperature of each layer structure of the thermal circuit model at the current moment; Calculating the expansion amount of the plurality of insulating layers at the current moment according to the temperature of each layer structure of the thermal circuit model at the current moment; Calculating the expansion degree of the plurality of insulating layers from the air gap layer to the metal sheath according to the expansion amount to obtain a fit degree; Calculating the thermal resistance of the air gap layer at a current moment based on the degree of fit and the amount of expansion, returning to the step of substituting the thermal resistance of the air gap layer at a previous moment into the heat conduction equation of the thermal circuit model to obtain the temperature of each layer structure of the thermal circuit model at the current moment; When the specified time is reached, the temperature of each layer structure in the thermal circuit model is output.

2. The method according to claim 1, characterized in that The heat conduction equation is: Wherein, Q0 is the heat capacity of the conductor layer, and W0 is the Joule heat of the conductor layer; n is the number of layers of the insulating layer arranged from the inside to the outside, 2≤i<n; Q 1-1 is the heat capacity of the insulating layer 1, Q 1-i is the heat capacity of the insulating layer of the i-th layer, Q 1-n is the heat capacity of the nth insulating layer; W 1-1 is the dielectric loss of the first layer of insulation, W 1-i is the dielectric loss of the insulating layer of the i-th layer, W 1-n is the dielectric loss of the insulating layer of the nth layer; θ 1-1 is the temperature of the insulating layer 1, θ 1-2 is the temperature of the second insulating layer, θ 1-i is the temperature of the insulating layer of the i-th layer, θ 1-(i-1) is the temperature of the insulating layer of the i-1th layer, θ 1-(n-1) is the temperature of the insulating layer of the n-1th layer, θ 1-n is the temperature of the insulating layer of the nth layer; T 1-1 is the thermal resistance of the first insulation layer, T 1-(i-1) is the thermal resistance of the insulation layer of the i-1th layer, T 1-i is the thermal resistance of the insulation layer of the i-th layer, T 1-(n-1) is the thermal resistance of the insulation layer (n-1), T 1-n is the thermal resistance of the nth insulating layer; Q2 is the heat capacity of the air gap layer, θ2 is the temperature of the air gap layer, and T2 is the thermal resistance of the air gap layer; Q3 is the heat capacity of the metal sheath, θ3 is the temperature of the metal sheath, T3 is the thermal resistance of the metal sheath, and W2 is the loss of the metal sheath; Q4 is the heat capacity of the outer sheath, θ4 is the temperature of the outer sheath; τ is time.

3. The method according to claim 1, characterized in that The expansion amount is: Where, ΔL t1 is the expansion amount of the plurality of insulating layers at the current time t1, ΔL t0 is the expansion amount of the plurality of insulating layers at the previous moment t0. At the initial moment, ΔL t0 =0, D1 is the outer diameter of the outermost insulating layer before expansion, D0 is the outer diameter of the conductor layer, θ t1 (r) is the temperature of each insulating layer at the current time t1, θ t0 (r) is the temperature of each insulating layer at the previous moment t0, α is the expansion coefficient, and r is the radius of the outermost insulating layer.

4. The method according to claim 1, wherein The degree of fit is: Among them, C r is the degree of fit, ΔL t is the expansion amount of the plurality of insulating layers at time t, D1 is the outer diameter of the outermost insulating layer before expansion, and D2 is the outer diameter of the air gap layer.

5. The method according to claim 4, characterized in that The calculating the thermal resistance of the air gap layer at the current moment based on the degree of fit and the expansion amount includes: If the degree of fit is greater than or equal to 1, the thermal resistance of the air gap layer at the current moment is set to 0; If the degree of fit is less than 1, the thermal resistance of the air gap layer at the current moment is calculated using the expansion amount.

6. The method according to claim 5, characterized in that The thermal resistance of the air gap layer at the current moment is: Among them, T 2t is the thermal resistance of the air gap layer at time t, λ2 is the thermal conductivity of the air gap layer, D1 is the outer diameter of the outermost insulating layer before expansion, D2 is the outer diameter of the air gap layer, ΔL t is the expansion amount of the plurality of insulating layers at time t.

7. The method according to any one of claims 1 to 6, characterized in that Also includes: Setting multiple candidate values ​​for the step length between two adjacent moments; When using each candidate value as the step size, recording the temperature of each layer structure in the thermal circuit model to obtain a first sampling temperature; When performing a simulation experiment on the cable, the temperature of each layer structure in the cable is recorded to obtain a second sampling temperature; For each candidate value, calculating an error between the first sampling temperature and the second sampling temperature; For each candidate value, statistically calculating the time of the first sampling temperature; Obtain an intersection between the candidate values ​​corresponding to the multiple errors with the lowest values ​​and the candidate values ​​corresponding to the multiple times with the lowest values, to obtain a candidate set; A candidate value is selected from the candidate set and assigned to the step size.

8. The method according to claim 7, characterized in that The error is: Where, ΔT av is the error, n is the number of the first sampling temperatures and the number of the second sampling temperatures, i∈n, θ ci is the first sampling temperature of the ith si is the second sampling temperature of the i-th one.

9. An electronic device, characterized in that: The electronic device comprises: at least one processor; and a memory communicatively connected to the at least one processor; wherein, The memory stores a computer program executable by the at least one processor. The computer program is executed by the at least one processor to enable the at least one processor to perform the cable temperature detection method considering dynamic parameter characteristics according to any one of claims 1 to 8.

10. A computer-readable storage medium, characterized in that The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the cable temperature detection method considering dynamic parameter characteristics according to any one of claims 1 to 8 is implemented.

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