Methods, equipment, and media for simulating and calculating the surface temperature and conductor temperature of cables.

Abstract

This invention discloses a method, equipment, and medium for simulating and calculating the surface temperature and conductor temperature of cables. The invention constructs a first temperature calculation model for cables operating under DC conditions and a second temperature calculation model for cables operating under AC conditions. Depending on the cable's operating condition, the surface temperature and conductor temperature of the cable are calculated in real time using either the first or second temperature calculation model. The calculated values ​​are then compared and verified using actual measured values ​​of the cable's surface and conductor temperatures. This invention constructs temperature calculation models corresponding to different operating conditions for cables, enabling dynamic simulation calculation of the internal conductor and surface temperatures of cables during load operation and power changes. The calculated values ​​are then compared and verified using actual measured values ​​of the surface and conductor temperatures, thereby achieving accurate temperature calculation and condition assessment for oil-filled cables.

Description

Technical Field

[0001] This invention relates to the field of cable condition assessment technology, specifically to a dynamic simulation calculation method for the surface temperature and internal conductor temperature of an oil-filled cable during load operation and power variation, applicable to the safety operation assessment and condition monitoring of oil-filled cables. Background Technology

[0002] Submarine cables, also known as submarine cables, are crucial for the development of marine energy projects such as cross-sea power transmission and offshore wind power. Oil-filled submarine cables (also called oil-filled electrical cables) serve as the core power transmission carrier, and the operating temperature of their internal conductors directly affects the cable's insulation performance and service life. When the cable is under load, the heat generated by conductor loss and dielectric loss is closely related to the external marine environment (seawater temperature, ocean currents, geological conditions) and its own structure (thermal resistance and thermal capacity of each layer). Excessive cable temperature can lead to insulation aging, sealing failure, and other malfunctions. Therefore, accurately assessing the internal and external temperature changes of oil-filled submarine cables using simulation calculations is of great significance for evaluating the operating status of oil-filled cables, preventing faults, and ensuring power grid safety. This is crucial for preventing cable temperature from exceeding rated values, which could lead to performance degradation, shortened lifespan, or even accidents.

[0003] The existing technology has the following shortcomings: (1) Lack of calculation methods and dynamic calculation models: There is currently a lack of real-time transient temperature simulation calculation schemes for power changes (such as no-load closing, load fluctuation and adjustment, on-site pressurization and current boosting tests, etc.). (2) Disconnection between monitoring and evaluation: The existing temperature evaluation scheme can only measure the surface temperature of the cable and cannot measure the temperature of the core conductor inside the cable in real time; at the same time, the test scheme lacks theoretical guidance and is not combined with the calculation model, making it difficult to achieve accurate evaluation and early warning of the internal conductor temperature.

[0004] Therefore, this application provides a method for accurately calculating the dynamic temperature changes of oil-filled cables during AC / DC operation, providing theoretical support for the safe operation of oil-filled cables. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a method, device, and medium for simulating and calculating the surface temperature and conductor temperature of cables. This invention aims to solve the problem that existing technologies cannot achieve real-time calculation of the dynamic temperature change of oil-filled cables under load. By constructing calculation models for the conductor temperature and surface temperature of oil-filled cables for different operating conditions and comparing and verifying them with actual temperature measurements, this invention achieves accurate calculation and condition assessment of the temperature of oil-filled cables.

[0006] To solve the above-mentioned technical problems, the present invention provides the following first aspect of the technical solution: a method for simulating and calculating the surface temperature and conductor temperature of a cable, comprising the following steps:

[0007] S1. Construct a first temperature calculation model for the cable under DC operating conditions, and construct a second temperature calculation model for the cable under AC operating conditions;

[0008] S2. Based on the operating conditions of the cable, calculate the surface temperature and conductor temperature of the cable in real time using the first temperature calculation model, or calculate the surface temperature and conductor temperature of the cable in real time using the second temperature calculation model.

[0009] S3. Compare and verify the calculated values ​​from step S2.

[0010] Preferably, in step S1, a first temperature calculation model is constructed based on the conductor loss and insulation leakage loss of the cable.

[0011] Preferably, the first temperature calculation model includes a first calculation formula for calculating the conductor temperature of the cable, as shown in equation (1) below:

[0012]

[0013] In the above formula (1), The conductor temperature of the cable. For ambient temperature, For cable current carrying capacity, The conductor resistance at 20℃ For conductor temperature coefficient, The thermal resistance between the conductor and the sheath. The thermal resistance of the sheath, armor, and the filling material between them. For the thermal resistance of the outer sheath, The thermal resistance of the environment surrounding the cable. The voltage carried by the cable. The insulation resistance per unit length of the cable.

[0014] Preferably, the first temperature calculation model further includes a second calculation formula for calculating the surface temperature of the cable, as shown in equation (2) below:

[0015]

[0016] In the above formula (2), This refers to the surface temperature of the cable.

[0017] Preferably, in step S1, a second temperature calculation model is constructed based on the conductor loss, dielectric loss, and induced loss of the cable.

[0018] Preferably, the second temperature calculation model includes a third calculation formula for calculating the conductor temperature of the cable, as shown in equation (3) below:

[0019]

[0020] In the above formula (3), The conductor temperature of the cable. For ambient temperature, R is the current carrying capacity of the cable, and R is the AC resistance per unit length of conductor at the maximum current carrying capacity. The thermal resistance between the conductor and the sheath. The thermal resistance of the sheath, armor, and the filling material between them. For the thermal resistance of the outer sheath, The thermal resistance of the environment surrounding the cable. Where n is the dielectric loss and n is the number of current-carrying conductors, This represents the ratio of the metal shielding layer loss to the conductor loss. This represents the ratio of armor layer loss to conductor loss.

[0021] Preferably, the second temperature calculation model further includes a fourth calculation formula for calculating the surface temperature of the cable, as shown in equation (4) below:

[0022]

[0023] In the above formula (4), This refers to the surface temperature of the cable.

[0024] Preferably, step S3 involves comparing and verifying the calculated value of step S2 using the actual measured values ​​of the cable's surface temperature and conductor temperature; the actual measured value of the cable's surface temperature comes from the thermocouples installed on the cable's surface, and the actual measured value of the cable's conductor temperature comes from the thermocouples installed on the cable's conductor.

[0025] To solve the above-mentioned technical problems, the present invention provides the following second aspect of the technical solution: a device, which is an electronic device, including a memory and a processor coupled to each other, wherein the processor is used to execute program instructions stored in the memory to realize the above-mentioned method for simulating and calculating the surface temperature and conductor temperature of the cable.

[0026] To solve the above-mentioned technical problems, the present invention provides the following third aspect of the technical solution: a medium, which is a computer-readable storage medium, on which program instructions are stored, and when the program instructions are executed by a processor, the above-mentioned method for simulating and calculating the surface temperature and conductor temperature of the cable is implemented.

[0027] Compared with existing technologies, this invention provides a method, device, and medium for simulating and calculating the surface temperature and conductor temperature of cables, offering the following advantages: First, this invention constructs a first temperature calculation model for the cable under DC operating conditions, and a second temperature calculation model for the cable under AC operating conditions. Further, depending on the cable's operating condition, the surface temperature and conductor temperature of the cable are calculated in real time using either the first or second temperature calculation model. Finally, the calculated values ​​are compared and verified using actual measured values ​​of the cable's surface and conductor temperatures. Through this method, this invention constructs conductor and surface temperature calculation models for oil-filled cables under different operating conditions, enabling dynamic simulation calculation of the internal conductor and surface temperatures of oil-filled cables during load operation and power changes. The calculated values ​​are then compared and verified using actual measured values ​​of the surface and conductor temperatures, thereby achieving accurate temperature calculation and condition assessment of oil-filled cables. Attached Figure Description

[0028] Figure 1 This is a flowchart illustrating the steps of the method for simulating and calculating the surface temperature and conductor temperature of the cable according to the present invention.

[0029] Figure 2 This is a schematic diagram of the thermocouple testing cable temperature device of the present invention;

[0030] Figure 3 This is a comparison chart of DC current boost test temperatures for the present invention;

[0031] Figure 4 This is a temperature comparison chart of the AC current rise test of the present invention;

[0032] Figure 5 This is a schematic diagram of the electronic device of the present invention;

[0033] Figure 6 This is a schematic diagram of the framework of the computer-readable storage medium of the present invention. Detailed Implementation

[0034] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] This invention provides a method for simulating and calculating the surface temperature and conductor temperature of a cable, comprising the following steps S1-S3:

[0036] S1. Construct a first temperature calculation model for the cable under DC operating conditions, and construct a second temperature calculation model for the cable under AC operating conditions. The cable is an oil-filled cable, which is an oil-filled submarine cable. The cable has a core conductor (referred to as the conductor) inside.

[0037] S2. Based on the operating conditions of the cable, calculate the surface temperature and conductor temperature of the cable in real time using either the first temperature calculation model or the second temperature calculation model. It can be understood that when the cable is in DC operating conditions, the first temperature calculation model is used to calculate the surface temperature and conductor temperature in real time, while when the cable is in AC operating conditions, the second temperature calculation model is used to calculate the surface temperature and conductor temperature in real time.

[0038] S3. Compare and verify the calculated values ​​of step S2 using the actual measured values ​​of the cable's surface temperature and conductor temperature.

[0039] The following describes the construction of a temperature calculation model for cables under DC operating conditions: Under DC operating conditions, cables have no induced losses; heat generated by conductor losses is transferred to the environment through the thermal resistance of each layer. Given the characteristic of no induced losses in DC operation, dielectric losses can be ignored when the cable is carrying DC current; preferably, only conductor losses and insulation leakage losses need to be considered. Therefore, preferably, in step S1 above, the first temperature calculation model is constructed based on the cable's conductor losses and insulation leakage losses. The Joule heat power generated by the conductor... This heat is transferred through the conductor-sheath (thermal resistance is as follows) ), Sheath-armor (thermal resistance as follows) ), outer sheath (thermal resistance as follows) ), surrounding environment (thermal resistance is as follows) ) transfer; according to thermal equilibrium, the temperature difference is proportional to the heat power and the total thermal resistance, so the following equation (5) can be obtained:

[0040]

[0041] In the above formula (5), Corresponding conductor loss (W). Corresponding insulation leakage loss (W). The DC resistance per unit length of conductor at maximum current carrying capacity (Ω / km). The conductor temperature of the cable. For the ambient temperature, the meanings of the other parameters in equation (5) above are detailed in the parameter meanings corresponding to equation (1) below, and will not be repeated here.

[0042] Due to the above Changes with temperature and satisfies ( Here, α is the conductor resistance at 20℃, and α is the conductor temperature coefficient (both are standard parameters). Additionally, the above... ( The voltage carried by the cable. (where the insulation resistance is per unit length of the cable), therefore, the formula for calculating the conductor temperature of a cable under DC conditions can be written as follows (1).

[0043] Specifically, the first temperature calculation model includes a first calculation formula for calculating the conductor temperature of the cable, which is shown in equation (1) below:

[0044]

[0045] In the above formula (1), The conductor temperature (°C) of the cable is the transient conductor temperature. The ambient temperature is (°C). The current carrying capacity of the cable is (A). The conductor resistance at 20℃ The temperature coefficient of a conductor; The thermal resistance between the conductor and the sheath (°C / W), i.e. The thermal resistance of the insulation layer is calculated from the thickness of the insulation material and its thermal conductivity. , For thickness, For thermal conductivity, the aforementioned sheath can specifically be a metal sheath such as a lead sheath; Thermal resistance (°C / W) of the sheath, armor, and the filler material between them. The thermal resistance of the outer sheath (°C / W). The thermal resistance (°C / W) of the environment surrounding the cable. The voltage carried by the cable. The insulation resistance per unit length of the cable.

[0046] In the above formula (1), The calculation formula can be written as the following formula (6):

[0047]

[0048] In the above formula (6), The volume resistivity of the insulation is (Ω·m). Δd is the conductor diameter of the cable (m), and Δd is the insulation thickness of the cable (m).

[0049] In addition, the first temperature calculation model mentioned above also includes a second calculation formula for calculating the surface temperature of the cable, which is shown in equation (2) below:

[0050]

[0051] In the above formula (2), The surface temperature of the cable. The conductor temperature of the cable is calculated by the above formula (1). The meanings of the other parameters in the above formula (2) are as follows: see the meanings of the parameters corresponding to the above formula (1), which will not be repeated here.

[0052] The following describes the construction of a temperature calculation model for cables operating under AC conditions: This invention considers the proximity effect and skin effect of conductors under AC conditions, and the induced losses from the cable's metal sheath and armor, as well as the need to consider dielectric losses (i.e., insulation dielectric losses). Therefore, under AC conditions, it is preferable to calculate multiple losses, including coupling conductor loss, dielectric loss, and induced loss. Therefore, preferably, in step S1 above, the second temperature calculation model is constructed based on the cable's conductor loss, dielectric loss, and induced loss.

[0053] The formula for calculating the AC resistance per unit length of conductor (hereinafter referred to as AC resistance of conductor) R under the maximum current carrying capacity is shown in the following formula (7):

[0054]

[0055] In the above formula (7), This refers to the DC resistance per unit length of conductor under the aforementioned maximum current carrying capacity. Add a loss factor to the AC signal. Related to conductor structure and frequency, This information can be obtained from standards or through testing. This invention takes into account conductor losses caused by alternating current. With dielectric loss In addition, the aforementioned inductive losses in each layer include: lead sheath losses. , reinforcement layer loss Copper strip loss Armor damage When calculating induced losses, considering that the magnitude of the induced current is directly proportional to the conductor current and is affected by the cable's geometry, if the internal structure of the cable remains unchanged and the distance between cables is constant, then the ratio of the induced current to the conductor current is constant. Furthermore, the resistance of the induced loss is related to the temperature at that location, and its variation is similar to that of the conductor resistance. Therefore, the ratio of the magnitude of the induced loss to the conductor loss is considered essentially constant, denoted as […]. (The ratio of metal shielding loss to conductor loss) and The ratio of armor layer loss to conductor loss is considered a constant. Among these, the lead sheath loss... , reinforcement layer loss This is collectively referred to as the metal shielding layer loss, and its ratio to the conductor loss is... The calculation formula is shown in equation (8) below:

[0056]

[0057] In the above equation (8), This represents the ratio of the metal shielding layer loss to the conductor loss. For lead sheath loss (W). For reinforcement layer loss (W). For conductor loss (W).

[0058] The aforementioned copper strip loss Armor damage The combined armor layer loss is the ratio of its value to the conductor loss. The calculation formula is shown in equation (9) below:

[0059]

[0060] In the above equation (9), This represents the ratio of armor layer loss to conductor loss. The copper strip loss is (W). Armor loss (W). The conductor loss is W. Therefore, by combining the above loss values, a composite calculation of the internal conductor temperature of an oil-filled cable under AC operating conditions can be performed. Specifically, the second temperature calculation model includes a third calculation formula for calculating the conductor temperature of the cable, as shown in equation (3) below:

[0061]

[0062] In the above formula (3), The conductor temperature of the cable. For ambient temperature, R is the current carrying capacity of the cable, and R is the AC resistance per unit length of conductor at the maximum current carrying capacity (Ω / km). The thermal resistance between the conductor and the sheath. The thermal resistance of the sheath, armor, and the filling material between them. For the thermal resistance of the outer sheath, The thermal resistance of the environment surrounding the cable. Where n is the dielectric loss and n is the number of current-carrying conductors, This represents the ratio of the metal shielding layer loss to the conductor loss. This represents the ratio of armor layer loss to conductor loss.

[0063] In addition, conductor loss It varies with the current and the temperature of the conductor, and its calculation formula can be written as: , R is the operating current, i.e., the current carrying capacity of the cable mentioned above, and R is the AC resistance at the operating temperature, i.e., the AC resistance per unit length of conductor under the maximum current carrying capacity mentioned above. R can also be calculated using the following formula (10):

[0064]

[0065] In the above formula (10), The skin effect is a factor affecting cable conductors; The DC resistance at the conductor's operating temperature; For a single-core cable, the proximity effect is considered as a factor. It is 0. You can follow the above. The calculation is performed using the formula. Skin effect factor of cable conductors. Then calculate according to the following formula (11):

[0066]

[0067] In the above equation (11), The frequency is AC (Hz, the power frequency is usually taken as 50Hz). The magnetic permeability of a conductor material (H / m, 4π×10⁻⁶ for non-magnetic materials such as copper and aluminum) is expressed as... -7 H / m), ρ represents the resistivity of the conductor material (Ω·m, taken as 1.724×10 at 20℃ for copper). -8 Ω·m).

[0068] In single-core cables, the above-mentioned insulation dielectric loss Calculate using the following formula (12):

[0069]

[0070] In the above formula (12), C represents the cable insulation capacitance (determined by the internal materials and structure of the cable). Indicates the cable voltage to ground. This represents the dielectric constant of the cable insulation.

[0071] In addition, under AC operating conditions, when calculating the surface temperature of the cable, the temperature change caused by the thermal resistance of other materials and structures (excluding environmental thermal resistance) should be subtracted from the conductor temperature calculation (only the temperature change caused by the structural thermal resistance of other materials should be retained). , remove , and The second temperature calculation model mentioned above also includes a fourth calculation formula for calculating the surface temperature of the cable, which is shown in equation (4) below:

[0072]

[0073] In the above formula (4), The surface temperature of the cable is given. The meanings of the other parameters in equation (4) are detailed in equation (3), and will not be repeated here.

[0074] Furthermore, in step S3 above, the actual measured value of the cable surface temperature comes from thermocouples installed on the cable surface, and the actual measured value of the cable conductor temperature comes from thermocouples installed on the cable conductor. During actual testing and verification, several thermocouple temperature measurement points are simultaneously arranged on the cable conductor and surface. The actual temperature of various parts of the cable is collected during the cable's operation under load, and further compared with the theoretical calculation value from the aforementioned temperature calculation model formula to verify the accuracy of the calculation method of this invention. Specifically, the data signals collected by the thermocouples can be uploaded to the front end of the detection station, converted into real-time data, and uploaded to the monitoring system for reading and calculation. Additionally, it is preferable to install pressure sensors and power sensors at the terminal station of the oil-filled cable to collect data such as cable pressure and power during energized operation in real time.

[0075] Specifically, the theoretical value can be calculated by substituting various parameters into the aforementioned temperature calculation formula based on data such as the power transmitted by the monitoring system. In the actual verification process, a cable is connected to a current-boosting device 31 and a current transformer (CT) 32 at both ends. The cable is divided into several equal sections, each containing a surface-sensing thermocouple 33 and a conductor-sensing thermocouple. When current is applied to the cable, the rated current causes the cable temperature to rise. The temperature is monitored and detected in real time using thermocouples. A schematic diagram of the thermocouple temperature testing device is shown below. Figure 2 As shown. It can be understood that step S3 above involves using a temperature calculation method to calculate the theoretical temperature and comparing it with the temperature measured by the thermocouple to verify the accuracy of the calculation method.

[0076] The following example uses the temperature calculation of a 500kV oil-filled single-core cable under load to illustrate the calculation of the surface temperature and conductor temperature of the cable under different operating conditions.

[0077] Parameter acquisition: (1) Thermal resistance: (Conductor - Lead Sheath) = 0.679 K·m / W (Insulation thermal resistance, calculated from insulation material thickness and thermal conductivity). , For thickness, (thermal conductivity); [Lead sheath - armor = 0.044 K·m / W (thermal resistance of sheath, armor and filling material in between)]; [Outer sheath = 0.057 K·m / W (thermal resistance of outer sheath material)]; (Thermal resistance of the environment surrounding the cable), calculated based on actual environmental conditions, when the environment is soil, Take 0.71; when the environment is shallow seawater, Take 0.672; when the environment is deep seawater, Take 0.537; when the environment is air, Take 0.245. (2) Conductor resistance: The conductor of this cable can be regarded as pure copper material, therefore, according to the conductor resistance of copper: Temperature coefficient α = 0.00393. (3) Loss-related parameters: AC additional loss coefficient (Determined by conductor stranding structure and frequency 50Hz); the ratio of metal shielding loss to conductor loss. The ratio of armor layer loss to conductor loss (The inductive loss ratio is calculated using finite element simulation of the electromagnetic field, with input cable structure and current frequency); the insulation capacitance C of the cable is determined by the structure and materials of the submarine cable, and is set at 0.239. The dielectric loss of this cable... The calculated value is 16.59 W / m.

[0078] DC operating conditions (taking a rated DC current of 1090A as an example): When the current is 1090A, the environment is deep seawater, and the ambient temperature is 20℃, the line voltage is extremely small and can be ignored; at this time, the conductor temperature of the cable... The calculation is as follows:

[0079]

[0080] The surface temperature of the cable The calculation is as follows:

[0081]

[0082]

[0083] When the current is 1090A DC, the environment is deep seawater, and the ambient temperature is 20℃, the conductor temperature is calculated. Cable surface temperature .

[0084] AC operating conditions (taking a rated AC current of 815A as an example): Under rated operating conditions, when the environment is deep seawater and the ambient temperature is approximately 20℃, the AC rated resistivity (R) of the submarine cable used in this calculation and verification is 0.00002857Ω / m, and the number of current-carrying conductors in a single-core submarine cable is n=1. The conductor temperature of the cable... The calculation is as follows:

[0085]

[0086] The surface temperature of the cable The calculation is as follows:

[0087]

[0088] When the current is 815A AC, the environment is deep seawater, and the ambient temperature is 20℃, the conductor temperature is calculated. Cable surface temperature .

[0089] Data Comparison and Verification: The accuracy of the calculation method of this invention was verified by conducting current-carrying tests on a 500kV oil-filled submarine cable. The test currents were 700A, 761A, 982A, and 1090A for DC, and 407.5A, 543A, 680A, and 815A for AC. The conductor and surface temperatures of the oil-filled submarine cable were measured on-site using thermocouples and compared with the theoretical temperatures calculated using the calculation method. The results are as follows: Figure 3 , Figure 4 As shown, Figure 3 The chart shows a comparison of the DC current-up test temperatures of the corresponding cables under DC operating conditions. When the test current is 700A DC, the measured conductor temperature is approximately 33°C, while the calculated conductor temperature obtained using the calculation method of this invention is approximately 35°C. That is, the error between the calculated conductor temperature and the actual measured temperature is approximately 2°C. In addition, the measured surface temperature is approximately 25°C, while the calculated surface temperature is approximately 26.2°C. That is, the error between the calculated surface temperature and the actual measured surface temperature is approximately 1.2°C. Figure 4 The chart compares the DC current-up test temperatures of the corresponding cables under AC operating conditions. When the test current is 407.5A AC: the measured conductor temperature is approximately 41.3℃, while the calculated conductor temperature is approximately 44℃, meaning the error between the calculated and measured conductor temperatures is approximately 2.7℃. Additionally, the measured surface temperature is approximately 30℃, while the calculated surface temperature is approximately 32.5℃, meaning the error between the calculated and measured surface temperature is approximately 2.5℃. From... Figure 3 , Figure 4 The results show that the calculation method of the present invention has a small error compared with the actual test values ​​of the cable conductor and surface temperature, and the calculation method of the present invention has high accuracy.

[0090] like Figure 5As shown, the present invention also provides an electronic device 1, which includes a memory 11 and a processor 12 coupled to each other. The processor 12 is used to execute program instructions stored in the memory 11 to implement the above-described method for simulating and calculating the surface temperature and conductor temperature of any of the cables. In a specific implementation scenario, the above-described electronic device 1 may include, but is not limited to, a microcomputer or a server. In addition, the electronic device 1 may also include mobile devices such as laptops and tablets, which are not limited here.

[0091] Specifically, the processor 12 controls itself and the memory 11 to implement the simulation calculation method for the surface temperature and conductor temperature of any of the oil-filled cables. The processor 12 can also be called a CPU (Central Processing Unit). The processor 12 may be an integrated circuit chip with signal processing capabilities. The processor 12 can also be a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components. The general-purpose processor can be a microprocessor or any conventional processor. Furthermore, the processor 12 can be implemented using integrated circuit chips.

[0092] In addition, such as Figure 6 As shown, the present invention also provides a medium, which is a computer-readable storage medium 2, on which program instructions 21 are stored. When the program instructions 21 are executed by a processor, they implement the simulation calculation method for the surface temperature and conductor temperature of any of the above-mentioned cables. The storage medium 2 may include various media capable of storing program instructions, such as a USB flash drive, a portable hard drive, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk.

[0093] Compared with existing technologies, this invention provides a method, device, and medium for simulating and calculating the surface temperature and conductor temperature of cables, offering the following advantages: First, this invention constructs a first temperature calculation model for the cable under DC operating conditions, and a second temperature calculation model for the cable under AC operating conditions. Further, depending on the cable's operating condition, the surface temperature and conductor temperature of the cable are calculated in real-time using either the first or second temperature calculation model. Finally, the calculated values ​​are compared and verified using actual measured values ​​of the cable's surface temperature and conductor temperature. This invention differentiates between AC and DC operating conditions, analyzes the temperature calculation method of the internal structure of oil-filled submarine cables layer by layer, constructs a model coupling temperature calculation formulas for multiple layers of cable materials, and performs real-time calculations based on real-time monitoring data. This solves the problem that existing technologies cannot achieve real-time calculation of the dynamic temperature changes of oil-filled submarine cables under load, enabling accurate calculation and evaluation of the temperature of oil-filled submarine cables.

[0094] It should be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0095] Although embodiments of the invention have been shown, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method of simulating surface temperature and conductor temperature of a cable, characterized by, The method comprises the following steps: S1, constructing a first temperature calculation model of the cable under a direct current working condition, and constructing a second temperature calculation model of the cable under an alternating current working condition; S2, calculating the surface temperature and the conductor temperature of the cable in real time by using the first temperature calculation model or the second temperature calculation model according to the working condition of the cable; S3, comparing and verifying the calculation value of the step S2; In the step S1, the first temperature calculation model is constructed according to the conductor loss and the insulation leakage loss of the cable; The first temperature calculation model comprises a first calculation formula for calculating the conductor temperature of the cable, and the first calculation formula is shown in the following formula (1): In the above equation (1), Tc is the conductor temperature of the cable, Tenv is the ambient temperature, I is the cable current carrying capacity, R20 is the conductor resistance at 20°C, Kc is the conductor temperature coefficient, Rthc is the thermal resistance between the conductor and the jacket, Rthj is the thermal resistance of the jacket, the armor and the filler material between them, Rtho is the thermal resistance of the outer jacket, Rthenv is the thermal resistance of the environment surrounding the cable, Uc is the voltage carried by the cable, Ric is the insulation resistance per unit length of the cable; The first temperature calculation model further comprises a second calculation formula for calculating the surface temperature of the cable, and the second calculation formula is shown in the following formula (2): In the above formula (2), T is the surface temperature of the cable; In the step S1, the second temperature calculation model is constructed according to the conductor loss, the dielectric loss and the inductive loss of the cable; The second temperature calculation model comprises a third calculation formula for calculating the conductor temperature of the cable, and the third calculation formula is shown in the following formula (3): In the above equation (3), Tc is the conductor temperature of the cable, Tenv is the ambient temperature, Ic is the cable current-carrying capacity, R is the conductor ac resistance per unit length at maximum current-carrying capacity, Rth is the thermal resistance between the conductor and the jacket, Rj is the thermal resistance of the jacket, armor, and filler material between the two, Rj is the thermal resistance of the jacket, armor, and filler material between the two, Renv is the thermal resistance of the cable's surrounding environment, D is the dielectric loss, n is the number of current-carrying conductors, M is the ratio of the metal shield loss to the conductor loss, A is the ratio of the armor layer loss to the conductor loss; The second temperature calculation model further comprises a fourth calculation formula for calculating the surface temperature of the cable, and the fourth calculation formula is shown in the following formula (4): In the above formula (4), is the surface temperature of the cable.

2. The method of claim 1, wherein: The step S3 is to compare and verify the calculation value of the step S2 by using the actual measurement value of the surface temperature and the conductor temperature of the cable; the actual measurement value of the surface temperature of the cable is obtained from a thermocouple arranged on the surface of the cable, and the actual measurement value of the conductor temperature of the cable is obtained from a thermocouple arranged on the conductor of the cable.

3. An apparatus, said apparatus being an electronic device, characterized in that: The device comprises a memory and a processor which are coupled to each other, and the processor is used to execute program instructions stored in the memory to realize the method for simulating and calculating the surface temperature and the conductor temperature of the cable according to any one of claims 1 to 2.

4. A medium, which is a computer-readable storage medium, having stored thereon program instructions, characterized in that: The program instructions are executed by the processor to realize the method for simulating and calculating the surface temperature and the conductor temperature of the cable according to any one of claims 1 to 2.

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