CN-122020953-A - Temperature field and current-carrying capacity calculation method and terminal for double-loop heterogeneous submarine cable

CN122020953ACN 122020953 ACN122020953 ACN 122020953ACN-122020953-A

Abstract

The invention discloses a temperature field and current-carrying capacity calculation method and a terminal of a double-loop heterogeneous submarine cable, wherein the submarine cable is divided into a deep sea section, a shoal section and a landing section according to the laying environment of the submarine cable, the geometric complexity and calculation resource occupation of a single model are obviously reduced, a simulation model is built for each section, and a corresponding electromagnetic field, a heat transfer field and a fluid field are coupled, so that the heat radiation and convection heat transfer mechanism of the submarine cable in the environment of ocean currents, soil, concrete ditches and the like can be truly reproduced. An equivalent circuit is constructed for the double-loop heterogeneous submarine cable, loop current values are solved in each section of the submarine cable according to sheath impedance and armor impedance of the submarine cable, and the loop current values are injected into an electromagnetic field in the form of an equivalent current source. The step-by-step current rising method realizes accurate safe current-carrying capacity judgment through real-time conductor temperature feedback, and avoids over-design or potential temperature overrun risks. In this way, errors of cable temperature distribution and safe current-carrying capacity assessment in the simulation process are effectively reduced.

Inventors

CAI CHANGMING
XIE WEI
LIN ZHIXIONG
CHEN CHAOHUI
Luo Wangbin
YOU XIAOHUA
LI JINSEN
WANG JUNWEI
YAN YOUXIANG
CHEN HONG
ZHOU YUANXIANG
LV WEIWEI
Fu Xinya
SUN ZHIHONG
CHEN YANNI
XU HONGBIN

Assignees

国网福建省电力有限公司厦门供电公司
国网福建省电力有限公司
清华大学

Dates

Publication Date: 20260512
Application Date: 20251209

Claims (10)

1. The temperature field and current-carrying capacity calculation method of the double-loop heterogeneous submarine cable is characterized by comprising the following steps of: dividing the submarine cable into a deep sea section, a shoal section and a landing section according to the laying environment of the submarine cable; Establishing a simulation model for each section of the submarine cable, and coupling a corresponding electromagnetic field, a heat transfer field and a fluid field for each section of the simulation model to obtain an electromagnetic-heat-flow coupling model; Constructing an equivalent circuit for the double-loop heterogeneous submarine cable, solving a circulation value in each section of the submarine cable according to the sheath impedance and the armor impedance of the submarine cable, and injecting the circulation value into an electromagnetic field of the electromagnetic-thermal-current coupling model in the form of an equivalent current source; obtaining the temperature field distribution of the submarine cable by solving the electromagnetic-thermal-flow coupling model; and iteratively solving the electromagnetic-thermal-current coupling model by adopting a step-by-step current rising method, continuously monitoring the conductor temperature, and taking the current at the moment as the safe current-carrying capacity of the submarine cable when the conductor temperature reaches a preset safety threshold value.
2. The method of calculating the temperature field and the current capacity of a dual-loop heterogeneous submarine cable according to claim 1, wherein coupling the corresponding electromagnetic field, heat transfer field and fluid field for each segment of simulation model comprises: Coupling an electromagnetic field, a heat transfer field and a fluid field for a simulation model of the deep sea section; Coupling an electromagnetic field and a heat transfer field for a simulation model of the shoal section; coupling an electromagnetic field, a heat transfer field and a fluid field for the simulation model of the landing section; establishing electromagnetic-thermal coupling for the electromagnetic field and the heat transfer field coupled in each section of simulation model: Establishing a fluid heat transfer control equation for a heat transfer field and a fluid field coupled in a simulation model of the deep sea section and the landing section: where Q l denotes a heat source of the fluid material, ρ l denotes a density of the fluid, C P2 denotes a specific heat capacity of the fluid material at normal pressure, T denotes a temperature of the fluid, v denotes a velocity vector of the fluid, Q denotes a conduction heat flux, τ denotes a viscous stress tensor, and P denotes a pressure of the fluid.
3. The method for calculating the temperature field and the current-carrying capacity of the double-loop heterogeneous submarine cable according to claim 2, wherein the electromagnetic field and the heat transfer field coupled in each section of simulation model are subjected to electromagnetic-thermal coupling, and the method comprises the following steps: the electromagnetic loss of the electromagnetic field is used as a heat source and is applied to the wire core, the sheath and the armor of the submarine cable to obtain electromagnetic heat; the electromagnetic losses include: Heat loss of cable core conductor: Wherein R represents an effective value of conductor resistance under actual operation conditions of the cable core, and I c represents a current value of the conductor of the submarine cable core; dielectric loss by insulating material: Wherein f represents voltage frequency, c represents cable capacitance per unit length, U 0 represents voltage at the time of operation of the cable line, delta represents dielectric loss angle, tan delta represents loss factor of the insulating medium; Loss on jacket, armor: Wherein W s represents a submarine cable sheath loss, I si represents a circulating current generated on an ith submarine cable sheath, R si represents a unit impedance of the ith submarine cable sheath, W a represents a submarine cable armor loss, I ai represents a circulating current generated on the ith submarine cable armor, and R ai represents a unit impedance of the ith submarine cable armor.
4. The method for calculating the temperature field and the current-carrying capacity of the double-loop heterogeneous submarine cable according to claim 2, wherein an equivalent circuit is constructed for the double-loop heterogeneous submarine cable, a loop current value is calculated according to sheath impedance and armor impedance of the submarine cable in each section of the submarine cable, and the loop current value is injected in an electromagnetic field of the electromagnetic-thermal-current coupling model in the form of an equivalent current source, and the method comprises the following steps: constructing an equivalent circuit for each section of the submarine cable to obtain a circulation calculation equation: Wherein R s represents the total resistance of the submarine cable metal sheath, X s represents the total reactance of the submarine cable metal sheath, R a represents the total resistance of the submarine cable armor, X a represents the total reactance of the submarine cable armor, R sm +jX sm represents the impedance of the metal sheath of the submarine cable of the mth section, R am +jX am represents the impedance of the armor of the submarine cable of the mth section, U n si 、U n ai represents the total induced voltage of the metal sheath and the armor in the state n, U n sim 、U n aim represents the induced voltage of the metal sheath and the armor of the cable of the mth section in the state n; And dynamically calculating the circulation distribution of the sheath and the armor according to the circulation calculation equation, and introducing the circulation calculation equation into the electromagnetic field in the form of an equivalent current source to serve as a current boundary condition of the sheath and the armor.
5. The method for calculating the temperature field and the current-carrying capacity of the double-loop heterogeneous submarine cable according to claim 1, wherein the step-by-step current-up method is adopted to iteratively solve the electromagnetic-thermal-current coupling model and continuously monitor the conductor temperature, and when the conductor temperature reaches a preset safety threshold, the current at the moment is regarded as the safe current-carrying capacity of the submarine cable, and the method comprises the following steps: And (3) gradually increasing submarine cable current from the initial current value, monitoring conductor temperature, sheath circulation and armor circulation at the same time, stopping current rising when the conductor temperature reaches a preset safety threshold value, and regarding the current at the moment as the safety current-carrying capacity of the submarine cable.
6. The temperature field and current-carrying capacity calculation terminal of the double-loop heterogeneous submarine cable comprises a memory, a processor and a computer program which is stored in the memory and can run on the processor, and is characterized in that the following steps are realized when the processor executes the computer program: dividing the submarine cable into a deep sea section, a shoal section and a landing section according to the laying environment of the submarine cable; Establishing a simulation model for each section of the submarine cable, and coupling a corresponding electromagnetic field, a heat transfer field and a fluid field for each section of the simulation model to obtain an electromagnetic-heat-flow coupling model; Constructing an equivalent circuit for the double-loop heterogeneous submarine cable, solving a circulation value in each section of the submarine cable according to the sheath impedance and the armor impedance of the submarine cable, and injecting the circulation value into an electromagnetic field of the electromagnetic-thermal-current coupling model in the form of an equivalent current source; obtaining the temperature field distribution of the submarine cable by solving the electromagnetic-thermal-flow coupling model; and iteratively solving the electromagnetic-thermal-current coupling model by adopting a step-by-step current rising method, continuously monitoring the conductor temperature, and taking the current at the moment as the safe current-carrying capacity of the submarine cable when the conductor temperature reaches a preset safety threshold value.
7. The temperature field and current capacity computation terminal of a dual-loop heterogeneous submarine cable according to claim 6, wherein coupling corresponding electromagnetic fields, heat transfer fields and fluid fields for each segment of simulation model comprises: Coupling an electromagnetic field, a heat transfer field and a fluid field for a simulation model of the deep sea section; Coupling an electromagnetic field and a heat transfer field for a simulation model of the shoal section; coupling an electromagnetic field, a heat transfer field and a fluid field for the simulation model of the landing section; establishing electromagnetic-thermal coupling for the electromagnetic field and the heat transfer field coupled in each section of simulation model: Establishing a fluid heat transfer control equation for a heat transfer field and a fluid field coupled in a simulation model of the deep sea section and the landing section: where Q l denotes a heat source of the fluid material, ρ l denotes a density of the fluid, C P2 denotes a specific heat capacity of the fluid material at normal pressure, T denotes a temperature of the fluid, v denotes a velocity vector of the fluid, Q denotes a conduction heat flux, τ denotes a viscous stress tensor, and P denotes a pressure of the fluid.
8. The temperature field and current capacity calculation terminal of a dual-loop heterogeneous submarine cable according to claim 7, wherein establishing electromagnetic-thermal coupling for the electromagnetic field and the heat transfer field coupled in each simulation model comprises: the electromagnetic loss of the electromagnetic field is used as a heat source and is applied to the wire core, the sheath and the armor of the submarine cable to obtain electromagnetic heat; the electromagnetic losses include: Heat loss of cable core conductor: Wherein R represents an effective value of conductor resistance under actual operation conditions of the cable core, and I c represents a current value of the conductor of the submarine cable core; dielectric loss by insulating material: Wherein f represents voltage frequency, c represents cable capacitance per unit length, U 0 represents voltage at the time of operation of the cable line, delta represents dielectric loss angle, tan delta represents loss factor of the insulating medium; Loss on jacket, armor: Wherein W s represents a submarine cable sheath loss, I si represents a circulating current generated on an ith submarine cable sheath, R si represents a unit impedance of the ith submarine cable sheath, W a represents a submarine cable armor loss, I ai represents a circulating current generated on the ith submarine cable armor, and R ai represents a unit impedance of the ith submarine cable armor.
9. The temperature field and current capacity calculation terminal of a double-loop heterogeneous submarine cable according to claim 7, wherein an equivalent circuit is constructed for the double-loop heterogeneous submarine cable, a loop current value is solved in each section of the submarine cable according to sheath impedance and armor impedance of the submarine cable, and the loop current value is injected in an electromagnetic field of the electromagnetic-thermal-current coupling model in the form of an equivalent current source, comprising: constructing an equivalent circuit for each section of the submarine cable to obtain a circulation calculation equation: Wherein R s represents the total resistance of the submarine cable metal sheath, X s represents the total reactance of the submarine cable metal sheath, R a represents the total resistance of the submarine cable armor, X a represents the total reactance of the submarine cable armor, R sm +jX sm represents the impedance of the metal sheath of the submarine cable of the mth section, R am +jX am represents the impedance of the armor of the submarine cable of the mth section, U n si 、U n ai represents the total induced voltage of the metal sheath and the armor in the state n, U n sim 、U n aim represents the induced voltage of the metal sheath and the armor of the cable of the mth section in the state n; And dynamically calculating the circulation distribution of the sheath and the armor according to the circulation calculation equation, and introducing the circulation calculation equation into the electromagnetic field in the form of an equivalent current source to serve as a current boundary condition of the sheath and the armor.
10. The terminal for calculating the temperature field and the current capacity of the double-loop heterogeneous submarine cable according to claim 6, wherein the step-by-step current-up method is adopted to iteratively solve the electromagnetic-thermal-current coupling model and continuously monitor the conductor temperature, and when the conductor temperature reaches a preset safety threshold, the current at the moment is regarded as the safe current capacity of the submarine cable, and the terminal comprises: And (3) gradually increasing submarine cable current from the initial current value, monitoring conductor temperature, sheath circulation and armor circulation at the same time, stopping current rising when the conductor temperature reaches a preset safety threshold value, and regarding the current at the moment as the safety current-carrying capacity of the submarine cable.

Description

Temperature field and current-carrying capacity calculation method and terminal for double-loop heterogeneous submarine cable Technical Field The invention relates to the technical field of submarine cable evaluation, in particular to a temperature field and current-carrying capacity calculation method and a terminal of a double-loop heterogeneous submarine cable. Background The traditional thermal/electromagnetic simulation method of the submarine cable is mainly concentrated on a deep sea section, adopts a combined model of combining a steady electromagnetic field with Fourier heat conduction, but has the following defects: (1) Neglecting the effect of the fluid in the sea/soil on the thermal convection results in underestimating the thermal coupling between the deep sea section and the shoal section. (2) The model adopted for the shoal section and the landing section is only solid heat conduction coupling, and can not capture convection heat transfer generated by air flow in the cable trench. (3) The sheath and armor of the double-loop cable can generate circulation (loop currents) due to parallel operation, but the prior art mostly adopts a single-loop or simplified impedance method, and does not carry out sectional solution on each section, so that circulation distribution errors are accumulated. Because of the defects, larger errors often occur in the evaluation of the temperature distribution and the safe current-carrying capacity of the cable, and hidden troubles are brought to the design, operation maintenance and safety management of the system. Disclosure of Invention The invention aims to solve the technical problem of providing a temperature field and current-carrying capacity calculation method and a terminal of a double-loop heterogeneous submarine cable, which can reduce errors of cable temperature distribution and safe current-carrying capacity assessment. In order to solve the technical problems, the invention adopts the following technical scheme: A temperature field and current-carrying capacity calculation method of a double-loop heterogeneous submarine cable comprises the following steps: dividing the submarine cable into a deep sea section, a shoal section and a landing section according to the laying environment of the submarine cable; Establishing a simulation model for each section of the submarine cable, and coupling a corresponding electromagnetic field, a heat transfer field and a fluid field for each section of the simulation model to obtain an electromagnetic-heat-flow coupling model; Constructing an equivalent circuit for the double-loop heterogeneous submarine cable, solving a circulation value in each section of the submarine cable according to the sheath impedance and the armor impedance of the submarine cable, and injecting the circulation value into an electromagnetic field of the electromagnetic-thermal-current coupling model in the form of an equivalent current source; obtaining the temperature field distribution of the submarine cable by solving the electromagnetic-thermal-flow coupling model; and iteratively solving the electromagnetic-thermal-current coupling model by adopting a step-by-step current rising method, continuously monitoring the conductor temperature, and taking the current at the moment as the safe current-carrying capacity of the submarine cable when the conductor temperature reaches a preset safety threshold value. In order to solve the technical problems, the invention adopts another technical scheme that: the temperature field and current-carrying capacity calculation terminal for the double-loop heterogeneous submarine cable comprises a memory, a processor and a computer program which is stored in the memory and can run on the processor, wherein the processor realizes the steps of calculating the temperature field and the current-carrying capacity of the double-loop heterogeneous submarine cable when executing the computer program. The invention has the advantages that the submarine cable is divided into a deep sea section, a shoal section and a landing section according to the laying environment of the submarine cable, the geometric complexity and the computing resource occupation of a single model are obviously reduced, and a simulation model is built for each section and is coupled with a corresponding electromagnetic field, a heat transfer field and a fluid field, so that the heat radiation and convection heat transfer mechanism of the submarine cable in the environments of ocean currents, soil, concrete ditches and the like can be truly reproduced. An equivalent circuit is constructed for the double-loop heterogeneous submarine cable, loop current values are solved in each section of the submarine cable according to sheath impedance and armor impedance of the submarine cable, and the loop current values are injected into an electromagnetic field in the form of an equivalent current source. The step-by-step current rising method realizes accur