CN-121978434-A - Conductor coated submarine cable current-carrying capacity prediction method based on thermal resistance theory

CN121978434ACN 121978434 ACN121978434 ACN 121978434ACN-121978434-A

Abstract

The invention relates to the technical field of sea cable current-carrying capacity prediction, in particular to a conductor coated sea cable current-carrying capacity prediction method based on a thermal resistance theory, which comprises the steps of connecting lead sleeves and armor shorts at two ends of a conductor uncoated steel wire sea cable with two different grounding points of a test site through grounding leads respectively, and treating a conductor copper wire coated aluminum alloy armor sea cable prototype in the same way; heating the submarine cable under a preset current value of a test loop, setting the current of the test loop as a test current value, acquiring and recording submarine cable characteristic data, adjusting the test current value and repeatedly recording a plurality of groups of data, calculating each part of thermal resistance based on the plurality of groups of submarine cable characteristic data and a thermal circuit formula, calculating the dielectric loss, inputting each part of thermal resistance and the dielectric loss into a preset submarine cable current-carrying capacity prediction model to obtain the submarine cable current-carrying capacity output by the submarine cable current-carrying capacity prediction model.

Inventors

FU JINGHAN
LIU ZONGXI
CHEN XIAOYUE

Assignees

武汉大学
中国电力科学研究院有限公司

Dates

Publication Date: 20260505
Application Date: 20260120

Claims (8)

1. The method for predicting the current-carrying capacity of the conductor coated submarine cable based on the thermal resistance theory is characterized by comprising the following steps of: The lead sleeves and armoring short circuits at the two ends of the conductor non-coated steel wire submarine cable are respectively connected with two different grounding points of a test site through grounding leads, and the conductor copper wire coated aluminum alloy armoring submarine cable prototype is processed in the same way; Heating the submarine cable under a preset current value of a test loop, setting the current of the test loop as a test current value after reaching a target temperature, acquiring and recording submarine cable characteristic data after the temperature of a conductor is stable, adjusting the test current value, and repeatedly recording a plurality of groups of data; Calculating the thermal resistance of each part based on a plurality of groups of submarine cable characteristic data and a thermal path formula, and calculating to obtain dielectric loss; inputting the thermal resistance and the dielectric loss of each part into a preset submarine cable current-carrying capacity prediction model to obtain the submarine cable current-carrying capacity output by the submarine cable current-carrying capacity prediction model.
2. The method for predicting the current-carrying capacity of the conductor coated submarine cable based on the thermal resistance theory according to claim 1, wherein the step of shorting the lead sleeves and armors at the two ends of the conductor uncoated steel wire submarine cable comprises the following steps: when the lead sleeve short circuit is completed by adopting a lead pipe welding method, symmetrically processing cutting edges of lead jackets at two ends of a joint and the lead jackets, selecting a lead pipe with the inner diameter slightly larger than the outer diameter and the length of the lead jackets, which can cover the joint and form effective lap joint with original lead jackets at two ends, sleeving the lead pipe on a submarine cable joint, welding one end of the lead pipe and the lead jackets of a submarine cable body by using oxyhydrogen flame matched with a lead welding rod, drawing the lead pipe by using a drawing die with the inner diameter sequentially reduced after the welding is completed until the outer diameter of the lead pipe is consistent with the lead jackets, and then welding the other end of the lead pipe; A connecting sleeve welding method is adopted for the armor short circuit, a wrapping unit outside an armor steel wire at the end part of a submarine cable is stripped to expose the steel wire, a connecting sleeve with the length of 8-15cm and a convex middle section and connecting sections at two sides is selected, a first section of the connecting sleeve is inserted into the end part of the first submarine cable, the armor steel wire is sleeved on the periphery of the first section, the end part of the steel wire is welded with the side wall of the middle section, the armor steel wire of a second submarine cable passes through a through hole corresponding to a pitch disc, the original pitch of the armor steel wire is restored by rotating the pitch disc, the steel wire is sleeved on the periphery of the second section of the connecting sleeve, the end part of the armor steel wire is welded with the other side wall of the middle section after the redundant steel wire is cut, and the short circuit between lead sleeves at two ends of the submarine cable and the armor is completed.
3. The method for predicting the current-carrying capacity of the conductor coated submarine cable based on the thermal resistance theory according to claim 2, wherein the conductor uncoated steel wire submarine cable is characterized in that a copper wire conductor and a steel wire armor are adopted, the length is 15m, and the section of the conductor is 1000mm 2 ; The conductor copper wire coated aluminum alloy armored submarine cable prototype adopts copper wire conductor coated films and aluminum alloy wire armor, the length is 15m, and the conductor section is 1000mm 2 .
4. The method for predicting the current-carrying capacity of the conductor coated submarine cable based on the thermal resistance theory according to claim 3, wherein the current value of the preset test loop is 2500A, and the test current value is 500A.
5. The method for predicting the current-carrying capacity of a conductor coated submarine cable based on a thermal resistance theory according to claim 4, wherein the submarine cable characteristic data comprise conductor temperature, sheath temperature, armor temperature, environment temperature, sheath circulation and armor circulation.
6. The method for predicting the current-carrying capacity of a conductor coated submarine cable based on thermal resistance theory according to claim 5, wherein the steps of adjusting the test current value and repeatedly recording a plurality of sets of data comprise: And respectively raising the test loop current to 700A and 900A, respectively measuring and recording the conductor temperature, the sheath temperature, the armor temperature, the environment temperature, the sheath circulation and the armor circulation data of each temperature measuring point, and generating a characteristic data table based on the measured data.
7. The method for predicting the current-carrying capacity of a conductor coated submarine cable based on a thermal resistance theory according to claim 6, wherein the calculating the thermal resistance of each part based on the plurality of groups of submarine cable characteristic data and the thermal path formula and the calculating the dielectric loss comprises: Calculating conductor loss The expression is: ; ; Wherein, the For alternating current in the high voltage conductor, For the ac resistance per unit length of the high voltage conductor at operating temperature, For the dc resistance per unit length of the high voltage conductor at operating temperature, As a result of the skin effect factor, Is a proximity effect factor; Calculating total loss of metal sheath and armor : ; ; Wherein, the Is the parallel equivalent resistance of the sheath and the armor, Is the resistance of the metal sheath in unit length of the submarine cable at the highest working temperature, The resistance of the armoured sheath per unit length of submarine cable at the highest working temperature, And The sheath inductive reactance and the steel wire inductive reactance are respectively; for an alternating current submarine cable armored by adopting a non-magnetic material, calculating the proportion of sheath loss to conductor loss And the proportion of armoured losses to conductor losses The expression is: ; ; Wherein, the For total loss of metal sheath and armor The proportion of conductor loss; for an alternating current submarine cable armored by magnetic materials, calculating the proportion of sheath loss to conductor loss And the proportion of armoured losses to conductor losses The expression is: ; The thermal resistance of each part is calculated, and the expression is: ; Wherein, the Respectively the thermal resistance between a single conductor and a metal sleeve, the thermal resistance of an inner liner layer between the metal sleeve and an armor, the thermal resistance of an outer sheath of a submarine cable and the thermal resistance between the surface of the submarine cable and surrounding medium, 、、、 The temperature of the conductor, the temperature of the sheath, the temperature of the armor and the ambient temperature are respectively; Three groups of test data are calculated based on three groups of test data of the characteristic data table And carrying out data precision correction by adopting a weighted average method to obtain single-group thermal resistance data after data correction.
8. The method for predicting the current-carrying capacity of the conductor coated submarine cable based on the thermal resistance theory according to claim 7, wherein the equation of the current-carrying capacity I of the submarine cable output by the submarine cable current-carrying capacity prediction model is obtained by inputting the thermal resistance data and the dielectric loss of each part into a preset submarine cable current-carrying capacity prediction model, and the equation is as follows: 。

Description

Conductor coated submarine cable current-carrying capacity prediction method based on thermal resistance theory Technical Field The invention relates to the technical field of submarine cable current-carrying capacity prediction, in particular to a conductor coated submarine cable current-carrying capacity prediction method based on a thermal resistance theory. Background The current-carrying capacity of the submarine cable is used as a core index for measuring the power transmission capacity of the submarine cable, and the efficiency and the safety of energy transmission are directly related. The sea cable current-carrying capacity is accurately mastered, the sea cable can be ensured to stably run within the design life, serious problems such as overheat, insulation aging, fault short circuit and the like of the sea cable caused by overload are avoided, the persistence of energy transmission is guaranteed, and huge maintenance cost and energy supply interruption risk caused by faults are reduced. Under the background of continuous rising of energy demands and vigorous development of new energy industries such as offshore wind power and the like, the sea cable current-carrying capacity is accurately tested and optimized, and the method has important significance for improving the development and utilization efficiency of ocean energy and promoting energy green transformation. However, there is still a problem in the existing submarine cable current-carrying capacity test method, especially in the submarine cable current-carrying capacity test of air laying, because the air has fluidity, the heat dissipation condition is complex and changeable, and accurate control and simulation are difficult, which makes it extremely difficult to accurately measure the temperature distribution around the submarine cable. Meanwhile, the conventional thermocouple is insufficient in temperature measurement precision, when the temperature of the submarine cable conductor is measured, the submarine cable conductor is easily interfered by external environment, the measurement error is large, the current is difficult to precisely control, the temperature of the submarine cable conductor is stabilized at 90 degrees, the calculation precision of the current-carrying capacity is directly affected by inaccuracy of the conductor temperature, and the reliability of the current-carrying capacity result obtained based on the measurement data is reduced. Disclosure of Invention The invention aims to provide a conductor coated submarine cable current-carrying capacity prediction method based on a thermal resistance theory, which solves the problems of easiness in external environment interference, larger measurement error and low reliability in the prior art. In order to achieve the above purpose, the invention provides a conductor coated submarine cable current-carrying capacity prediction method based on a thermal resistance theory, which comprises the following steps: The lead sleeves and armoring short circuits at the two ends of the conductor non-coated steel wire submarine cable are respectively connected with two different grounding points of a test site through grounding leads, and the conductor copper wire coated aluminum alloy armoring submarine cable prototype is processed in the same way; Heating the submarine cable under a preset current value of a test loop, setting the current of the test loop as a test current value after reaching a target temperature, acquiring and recording submarine cable characteristic data after the temperature of a conductor is stable, adjusting the test current value, and repeatedly recording a plurality of groups of data; Calculating the thermal resistance of each part based on a plurality of groups of submarine cable characteristic data and a thermal path formula, and calculating to obtain dielectric loss; inputting the thermal resistance and the dielectric loss of each part into a preset submarine cable current-carrying capacity prediction model to obtain the submarine cable current-carrying capacity output by the submarine cable current-carrying capacity prediction model. In some embodiments of the application, shorting the lead sleeves at the two ends of the conductor uncoated steel wire submarine cable with armor comprises: when the lead sleeve short circuit is completed by adopting a lead pipe welding method, symmetrically processing cutting edges of lead jackets at two ends of a joint and the lead jackets, selecting a lead pipe with the inner diameter slightly larger than the outer diameter and the length of the lead jackets, which can cover the joint and form effective lap joint with original lead jackets at two ends, sleeving the lead pipe on a submarine cable joint, welding one end of the lead pipe and the lead jackets of a submarine cable body by using oxyhydrogen flame matched with a lead welding rod, drawing the lead pipe by using a drawing die with the inner diameter sequentially reduc