Method for calculating current carrying capacity of directly-buried single-core cable considering soil local dryness

A single-core cable, local drying technology, used in computing, electrical digital data processing, special data processing applications, etc., can solve problems such as difficulty in ensuring calculation accuracy, and achieve the effect of facilitating calculation and reducing errors

Inactive Publication Date: 2015-05-27
SOUTH CHINA UNIV OF TECH
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, it is difficult to guarantee the calculation accuracy if the current carrying capacity of the direct-buried cable is calculated according to the thermal resistance of the first layer.

Method used

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  • Method for calculating current carrying capacity of directly-buried single-core cable considering soil local dryness
  • Method for calculating current carrying capacity of directly-buried single-core cable considering soil local dryness
  • Method for calculating current carrying capacity of directly-buried single-core cable considering soil local dryness

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Embodiment

[0037] Such as Figure 5 As shown, in this embodiment, a method for calculating the ampacity of a direct-buried single-core cable considering local dryness of the soil includes the following steps:

[0038] S1. Modeling the cable body. The structure of a single-core cable is as figure 1 As shown, it includes conductor core 1 , conductor shielding layer 2 , XLPE insulating layer 3 , insulating shielding layer 4 , paper wrapping tape 5 , air gap layer 6 , aluminum sheath 7 and outer sheath 8 from inside to outside. Based on modeling assumptions: when the cable is running, its geometric parameters are constant; without considering the axial heat transfer, the cable is considered to be a one-dimensional heat conduction process; the surface of the cable outer sheath is an isothermal surface. The conductor AC loss, insulation dielectric loss and sheath loss are respectively expressed by the heat flow Q 1 , Q 2 , Q 3 Indicates; ignoring the influence of metal shielding and insul...

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Abstract

The invention discloses a method for calculating current carrying capacity of a directly-buried single-core cable considering soil local dryness. The method comprises the following steps of S1, modeling a directly-buried single-core cable body to obtain a thermal circuit model of the directly-buried single-core cable body; S2, building a thermal circuit model with local dry soil and natural soil double layers for the external soil of the directly-buried single-core cable; S3, connecting the thermal circuit model of the cable body and the thermal circuit model of the external soil, so as to obtain the thermal circuit model of the directly-buried single-core cable; S4, solving the thermal circuit model, and calculating, so as to obtain the current carrying capacity of the directly-buried single-core cable considering the local dryness condition. The method has the advantage that the external soil of the directly-buried cable is divided to obtain a local dryness boundary which is coaxial with the cable body, and the actual soil heat transfer property is approximated by heat resistances of the local dry soil and natural soil double layers, so the simplicity and feasibility are realized, and the calculating is convenient.

Description

technical field [0001] The invention relates to the field of calculation of the ampacity of electric cables, in particular to a method for calculating the ampacity of direct-buried single-core cables considering local dryness of the soil. Background technique [0002] Compared with overhead lines, power cables are mostly laid underground by direct burial, piping, tunnels, etc., which not only guarantees the safety performance of power transmission, but also saves a lot of land resources. With the rapid development of cities, urban land is becoming increasingly scarce, and it has become a major trend for power cables to replace overhead lines for urban power supply. The biggest problem facing power cables in operation is how to determine their ability to transmit electric energy, that is, how to accurately calculate the current carrying capacity. [0003] At present, there are many methods for calculating the ampacity. IEC60287 provides calculation formulas for the ampacity ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G06F19/00
Inventor 刘刚王振华
Owner SOUTH CHINA UNIV OF TECH
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