Calculation of thermal fields of underground cables using the boundary element method

Gela, G.; Dai, J.

doi:10.1109/61.193929

Cited by 61 publications

(16 citation statements)

References 8 publications

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“…For example, the rating of underground cables [7]; cables in a tray [8]; the effects of radiation, solar heating, duct structures, and back-filled materials [9]; and, the formation of the dry zone around underground cables [10] have been studied by FEM. Other numerical methods, including the finite difference method (FDM) [11] and the boundary element method (BEM) [12], have also been studied. The above numerical methods can generally model complicated laying conditions with high accuracy, but the thermal circuit is more suitable for meeting the demand of transient rating and online implementation [13].…”

Section: Introductionmentioning

confidence: 99%

Comparison of Conductor-Temperature Calculations Based on Different Radial-Position-Temperature Detections for High-Voltage Power Cable

et al. 2018

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Abstract:In this paper, the calculation of the conductor temperature is related to the temperature sensor position in high-voltage power cables and four thermal circuits-based on the temperatures of insulation shield, the center of waterproof compound, the aluminum sheath, and the jacket surface are established to calculate the conductor temperature. To examine the effectiveness of conductor temperature calculations, simulation models based on flow characteristics of the air gap between the waterproof compound and the aluminum are built up, and thermocouples are placed at the four radial positions in a 110 kV cross-linked polyethylene (XLPE) insulated power cable to measure the temperatures of four positions. In measurements, six cases of current heating test under three laying environments, such as duct, water, and backfilled soil were carried out. Both errors of the conductor temperature calculation and the simulation based on the temperature of insulation shield were significantly smaller than others under all laying environments. It is the uncertainty of the thermal resistivity, together with the difference of the initial temperature of each radial position by the solar radiation, which led to the above results. The thermal capacitance of the air has little impact on errors. The thermal resistance of the air gap is the largest error source. Compromising the temperature-estimation accuracy and the insulation-damage risk, the waterproof compound is the recommended sensor position to improve the accuracy of conductor-temperature calculation. When the thermal resistances were calculated correctly, the aluminum sheath is also the recommended sensor position besides the waterproof compound.

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Section: Introductionmentioning

confidence: 99%

Comparison of Conductor-Temperature Calculations Based on Different Radial-Position-Temperature Detections for High-Voltage Power Cable

et al. 2018

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“…It is essential to ensure effective dissipation of this energy to avoid excessive heating of the cable that could lead to its rupture. The study of the heat dissipated from the cable in the surrounding soil has been the subject of many works [1][2][3][4][5][6][7][8][9][10]. Previous works focused on the thermal behaviour of cable backfill materials, the ampacity of cables, the effect of the installation geometry including the dimensions of the trench, cable location and diameter, the thermal properties of the surrounding soils, the seasonal variation of temperature, etc.…”

Section: Introductionmentioning

confidence: 99%

Modelling of coupled heat and moisture flows around a buried electrical cable

2016

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Abstract. The admissible current within a buried electrical power cable is limited by the maximum allowed temperature of the cable (Joule effect). The thermal properties of the surrounding soil controls heat dissipation around the cable. The main focus of the study was to evaluate the coupled heat and moisture flow around such buried electrical cables. The heat dissipation of a buried power cable was simulated in the surrounding soil at unsteady conditions. The hydro-thermal coupling was modelled by taking into account the moisture flow of liquid water and vapour, and the heat flow in the soil by convection and advection. As the thermal vapour diffusion enhancement factor () appears to be a key parameter, the sensitivity study of the coupled heat and moisture flow in the ground regarding this parameter was performed. The variations of the degree of saturation and the temperature of the surrounding soil were studied over 180 days of heating. The results showed that the moisture flow was mainly caused by the vapour transport under temperature gradients. These results emphasized the significant effect of the hydrothermal characteristics of surrounding soil. The radius of influence of the power cable was also evaluated.

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“…Furthermore, power cable engineers need to calculate the thermal stress of cable insulations at given cable current so that the aging condition can be evaluated and the remained life can be predicted with high accuracy. Therefore, the thermal analysis of underground cable systems has received considerable attention in the last two decades [1][2][3][4][5][6][7][8].…”

Section: Introductionmentioning

confidence: 99%

“…In order to solve these problem, numerical techniques, such as boundary element [1], finite difference [2,3] and finite element method [12], have been applied to calculate the thermal field and the ampacity. Numerical methods not only allow a better representation of the heating interaction among cables, but also permit more accurate modeling of the boundaries of the various regions.…”

Section: Introductionmentioning

confidence: 99%

Steady-state thermal analysis of power cable systems in ducts using streamline-upwind/petrov-galerkin finite element method

Liang¹

2012

IEEE Trans. Dielect. Electr. Insul.

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In this paper, numerical steady-state thermal analysis and ampacity evaluation of underground power cable systems placed in PVC ducts are presented. Between the outer surface of the cable and inner surface of the duct, there are three heat transfer modes, thermal conduction, thermal natural convection and thermal radiation. A Streamline-upwind/Petrov-Galerkin (SUPG) stabilized finite element method is proposed to solve the air governing formulas including the mass conservation equation, the momentum conservation equation and the energy conservation equation in the region between the cables and the containment ducts. During the numerical thermal field analysis, the Newton-Raphson iteration method is used to solve the weak electromagnetic-thermal coupling of underground power cable systems. The radiation heat exchange between the outer surface of the cable and inner surface of the duct is solved by the Newton-Raphson iteration method too. An experiment with several holes and three cables was conducted and the test results were compared with the results of analytical method and SUPG finite element method. The comparison reveals that the convection induced heat exchange is much stronger than the conduction induced heat exchange in the air between the outer cable surface and inner duct surface and calculation accuracy of SUPG finite element method is better than the analytical method. Finally, the Newton-Raphson iteration method is used to evaluate the ampacity of power cable systems placed in PVC ducts.Index Terms -Thermal field, Finite element method, cable ampacity, underground cable system, coupling analysis, SUPG stabilized formulation.(2) A j J J J J

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Calculation of thermal fields of underground cables using the boundary element method

Cited by 61 publications

References 8 publications

Comparison of Conductor-Temperature Calculations Based on Different Radial-Position-Temperature Detections for High-Voltage Power Cable

Comparison of Conductor-Temperature Calculations Based on Different Radial-Position-Temperature Detections for High-Voltage Power Cable

Modelling of coupled heat and moisture flows around a buried electrical cable

Steady-state thermal analysis of power cable systems in ducts using streamline-upwind/petrov-galerkin finite element method

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