Determination of the current carrying capacity of cables using the finite element method

Nahman, J.; Tanaskovic, M.

doi:10.1016/s0378-7796(02)00003-2

Cited by 42 publications

(27 citation statements)

References 2 publications

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“…The present paper uses an enhanced version of the previously mentioned model, which now incorporates also the effects of the heat transfer by radiation and solar emission, to evaluate the loading capacity of a pair of three-phase cable systems sharing the same trench. These two phenomena partially compensate each other at specific ambient condition, which explains the good behavior of the model suggested in [8] when compared with experimental results [9]. However, the model presented in this paper accounts for all processes affecting the heating of cables and, therefore, can be applied in all ambient conditions appearing in practice.…”

Section: Introductionmentioning

confidence: 60%

“…The mathematical model developed in [8] is enhanced by including the radiation and solar emission effects, for completeness. In Eq.…”

Section: Transient Temperature Equationmentioning

confidence: 99%

“…By discretization for a minor step t Eq. (6) converts into a simple recurrent relationship for determining temperature variation in time [8,11] […”

Section: Transient Temperature Equationmentioning

confidence: 99%

“…In [7], this method has been used for the analysis of the temperature rise of cables in case of step function loads, by assuming a uniform environment. A more complex model that takes into account the real shape and structure of cables and trench has been elaborated in [8]. The present paper uses an enhanced version of the previously mentioned model, which now incorporates also the effects of the heat transfer by radiation and solar emission, to evaluate the loading capacity of a pair of three-phase cable systems sharing the same trench.…”

Section: Introductionmentioning

confidence: 99%

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Evaluation of the loading capacity of a pair of three-phase high voltage cable systems using the finite-element method

Nahman

Tanaskovic²

2011

Electric Power Systems Research

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Section: Introductionmentioning

confidence: 60%

“…The mathematical model developed in [8] is enhanced by including the radiation and solar emission effects, for completeness. In Eq.…”

Section: Transient Temperature Equationmentioning

confidence: 99%

“…By discretization for a minor step t Eq. (6) converts into a simple recurrent relationship for determining temperature variation in time [8,11] […”

Section: Transient Temperature Equationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Evaluation of the loading capacity of a pair of three-phase high voltage cable systems using the finite-element method

Nahman

Tanaskovic²

2011

Electric Power Systems Research

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“…Such a model has also been elaborated for the evaluation of the ampacity of cables laid inside retaining ducts [9]. The finite element model for the evaluation of the ampacity of underground cables, elaborated in reference [10], has taken into account the drying out of soil and the heat transfer by convection from the soil surface. An enhanced version of this model, elaborated in reference [11], incorporating the radiation and solar heating effects.…”

Section: Introductionmentioning

confidence: 99%

Calculation of the ampacity of high voltage cables laid in free air

Tanaskovic¹

2018

Tehnika

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due to step function loads for cables laid in uniform environment [7]. A finite element mesh generator for thermal analysis of underground cables has been suggested [8], considering only the heat transfer by conduction. Such a model has also been elaborated for the evaluation of the ampacity of cables laid inside retaining ducts [9]. The finite element model for the evaluation of the ampacity of underground cables, elaborated in reference [10], has taken into account the drying out of soil and the heat transfer by convection from the soil surface. An enhanced version of this model, elaborated in reference [11], incorporating the radiation and solar heating effects. The latter model, for determining the current rating of the bunch of self-supporting insulated 10 kV cables, adequately adapted in reference [12], has been applied in this paper for comparison with analytical approaches. FINITE-ELEMENT MODEL Mathematical modelThe general form of the transient temperature equation for the subspace of cables under consideration, partitioned into a network of finite elements with N nodes, isCALCULATION OF THE AMPACITY OF HIGH VOLTAGE CABLES... 90TEHNIKA -ELEKTROTEHNIKA 67 (2018) 1 [C] is N by N heat capacitance matrix, [K] is N by N heat conductance, natural and forced convection and radiation matrix and [R(t)] is N dimensional heat load vector stemming from the internal heat generation, surface convection, and solar heating. Parameter matrices in (1) are In (1), [J(t)] is N dimensional column vector of temperatures of nodes,Indices c, h, r and s in (2) and (3) refer to conduction, convection, radiation and solar heating, respectively [11]. Index Q refers to the internal heat generation. The Joule losses in phase conductors and metallic sheaths have been taken into account as well as the dielectric losses in the insulating materials. Triangular finite elements have been used in this analysis.The matrices figuring in (1) -(3) have been obtained by transferring the corresponding relationships for elements written for their nodes in local coordinates [11] to entire network numbering scheme. Expressions (2) and (3) The coefficient matrices in equations (1) -(3) for a triangular element, in its local coordinates, are as given in [7, 10, 11, and 13]. They are complemented by relationships for heat load vector from specified surface heating, radiation and solar heating (Appendix A).After discretization for a minor step Dt, (1) converts into a simple recurrent relationship for determining temperature variation in time [13] )] (with g as the integration stability factor. In this analysis g=1 and Dt=2 min have been adopted, assuring a good accuracy for modest calculation time.The expressions for determination of characteristic parameters figuring in (1) Linear approximation of the heat transfer by radiationThe heat flux emitted by the radiation from a body at temperature ϑ equals

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Thermal analysis of the influence of harmonics on the current capacity of medium‐voltage underground power cables

Gouda

Dein

Eldin

et al. 2023

Energy Science & Engineering

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In this article, an algorithm is proposed and used to study the influence of harmonics on the behavior of medium‐voltage underground cables in flat formation. The proposed algorithm is a thermal model based on the heat equilibrium of the thermal circuit nodes of the medium‐voltage cable system. The impact of harmonics on the temperature rise of the cable elements and the cable capacity is evaluated in this article. Also, the impact of harmonics on the derating factors of cable for different soil types is presented. Finally, the measurement of temperatures of cable cores is carried out experimentally and compared with the calculated results to validate the proposed algorithm. One of the algorithm merits is that several harmonic percentages can be taken into account for each cable phase individually, and the heat exchange between the cable phases and their sheath is also taken into consideration. From the obtained results, it is illustrated that the presence of harmonics has a remarkable influence on the cable core temperature; mainly, harmonics of the third and fifth orders may lead to dry zone formation around the cable. It is also observed that the presence of harmonics has an important influence on the cable current, especially when it is buried in soil that has high thermal resistivity during the summer season (suction tension = ∞). In summer, the cable core temperature reached 152.162°C, 139.053°C, and 133.375°C when lime, sand, and silty sand, respectively, are used as backfill materials, rather than 90°C in the normal operating condition of the 11 kV three‐phase single‐core cable. It is observed also that with the increase of the soil thermal resistivity, the ratio of /) reached about 1.2 times at 2.5 K m/W soil thermal resistivity. In addition, it is also observed that the impact of harmonics leads to a percentage reduction in the derating factor of the cable center phase by 11.88%–12.37% depending on the composition of the backfill materials.

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Determination of the current carrying capacity of cables using the finite element method

Cited by 42 publications

References 2 publications

Evaluation of the loading capacity of a pair of three-phase high voltage cable systems using the finite-element method

Evaluation of the loading capacity of a pair of three-phase high voltage cable systems using the finite-element method

Calculation of the ampacity of high voltage cables laid in free air

Thermal analysis of the influence of harmonics on the current capacity of medium‐voltage underground power cables

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