Controlling the thermal environment in hot spots of buried power cables

Klimenta, Dardan; Nikolajevic, S.V.; Sredojevic, M.R.

doi:10.1002/etep.133

Cited by 11 publications

(12 citation statements)

References 5 publications

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“…In order to avoid possible overheating of the cables pulled through the plastic pipes or cables laid in the concrete ducts in the zones A and B, a free convection (natural air ventilation) in pipes and ducts could be provided [11]. Likewise, the overheating problem of the cables laid in the soil of Zone C can be successfully solved by the use of the pure quartz sand or other thermally stable beddings [11].…”

Section: Resultsmentioning

confidence: 98%

“…Based on the bedding materials proposed in Reference [11], the cable bedding that can be used for a simultaneous prevention of both overheating and mechanical damage is also suggested. The cable bedding is composed of: (1) river sand with a high percentage of quartz and fine-grained aggregates of the particles 0-4 mm (about 60-70%), (2) gravel with fine-grained aggregates of the particles 4-16 mm (about 30-40%) and (3) cement (2%).…”

Section: Resultsmentioning

confidence: 99%

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FEM modelling of faults occurred in buried power cables due to the removal of tree roots

Klimenta¹,

Kuč²,

Raičević³

et al. 2010

Int Trans Elec Energy Syst

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SUMMARYAn engineering approach to numerical modelling of power cable heating due to a line-to-earth short-circuit caused by previous mechanical damages of a cable sheath and insulation is proposed in this paper. Nonlinearity of the finite element model is based on the soil thermal conductivity and heat sources as functions of temperature and time. The nonlinear transient analysis is applied to an authentic example of line-to-earth shortcircuit caused by a mechanical damage of the cable sheath and insulation that has arisen during the previous removal of tree roots. The represented fault occurred on 14 November 2007 in a buried 0.4 kV cable line installed in the city of Bijelo Polje, Republic of Montenegro. Also, this paper outlines a proposition of a technical report prescribing procedures for the removal of tree roots from the soil surrounding cables and for laying power cables nearby high vegetation. The proposed engineering approach is applicable to power cables of all voltage levels laid in soils with changeable moisture content.

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Section: Resultsmentioning

confidence: 98%

Section: Resultsmentioning

confidence: 99%

FEM modelling of faults occurred in buried power cables due to the removal of tree roots

Klimenta¹,

Kuč²,

Raičević³

et al. 2010

Int Trans Elec Energy Syst

Self Cite

View full text Add to dashboard Cite

show abstract

“…But the formulas are used for specific cable constructions and formations and are not usable and precise in complicated cases. Therefore, some other methods based on finite element method (FEM) and finite difference method were used, which are appropriate and accurate in complicated configurations . Ampacity calculation of high‐voltage cables with copper metallic screens and considering the trench surface is performed by FEM in 1 study .…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, some other methods based on finite element method (FEM) and finite difference method were used, which are appropriate and accurate in complicated configurations. 10,11 Ampacity calculation of high-voltage cables with copper metallic screens and considering the trench surface is performed by FEM in 1 study. 12 Moreover, magnetic eddy current and thermal coupled FEM model is used in 1 study, 13 but sheath layer and grounding type are not considered.…”

Section: Introductionmentioning

confidence: 99%

Calculation of losses and ampacity derating in medium-voltage cables under harmonic load currents using finite element method

Rasoulpoor

Mirzaie

Mirimani

2016

Int. Trans. Electr. Energ. Syst.

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Summary This paper investigates the influence of metallic sheaths on alternating current (AC) losses and ampacity of power cables. The AC losses are expressed as AC/direct current (DC) resistance in power cables, which is the main factor in loss computations. With regard to the importance of harmonic contents of the currents, a comprehensive study is performed on AC/DC resistance of medium‐voltage cables in the presence of harmonics. Different harmonic frequencies include triple and nontriple orders are considered. A derating factor is proposed on the basis of cable constructions. Two types of sheathed and unsheathed medium‐voltage power cables are considered. Also for metallic sheathed cables, 2 types of sheath grounding are investigated. It is shown that single‐point bonding and both‐ends bonding of sheaths have different effects on cable ampacity in harmonic frequencies. Moreover, different conductor cross sections and distances between cables are considered, and their effects on AC/DC resistance and ampacity derating are assessed. It is shown that these factors have important effects on AC/DC resistance and thus power cable losses. Furthermore, all cases are investigated in both flat and trefoil formations that are the most popular formations in power cables. To achieve precise results, we performed this study on the basis of finite element simulation, which is an exact way to cable losses computations in each configuration.

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“…The flowcharts of the main programme and its nonlinear steady-state and transient solution modules are given in Reference[12], whereas the flowcharts of the modules for reading, generation and storing of input data and for linear steady-state analysis are shown inFigures 4 and 5, respectively. The sets of subroutines, which are organized into the aforementioned modules perform the numerous mathematical routines.…”

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confidence: 99%

Insulation modelling for thermal FEM analysis of PVC and XLPE cables under fault conditions

Klimenta¹,

Radosavljević²,

Jevtić³

et al. 2011

Int Trans Elec Energy Syst

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SUMMARY An approach to modelling of electrical and thermo‐physical properties in small cylindrical volumes of cable insulation, that is, insulation spot samples is presented in this paper. Apart from small leakage currents, high currents can flow through these spots under fault conditions, at the same time heating up and destroying the cable insulation in them as well. An introduction of models for electrical and thermo‐physical properties of the insulation to the nonlinear thermal finite element method (FEM) analysis of faults is demonstrated on the examples of short circuits that occurred in buried power cables. Nonlinearity of the thermal FEM model is based on the heat sources, electrical and thermo‐physical properties of polyvinyl‐chloride and cross‐linked polyethylene insulation as functions of temperature and/or time. According to the DIN VDE standards, the cable structures considered herein correspond to the NAYY 4×120 SM 0.6/1 kV and NA2XY 4×120 SM 0.6/1‐kV cables. The proposed models for insulation properties are applicable to the fault thermal FEM analysis of all multi‐core power cables laid in the soils, air or water. Copyright © 2011 John Wiley & Sons, Ltd.

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Controlling the thermal environment in hot spots of buried power cables

Cited by 11 publications

References 5 publications

FEM modelling of faults occurred in buried power cables due to the removal of tree roots

FEM modelling of faults occurred in buried power cables due to the removal of tree roots

Calculation of losses and ampacity derating in medium-voltage cables under harmonic load currents using finite element method

Insulation modelling for thermal FEM analysis of PVC and XLPE cables under fault conditions

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