Advertisement

Electrical Engineering

, Volume 101, Issue 4, pp 1295–1309 | Cite as

Eliminating the effect of hot spots on underground power cables using cool pavements

  • Dardan KlimentaEmail author
  • Dragan Tasić
  • Bojan Perović
  • Jelena Klimenta
  • Miloš Milovanović
  • Ljiljana Anđelković
Original Paper
  • 20 Downloads

Abstract

It is well known that hot spots limit the ampacities of underground power cables. There are many commonly applied methods to control the thermal environment in hot spots of underground power cables. However, applications of cool pavements for this specific purpose would be a novelty in the field of power cable engineering. This paper considers the use of different cool pavements in combination with thermally stable bedding and/or pure quartz sand for mitigating or eliminating the thermal effect of an actual hot spot on the ampacities of a 110 kV cable line and a group of four 35 kV three-core cables installed in Belgrade, the Republic of Serbia. In the hot spot, the 110 kV cable line is installed in parallel with the group of 35 kV cables and crosses a district heating pipeline. All distances between these underground installations are lower than the recommended ones, and the 110 kV and 35 kV cables are laid at depths greater than required. The mutual thermal effects between the underground installations in the hot spot are simulated using FEM-based models for different environmental conditions. An experimental background is also provided. In comparison with the corresponding base cases, it has been found that the ampacities of the 110 kV cable line and group of 35 kV cables can be increased up to 25.1% and 60.9% in summer, and up to 62.8% and 170% in winter, respectively.

Keywords

Ampacity Cool pavement Finite element method (FEM) Hot spot Power cable Thermal effect 

List of symbols

Variables and coefficients

dc

Conductor diameter (m)

h

Heat transfer coefficient due to convection [W/(m2 K)]

I

Load current (A)

Icp

Cable ampacity (A)

k

Thermal conductivity [W/(m K)]

n

Length of the normal vector \( \vec{n} \) (m)

QS,s

Solar irradiance incident on the earth surface (W/m2)

Qv

Volume power of heat sources (W/m3)

q0

Specified heat flux on the upper surface of the heating-pipe duct (W/m2)

Rac

Effective conductor resistance to the flow of alternating current, i.e. effective a.c. resistance (Ω/m)

\( S_{\text{c}}^{\prime} \)

Geometric cross-sectional area of conductor (m2)

T

Unknown temperature or unknown surface temperature (K)

Ta

Temperature of the air contacting the earth surface (K or °C)

Tc,max

Temperature of the most thermally loaded conductor (°C)

Tcp

Continuously permissible temperature of cables (°C)

va

Wind velocity (m/s)

x, y

Cartesian spatial coordinates (m)

α

Solar absorptivity (dimensionless)

ε

Thermal emissivity (dimensionless)

σSB

Stefan–Boltzmann constant [W/(m2 K4)]

Abbreviations

2D and 3D

Two-dimensional and three-dimensional

EUR and €

National currency of the European Union member states

FEM

Finite element method

HDPE

High-density polyethylene

NA2XS(FL)2Y

Single-core power cable, N—standardised/norm type, A—aluminium conductor, 2X—cross-linked polyethylene insulation, S—copper screen, FL—longitudinally and crosswise water-tight, and 2Y—polyethylene outer sheath

NAEKEBA

Three-core power cable, N—standardised/norm type, A—aluminium conductor, EK—metal sheath of lead with corrosion protection on each sheath, E—thermoplastic sheath and inner protective covering, lapped bedding with additional layer of plastic tape, B—armour of steel tape, and A—outer protection of fibreous material (jute) in compound

PE

Polyethylene

PQS

Pure quartz sand

SI

International System of Units

TSB

Thermally stable bedding

XLPE

Cross-linked polyethylene

Notes

Acknowledgements

This paper was based on research conducted within the project TR33046 funded by the Ministry of Education, Science, and Technological Development of the Republic of Serbia. Also, the authors would like to thank Aleksandra D. Kuč for her technical assistance.

References

  1. 1.
    Klimenta D, Jevtić M, Klimenta J, Perović B (2018) A review on new methods for increasing the ampacity of underground power cables: cool and photovoltaic pavements. In Proceedings of the 6th international conference on renewable electrical power sources (6th ICREPS), pp 15–21Google Scholar
  2. 2.
    Klimenta D, Perović B, Klimenta J, Jevtić M, Milovanović M, Krstić I (2018) Modelling the thermal effect of solar radiation on the ampacity of a low voltage underground cable. Int J Therm Sci 134:507–516CrossRefGoogle Scholar
  3. 3.
    Klimenta D, Perović B, Klimenta J, Jevtić M, Milovanović M, Krstić I (2018) Controlling the thermal environment of underground cable lines using the pavement surface radiation properties. IET Gener Transm Distrib 12(12):2968–2976CrossRefGoogle Scholar
  4. 4.
    Klimenta DO, Perović BD, Klimenta TLJ, Jevtić MM, Milovanović MJ, Krstić ID (2018) Controlling the thermal environment of underground power cables adjacent to heating pipeline using the pavement surface radiation properties. Therm Sci 22(6):2625–2640CrossRefGoogle Scholar
  5. 5.
    Klimenta D, Jevtić M, Klimenta J, Perović B (2018) The effect of solar radiation on the ampacity of an underground cable with XLPE insulation. In Proceedings of the 4th virtual international conference on science, technology and management in energy (eNergetics 2018), pp 197–204Google Scholar
  6. 6.
    Klimenta D, Jevtić M, Milovanović M (2018) Comparing the effects of solar heating on low voltage underground cables with PVC and XLPE insulations. In: Proceedings of the 47th international scientific forum “Week of Science SPbPU”-2018, Part 2, pp 24–26Google Scholar
  7. 7.
    IEC (2014) IEC Standard Electric Cables-Calculation of the Current Rating-Part 1-1: Current Rating Equations (100% Load Factor) and Calculation of Losses-General, 2.1 edn. IEC 60287-1-1:2006 + AMD1:2014 CSVGoogle Scholar
  8. 8.
    IEC (2003) IEC technical report electric cables-calculations for current ratings-finite element method, 1st edn. IEC TR 62095:2003Google Scholar
  9. 9.
    Anders GJ (2005) Rating of electric power cables in unfavorable thermal environment, 1st edn. Wiley, HobokenGoogle Scholar
  10. 10.
    Nahman J, Tanaskovic M (2011) Evaluation of the loading capacity of a pair of three-phase high voltage cable systems using the finite-element method. Electr Power Syst Res 81(7):1550–1555CrossRefGoogle Scholar
  11. 11.
    Nahman J, Tanaskovic M (2013) Calculation of the ampacity of high voltage cables by accounting for radiation and solar heating effects using FEM. Int Trans Electr Energy Syst 23(3):301–314CrossRefGoogle Scholar
  12. 12.
    Nahman J, Tanaskovic M (2018) Calculation of the loading capacity of high voltage cables laid in close proximity to heat pipelines using iterative finite-element method. Int J Electr Power Energy Syst 103:310–316CrossRefGoogle Scholar
  13. 13.
    Terracciano M, Purushothaman S, de León F, Farahani AV (2012) Thermal analysis of cables in unfilled troughs: Investigation of the IEC standard and a methodical approach for cable rating. IEEE Trans Power Deliv 27(3):1423–1431CrossRefGoogle Scholar
  14. 14.
    Yang L, Qiu W, Huang J, Hao Y, Fu M, Hou S, Li L (2018) Comparison of conductor-temperature calculations based on different radial-position-temperature detections for high-voltage power cable. Energies 11(117):1–17Google Scholar
  15. 15.
    Lindström L (2011) Evaluating impact on ampacity according to IEC-60287 regarding thermally unfavourable placement of power cables. Masters’ Degree Project, Royal Institute of Technology (KTH), Stockholm, Sweden, XR-EE-ETK 2011:009Google Scholar
  16. 16.
    Klimenta D, Nikolajević S, Sredojević M (2007) Controlling the thermal environment in hot spots of buried power cables. Eur Trans Electr Power 17(5):427–449CrossRefGoogle Scholar
  17. 17.
    Klimenta D, Perovic B, Jevtic M, Radosavljevic J, Arsic N (2014) A thermal FEM-based procedure for the design of energy-efficient underground cable lines. Human Sci Univ J Tech 10:162–188Google Scholar
  18. 18.
    COMSOL (2012) Heat transfer module user’s guide. Version 4:3Google Scholar
  19. 19.
    Heinhold L (1990) Power cables and their application-Part 1, Third revised edn. Siemens Aktiengesellschaft, BerlinGoogle Scholar
  20. 20.
    Huebner KH, Dewhirst DL, Smith DE, Byrom TG (2001) The finite element method for engineers, 4th edn. Wiley, New YorkGoogle Scholar
  21. 21.
    Salata F, Nardecchia F, Gugliermetti F, de Lieto Vollaro A (2016) How thermal conductivity of excavation materials affects the behavior of underground power cables. Appl Therm Eng 100:528–537CrossRefGoogle Scholar
  22. 22.
    Salata F, Nardecchia F, de Lieto Vollaro A, Gugliermetti F (2015) Underground electric cables a correct evaluation of the soil thermal resistance. Appl Therm Eng 78:268–277CrossRefGoogle Scholar
  23. 23.
    Salata F, de Lieto Vollaro A, de Lieto Vollaro R (2015) A model for the evaluation of heat loss from underground cables in non-uniform soil to optimize the system design. Therm Sci 19(2):461–474CrossRefGoogle Scholar

Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2019

Authors and Affiliations

  • Dardan Klimenta
    • 1
    Email author
  • Dragan Tasić
    • 2
  • Bojan Perović
    • 1
  • Jelena Klimenta
    • 3
  • Miloš Milovanović
    • 1
  • Ljiljana Anđelković
    • 1
  1. 1.University of Priština in Kosovska MitrovicaKosovska MitrovicaSerbia
  2. 2.University of NišNišSerbia
  3. 3.ProElectric SDKraljevoSerbia

Personalised recommendations