Electrical treeing in power cable insulation under harmonics superimposed on unfiltered HVDC voltages

Mehrtash Azizian Fard*, Mohamed Emad Farrag, Alistair Reid, Faris Al-Naemi

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

11 Citations (Scopus)
91 Downloads (Pure)


Insulation degradation is an irreversible phenomenon that can potentially lead to failure of power cable systems. This paper describes the results of an experimental investigation into the influence of direct current (DC) superimposed with harmonic voltages on both partial discharge (PD) activity and electrical tree (ET) phenomena within polymeric insulations. The test samples were prepared from a high voltage direct current (HVDC) cross linked polyethylene (XLPE) power cable. A double electrode arrangement was employed to produce divergent electric fields within the test samples that could possibly result in formation of electrical trees. The developed ETs were observed via an optical method and, at the same time, the emanating PD pulses were measured using conventional techniques. The results show a tenable relation between ETs, PD activities, and the level of harmonic voltages. An increase in harmonic levels has a marked effect on development of electrical trees as the firing angle increases, which also leads to higher activity of partial discharges. This study of the influencing operational parameters of HVDC converters on power cable insulation is predicted to contribute to enhancements in cable design and progressive advancement in condition monitoring and insulation diagnostic techniques that can lead to more effective asset management in HVDC systems.
Original languageEnglish
Article number3113
Number of pages15
Issue number16
Publication statusPublished - 14 Aug 2019


  • Degradation
  • Electrical trees
  • HVDC transmission
  • Harmonics
  • Insulation
  • Partial discharges
  • Polymers
  • Power cable insulation


Dive into the research topics of 'Electrical treeing in power cable insulation under harmonics superimposed on unfiltered HVDC voltages'. Together they form a unique fingerprint.

Cite this