HVDC cable systems (cables, joints and terminations)

About This Committee

The scope of the HVDC cable systems committee is developing IEEE Standards for testing HVDC extruded cable systems (cables, joints and terminations). The focus of the committee is on the following subtopics:

  • Lightning and switching impulse tests based on a proper selection of the level and the polarity of impulse voltage.
  • Load cycle tests based on a proper selection of the level and duration of test voltages (check of CIGRE brochures).
  • Cable characterization in prequalification and type tests, including protocols for space charge measurements, crosslinking by-products evaluation, and other effective parameters for diagnosis.
  • Polarity reversal test.
  • Weathering tests on composite terminations.

Additional Information About  The HVDC Cable Systems Technical Committee

Traditionally, high voltage DC (HVDC) cable systems have been viewed as the best solution for long-distance submarine transmission links. However, and more recently, the improved performance of AC/DC converters and the environmental concerns of overhead lines have made HVDC cable transmission more and more attractive worldwide. All of this has led to a quasi-exponential growth of installed HVDC cable lines worldwide, particularly in the last two decades. In this scenario, the relatively new HVDC extruded cable systems, have become more and more competitive compared with the traditional mass-impregnated nondraining HVDC extruded cable systems, although the latter has totalled much more service experience and at voltage and power ratings up to 500 kV and 1,000 MW per bipole. But, the former has some major advantages, namely, they are much more environmentally friendly because no oil is used in the insulation, the maximum permissible conductor temperature in normal operation is higher, and splicing is much easier. Starting from the early 1980s, and largely due to extensive and sound research and development, much of which was reported in the IEEE Dielectric and Electrical Insulation Society (DEIS) publications, the voltage and power ratings of installed HVDC extruded cable systems have increased, with bipolar DC extruded cable systems already in service at voltage and power levels up to 320 kV and 1 GW, respectively, and DC extruded cable systems being qualified at voltage ratings up to 600 kV.

In addition, the “Nemo Link,” which is a 130-km-subsea and 11.5-km-land 400-kV/1,000-MW XLPE HVDC cable system, is under construction between Richborough Energy Park in Kent (UK) and Zeebrugge (Belgium).

Today, extruded insulation for DC cables does not imply necessarily XLPE, as a new thermoplastic extruded insulation has been developed. This new insulation, which is not crosslinked, appears to be capable of withstanding a higher temperature and a higher stress. As it is not cross-linked, manufacturing time is reduced, and the insulation is fully recyclable and therefore more environmentally friendly.

It is in this context that in 2012 the then DEIS president, Simon Rowland, asked Giovanni Mazzanti to form the Technical Committee (TC) titled “HVDC cable systems (cables, joints, and termination). The first meeting of the TC was in Bologna, Italy, in July 2013, at the 2013 IEEE ICSD. Since then, the TC has been very active, with yearly meetings held at every IEEE CEIDP. The next meeting is scheduled on Sunday 21st October 2018 in Cancun, Mexico, seat of the 2018 IEEE CEIDP.

The first goal of the TC was to convert a protocol originally proposed in for measuring space charge in HVDC cables during qualification tests into an IEEE recommended practice. After a position paper was prepared on the method, IEEE Standard 1732 was issued in June 2017. In fact, the standard is the only approved IEEE standard to be developed by a DEIS TC this decade.

After completing this first task, the TC is now focusing on accessories, in particular on dedicated tests for joints. The TC will also follow closely the current revision of IEC Standard 62895 “High Voltage Direct Current (HVDC) power cables with extruded insulation and their accessories for rated voltages up to 320 kV for land applications—test methods and requirements”, as the extruded cable system has overcome the 320-kV barrier.

Land (left, photo courtesy of Prysmian) and submarine (right, photo courtesy of Sumitomo Electric) HVDC extruded cables.

Installed length of HVDC cable lines worldwide since 1950s

Current Activities

  • Selection of accessories – in particular joints for HVDC extruded cable systems – as the current topic for the technical committee to tackle
  • Focus on new techniques to characterize factory and premolded joints during routine tests
  • Refining a novel protocol to perform PD measurements under AC voltage on factory and pre-moulded joints for HVDC extruded cable systems during routine tests.

Recent Achievements

  • Writing of a Position Paper – G. Mazzanti, G. Chen, J. Fothergill, N. Hozumi, J. Li, M. Marzinotto, F. Mauseth, P. Morshuis, A. Tzimas, C. Reed, K. Wu, “A protocol for space charge measurements in full-size HVDC extruded cables”, IEEE Transactions on Dielectrics and Electrical Insulation, Vol. 22, N. 1, pp. 21-34, Feb.2015 – where a procedure for the measurement of space charge in prequalification and type tests for full-size HVDC extruded cable systems is proposed for the first time worldwide.
  • From the above Position Paper, writing, balloting, approval by IEEE SA, final editing and publication of Standard IEEE 1732-2017 entitled “IEEE Recommended practice for space charge measurements in High Voltage Direct Current extruded cables for rated voltages up to 550 kV” (June 2017). This is the first Standard document worldwide recommending a good practice for the measurement of space charge in qualification tests (prequalification and type tests) for full-size HVDC extruded cable systems.
  • Management of the Workshop on HVDC Extruded Cable Systems, held at IEEE CEIDP 2016 – Toronto, Ontario (Canada), on October 16th 2016. The workshop, chaired by Giovanni Mazzanti as being the chairman of the TC, was attended by 27 people. Apart from Thomas Andritsch (University of Southampton, UK), all other presenters are members of the TC/WG, i.e.: 1) Frank Mauseth (1 presentation), 2) Clive Reed (1 presentation), 3) Yasuhiro Tanaka (1 presentation), 4) Jerome Castellon (1 presentation), 5) Kai Wu (1 presentation), 6) Giovanni Mazzanti (4 presentations).
  • Publication of a Special Issue of the IEEE Electrical Insulation Magazine (vol. 33, no. 4, Jul./Aug. 2017) devoted to the Workshop on HVDC Extruded Cable Systems (IEEE CEIDP 2016). The presentations at the above-mentioned Workshop have been complied into 7 articles, plus and Editorial written by Giovanni Mazzanti, Guest Editor of the Special Issue as being the chairman of the TC.
  • Writing of two position papers for the June 2019 issue of the IEEE Transactions on Dielectrics and Electrical Insulation, entitled:
    I) The insulation of HVDC extruded cable system joints. Part 1: Review of materials, design and testing procedures

    II) The Insulation of HVDC Extruded Cable System Joints. Part 2: Proposal of a New AC Voltage PD Measurement Protocol for Quality Control during Routine Tests

Committee Members & Affiliation

No. Member Name Member Affiliation
1 Giovanni Mazzanti Chairman, University of Bologna, Italy
2 George Chen University of Southampton, UK
3 John Fothergill City University London UK
4 Mingli Fu China Southern Power grid, China
5 Naohiro Hozumi Toyohashi University of Technology, Toyohashi, Japan
6 June-Ho Lee Hoseo University, Korea
7 Jian Li Chongquing University, China
8 Massimo Marzinotto Terna, Italian TSO, Italy
9 Frank Mauseth NTNU-Trondheim University, Norway
10 Peter Morshuis Delft University, The Nederlands & “Solid dielectric solutions”
11 Clive Reed free consultant
12 Ivan Troia Prysmian Cables & Systems R&D Dept., Italy
13 Antonios Tzimas Advanced Energy, UK
14 Kai Wu Xi’an Jiaotong University, China
15 Yasuhiro Tanaka Tokyo City University, Japan
16 Jérôme Castellon University of Montpellier, France

For more information about this technical committee, please contact

Prof. Dr. Giovanni Mazzanti: giovanni.mazzanti@unibo.it