CONFIDENTIAL – LIMITED USE · Specific accelerated ageing factor s, based on CIGRE TB496, were...

CONFIDENTIAL – LIMITED USE

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Testing experiences on extruded cable

systems up to 525kVdc in the first third

party worldwide laboratory

Uberto Vercellotti (Market & Product Development)

HVDC International Workshop – March 29th, 2017 Venice

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March 29, 2017 Venice ITALY

HVDC International Workshop

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Key features of the changing electrical market

In a changing electrical market, driven by renewable energies, the target is to get wind or solar energy to the consumption centers.In the EU but also in the USA and Far East they are talking about HVDC Super-Grid capable of transporting energy over thousands of kilometers with minimal losses, helping and in some cases supplanting the old network in HVAC.

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Key features of the changing electrical market

65 Billion $ investment in HVDC will be required within 2020 to support the evolution of the renewables energy scenario.

Only in the last 3 years we doubled the length of the connections made in the previous 50 years.

Meanwhile in the next decade MKTof HV submarine cables is estimated at $ 25 billion, about 3/4 of the projects located in EU both ongoingconnections or in the planning or

feasibility study phase.

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According to Dr. Volker Wendt, Director of Public Affair of Europacable

Changing in EU electrical market

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But there are some bottlenecks

So priority is to undergroundingAn example of best practice is the German cable legislation Dec 2015� 16 pilot projects for HVAC partial undergrounding� Priority to undergrounding for new HVDC projects.


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The role of Third Parties Assessment

Independent third party like CESI and others can play an active role in ensuring standards keep pace with industry demands, be based on different inputs from:the manufacturers who have knowledge of the product, the utilities and TSO who have the know-how of the end use of products and experts who can set up the relevant testing program.

Involvement in National &International bodies like IEC, ISO,STL reassures customers their components are tested � the latest and most relevant standards by people who really understand the contestof those standards.

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How to increase the quality level of cables systems

Independent testing and certification provided by a third party is the way to grant:

Aim of a qualification process for a cable systems is to:

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Type Tests performed to verify suitable characteristics to meet application,

PQ performed to assess (reliable and safe) long term performance of the complete cable system, simulating(at least) 30 years of service:During execution severe heating cycles are combined with higher voltage application.

This creates accelerating aging conditions for HV cables � improper material handling & processing during manufacturing are enhanced.

Qualification goes through:

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Never under evaluate the importance of “accessories”, that shown to be the weak part of the system: an accessory has to handle the high electrical stresses in the cable insulation and next to this to cope with thermo-mechanical forcesexerted by cables.

Despite ongoing improvements in material and production the failure rate is not decreasing (many surveys show still 20 to 50% of all TT on accessories result in failure).

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The best way to improve component

quality is Independent Testing and

Certification, in order to

meet the basic safety,

reliability and performance

levels required for the use in

the network.

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Critical issue when testing cables

Critical issues when testing HV cables

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Recent developments in testing HVDC extruded cables

HV cables & accessories are insulated with cross-linked polyethylene (XLPE), High-performance Polypropylene Thermoplastic Elastomer, Ethylene Propylene Rubber (EPR), Mass Impregnated (MI), or paper/oil-based cables.

XLPE cable was the largest segment in the underground cable systems market in 2015-6.

HVDC is also a new challenge for HV extruded Cables systems up to 525kV.

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At the September 2014 Mannheim symposiumthat precede the opening of HVDC new test lab in FGH,TSO emphasized a lack of multi-year experience with HVDC technology, especially in the HV cable sector making it necessary to verify solutions under extreme operational conditions, like Polarity Reversal sequences.

From this point of view, CESI’s new testing facilities 25 x 60 x 21(h) m in size,

up to 3 independent areas (25 x 20 m each), can help conduct additional experiments, increasing the reliability of the grids.

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Within this respect, the first part of a TERNA research program to compare the behavior of different HVDC extruded cables design solutions in case of polarity reversal withstand, has been recently accomplished.

Specific accelerated ageing factors, based on CIGRE TB496, were selected together with accelerated test duration & the number of polarity reversal stress to be performed. The tests performed showed that HVDC cables with extruded insulationcan withstand voltage polarity reversal even with sustained voltage polarity reversals section.

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In order to have higher thermal and electrical performance (e.g. operating temperature and higher power deliverable), TSO are looking for a new class of extruded cables able to reach 525 kVdc.

In particular the German TSO, in the frame of the Energiewende, are looking for a first set of cable manufacturers able to supply at least 3000kmof 525kVdc cable systemsafter a relevant qualification process where CESI is deeply engaged (TT and PQT):4 loops will be tested in FGH.

2 GW

4 GW

2 GW

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Main laboratories in Milano Laboratories IPH in Berlin

Laboratories FGH in Mannheim

HVDC International Workshop - Venice 29/03/2017

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Many thanks for your attention

Any questions ?

HVDC International Workshop - Venice 29/03/2017

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Milano • Berlin • Mannheim • Dubai • Rio de Janeiro • Washington

CONFIDENTIAL – LIMITED USE · Specific accelerated ageing factor s, based on CIGRE TB496, were...

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