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Testing HVDC cables to improve electricity grids

Testing HVDC cables to improve electricity grids
15 . Dec . 2021

In Europe , already in 2030 the ten-year development plan of the EU grid foresees 58% of electricity from renewable sources in the EU mix to be tackled with 166 new grid development projects and 15 storage projects , for a total investment of 144 billion Euro, which will result in annual savings of from 2 to 5 million Euro, due to the cut in generation costs and due to the greater flexibility of the system .

In this respect, power generation from renewable energy sources and interconnection among networks are the two main areas where energy links is developing massively and as such are driving technological evolution. Cable market is one of the hot sectors in the clean energy transition, as demand for products such as undersea HV lines leads to order backlogs of 2 to 5 years for cable makers portfolios.

Therefore, T&D World , one of the main magazines dedicated to testing activities in the United States , dedicated an in-depth article to some key projects developed by KEMA Labs (the Testing, Inspection and Certification Division of CESI).

In particular, the article shows how “new KEMA Labs testing facilities in Mannheim, Germany , with 60 m x 25 m x 21 m (L x W x H) in size, with 3 independent areas (25 m x 20 m each), each one with a dedicated DC generator, can support through flexible and professional testing services the increase of reliability of the grids.”

In the article, as an example, the first set of cable manufacturers able to supply at least 3000km of 525 kV DC extruded cables systems was searched by German Transmission System Operators (GTSO), in the frame of the Energiewende. In this respect, an ad hoc qualification process was established by GTSO ( Type Tests and Pre-Qualification Tests ) where CESI was deeply engaged, and 4 cable loops were under test in FGH Mannheim. For the first time ever for HVDC cable systems , the cable loops of the PQT were not tested on the floor of a laboratory, but mainly underground, representing real network situations like urban tunnel, pipelines and joint bays.

Moreover, recently the KEMA Labs Mannheim laboratory was requested to perform a feasibility study on the possibilities of setting up test circuits that could enable laboratory testing of full-scale HVDC cable systems up to 525 kV according to the TOV . The aim was to verify the performance of the HVDC cable system to withstand these stresses, which are of non-standard nature e.g. during pole-to-ground fault, pole to pole fault, faults on AC side etc.

Finally, the article by T&D highlights how “the positive experiences gained from the tests carried out for the GTSO project and the growing requests from European and Far East manufacturers and utilities, have prompted KEMA Labs to invest in the Milan laboratory (called the Big Hall “il Salone”) with substantial interventions that have made it equipped now with two test lines for HVDC cable systems up to 525kV (both terrestrial and submarine cables), according to the most up-to-date international requests.

You can read the full article at this link .

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