Characterization of defected PP insulating materials for DC cables from the NEWGEN project subjected to accelerated ageing

HVDC transmission is expected to play an increasingly important role in the development of renewable energy sources and in general in the energy transition to cope with the climate change. One of the most important elements of HVDC technology is the cable technology, with a particular accent on the insulating material, which probably constitutes the most critical aspect of the matter. Different materials and technologies have been utilized during the design and implementation of HVDC cables enhancing their properties, but nowadays there is a major difference: the market and the people are asking for more environmentally friendly compounds that could reduce significantly their polluting impact through recycling. This urgency paved the way to collaborations between the industry and the universities with the common goal of developing new materials for this always more essential technology; one example is NEWGEN, an international EU funded project, born with the intention of dealing with the matter. In this document, the author dealt with the electrical characterization of defected PP samples provided by VTT Technical Research Centre of Finland, a NEWGEN partner. Multiple electrical tests have been executed before and after the ageing of the samples to try to assess the impact of electrical stress, time and physical defects on the insulating properties of the material. The document begins with an introduction on the main technologies available for HVDC cables with a brief description of the effects that characterize them compared to those that work in AC conditions. A description of the tests’ setup performed follows; the conducted tests are: Pulsed Electro Acoustic method (PEA), Partial Discharge (PD) and conductivity measurement. Afterwards, the tests results are presented and conclusions are drawn. At the end of the document, a bit of theoretical insight is given concerning the tests.