January 23，By Graduate School of Shandong University、Sponsored by the Postgraduate Affairs Department of the Party Committee，The first issue of 2024 (the 1338th issue in total) "Jixiafeng" graduate student academic forum hosted by the School of Electrical Engineering was held in the lecture hall on the fourth floor of the Electric Power Building on Qianfoshan Campus。This forum invites Gilbert Teyssèdre, a senior researcher at the French National Center for Scientific Research (CNRS)，The topic of the lecture is "Challenges for insulating materials in HVAC and HVDC cables"。The forum is hosted by Associate Professor He Dongxin，Associate Professor Gong Jinlin、Associate Professor Jin Chaoyang、Associate Researcher Ren Fuqiang、International Exchange Specialist Wu Ke attended this event。

The lecture mainly focuses on insulated cables in the power grid、Dielectrics and related phenomena and challenges expanded into three parts，Systematically introduces the challenges faced by high-voltage AC and DC transmission cable insulation materials。First，Gilbert Teyssèdre via Grid Demand、The historical perspective of high-voltage cable technology and cable insulation introduces the insulated cables in the power grid from three aspects。He pointed out，HVDC transmission technology is a response to the needs of the power grid，Compared to AC cable，DC cables can in principle be used to transmit power over longer distances。He compared the two main types of high-voltage cables so far - oil-paper insulated cables and extruded insulated cables，Oil-paper insulated cable technology is very mature，Very high service reliability，Large capacity available、Long distance for undersea and land transmission；Extruded insulated cables have higher conductor temperatures (90°C)、Lighter vapor barrier、Easier to connect，And can reduce insulation loss and increase system length (not limited by oil pressure)。

Then Gilbert Teyssèdre introduced dielectrics and related phenomena，Including macroscopic response of dielectrics、Charge transport properties、Phenomena of insulating space charge。Dielectrics are capable of polarization、Materials capable of storing electrostatic energy，Also an insulator。When combining materials (or media) together，The electric field is redistributed based on conductivity (the electric field is higher in materials with greater resistance) or dielectric constant (the electric field is higher in materials with a lower dielectric constant)，Generally speaking，Solid insulating materials require low dielectric constant。In macro behavior，Dielectric constant、Loss and conductivity have different effects on stress distribution in insulating materials。Traps are an essential feature of transport in insulating materials，It includes physical traps and chemical traps。Later, he introduced the space charge measurement technology from the two methods of thermal and acoustics and their related principles。final，Gilbert Teyssèdre from General Trends、Introducing the challenges facing future cables and accessories from three aspects: accessory design and improved insulation materials。

Event last，Participating teachers and students took photos together。This issue of the "Jixiafeng" postgraduate academic forum ended successfully with warm applause from teachers and students。

About the speaker:

Gilbert Teyssèdre，Senior Researcher at the French National Center for Scientific Research (CNRS)，Mainly engaged in research in the field of solid insulation space charge and degradation mechanism，Served as the Solid Dielectrics and Reliability group of the Laplace Laboratory of the University of Toulouse, France from 2003 to 2015 , DSF) Research Group Director、Member of the Academic Committee of Laplace Laboratory, University of Toulouse, France。Served as a member of the Technical Steering Committee of the European Space and Aeronautical Science and Technology Network since 2012，And serves as the leader of several EU and French key scientific research projects。