Dielectric properties and thermal conductivity of micro-BN-modified LSR used for high-voltage direct current cable acces
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Dielectric properties and thermal conductivity of micro-BN-modified LSR used for high-voltage direct current cable accessories Qingguo Chen1 · Banggen Xi1 · Jinfeng Zhang2 · Hongda Yang1 · Xinyu Wang1 · Minghe Chi1 Received: 23 May 2020 / Accepted: 8 August 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract Thermal breakdown is the main form which leads to direct current (DC) cable accessories insulation invalid. In order to enhance the insulation of DC cable accessories, liquid silicone rubber (LSR) is improved by filling micron boron nitride (BN) to promote the dielectric properties and thermal conductivity in this paper. The electrical conductance, DC dielectric breakdown strength (DBS), dielectric spectrum and thermal conductivity of micro-BN/LSR composites with various filling concentrations are analyzed in combination with the charge-trap energy-level distributions by means of isothermal surface potential decay (ISPD) method. By filling micron BN into LSR, the insulation performance and thermal conductivity can be improved simultaneously, thus achieving a higher insulation reliability. When the concentration of BN micron-filler is increased to 40 wt%, the electrical conductivity can be reduced by three orders of magnitude compared with pure LSR, and the DC DBS and thermal conductivity rises by 52.82% and 141.38%, respectively, while the relative dielectric permittivity and dielectric loss are slightly increased. The ISPD analyses indicate that trap-level depth in BN/LSR composites can be further raised by increasing the concentration of BN micron fillers, thereby getting a higher DBS.
1 Introduction Compared with traditional alternating current (AC) power transmission, high-voltage direct current (DC) power transmission is widely used in asynchronous grid connection and long-distance transmission across the sea due to a variety of advantages such as constant short-circuit capacity, fast power adjustment, high system stability and low line loss [1–3]. As the physical foundation and key equipment of DC grid construction, high-voltage DC cables have been shown to have promising properties to be used in the smart grid and the future global power transmission [4, 5]. The insulation safety and reliability of the entire DC power transmission network rely on the insulation performances of cable accessories which are the essential parts of high-voltage DC * Minghe Chi [email protected] 1
Key Laboratory of Engineering Dielectrics and Its Application, Ministry of Education, Harbin University of Science and Technology, Harbin 150080, Heilongjiang, China
School of Electrical Engineering and Automation, Qilu University of Technology (Shandong Academy of Sciences), Jinan 250353, China
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cable system [6]. Due to the complex structure comprising multiple layers of composite insulation, cable accessories are attributed to the weakest and most valuable equipment in cable systems [7, 8]. Engineering experiences indicate that more than 70% of cable failures locate at the ca
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