Characterization of partial discharge in composite insulation system with PPLPR for HTS cable

Abstract

High-temperature Superconducting (HTS) cable systems with high power density and low loss are expected to be a solution for improving the power grid. Many researchers have worked on the development of the HTS cable. For insulation testing it is necessary to consider a partial discharge (PD) which is generated in butt gaps of the insulation layers. The electrical insulation system of HTS cables consists of liquid nitrogen (N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> (l)) and polypropylene laminated paper (PPLP). N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> 2 (l) cooling system is installed in the power system and N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> 2 (l) will flow through the cables after their installation in the system. Filling the HTS cable with N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> 2 (l) in order to perform pre-shipment inspection is costly for cable manufacturers. Therefore, they are trying to find a cost effective method for pre-shipment inspections. One alternative is to use atmospheric pressure air or N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> 2 (g) instead of N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> 2 (l) for pre-shipment inspections. This paper discusses PD characteristics in a butt gap of HTS cables in different environment such as atmospheric pressure air or N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> 2 (g) composite insulation. The results are compared with PD characteristics in N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> 2 (l)/PPLP to find the difference between insulation material in PD characteristics. High temperature superconducting cable, partial discharge, polypropylene laminated paper, insulation system.