Research On Transient Temperature Distribution Of Epoxy Insulating Material Under Pulse Heating

Saturable reactor is core protection elements of HVDC valve. The periodically turn-on process and the turn-off process of converter valve makes saturable reactor insulation influenced by periodic pulses of electric stress for a long term which easily leads to partial destruction of the micro structure in rapid impact thermal stress epoxy material and reduction of insulation performance. Currently, periodic pulse thermal stress of saturable reactors epoxy material and its insulation aging mechanism are not clear which has become a potential threat to HVDC reliability. Based on the above issues, this paper focuses on the thermal distribution calculation and fast temperature measurement of saturable reactor epoxy materials.1) Based on finite element analysis method of JMAG-Designer, the pulsed power heating model is established which implements accurate calculation of the transient temperature distribution of the internal material with microsecond magnitude.2) Domestic and foreign fast temperature measurement and sensor technology are systematically studied and compared with experiments. The separate fiber fast infrared temperature measurement platform based on IGA740-LO infrared temperature instrument is established which enhance temperature measurement response speed up to 6-9 microseconds;3) Utilize the impact of current generator, Cr20Ni80 Nichrome alloy sling as a power source and a heat source respectively. Transient temperature change of epoxy materials with different thicknesses is studied. The result shows that measured temperature curve is consistent with simulating calculation.This paper lays a solid foundation for insulation aging mechanism and life prediction of saturable reactors epoxy material with the combined effect of a periodic pulse electrothermal stress.