Surface charge dissipation and DC flashover characteristic of DBD plasma treated epoxy resin/AlN nanocomposites

This paper presents the mechanism of the surface charge dissipation and flashover voltage of epoxy resin (EP) with nano aluminum nitride (AlN) composites enhanced by dielectric barrier discharge (DBD) plasma treatment in open air. Surface conductivity, surface potential decay (SPD), flashover voltage, Fourier transform infrared (FT-IR) and surface roughness were measured to evaluate the electrical and physicochemical properties of EP/AlN nanocomposite samples before and after the plasma treatments. It is found that surface conductivity is evidently increased with the increase of the plasma treatment time. Moreover, the SPD of the plasma treated samples after positive and negative corona charging are enhanced. However, the positive charge dissipation is influenced more significantly by the treatment. Both the positive and negative flashover voltage are improved after the plasma treatment, and the amplitude of negative flashover voltage is higher than the positive flashover voltage in each case. Physicochemical measurements show that the content of polar groups is improved after the plasma treatment, and the surface roughness is continuously increased with the increment of the plasma treatment time. The calculated trap distribution demonstrates that the amount of both shallow holes trap and shallow electron trap are increased after the plasma treatment. This investigation attributes the enhanced SPD and improved flashover voltage to the increased surface conductivity, the more amount of shallow traps and the improvement of the sample surface roughness.

1 Introduction

High voltage direct current (HVDC) transmission system has been widely used to increase the power system stability and transmitting the bulk power [1]. In the traditional HVDC transmission method, i.e. overhead lines and cables, epoxy resin (EP) is used in the fault current limiter or circuit breaker as an insulation under the high DC electric field and thermal stress [2]. State-of-the-art using the gas-insulated transmission lines (GIL) for the HVDC system includes the EP insulation [3]. Moreover, it supports the frame material between the high voltage conductor and the grounded enclosure under the DC electric field [4]. The critical operational issues such as the overload operation, partial discharges, fault current etc. in the overhead lines, cables and GIL will produce large heat ultimately aging the EP insulation [3].