The insulation performance of Epoxy resin (EP), the main material of insulators used in high voltage equipment, is related to the operation state of power system. Under high voltage, the properties of EP will change by time, thus the development of partial discharges (PD) will be different. This paper is aimed at revealing the development of surface discharge of EP. In this paper, recurrence characteristics of PD optical signals and UHF signals under constant voltage are calculated. An optic-electric sensing platform for PD detection was built based on ultra-high frequency (UHF) antenna and silicon photomultiplier (SiPM). Then the PD detection experiment was carried out at 1.1 times of partial discharge inception voltage (PDIV) of EP. Recurrence quantitative analysis (RQA) is finally used to extract average recurrence rates of phase sequence (RR₁) and amplitude sequence (RR₂) of PD. In traditional sense, average PD numbers(N) and average PD amplitude(A) would decrease in the long run (as in Fig.1(a),(b)). However, in Fig.1(c), both RR₁ and RR₂ increase over time, which can be selected as an indicator of PD intensity. Besides the analysis results of the UHF signal and the optical signal are verified the same. The proposed recurrence analysis method reflect the intensity of PD. In the future, the variation range and growth rate of recurrence characteristics can be obtained through repeated tests to estimate the aging degree of EP.
 

Epoxy resin (EP),Surface Discharge,Recurrence Plots