Application of online partial discharge detection of switchgear based on ultra-high frequency method

Ultra-High Frequency (UHF) method is one of the most effective methods for partial discharge (PD) detection of HV switchgear, due to its high sensitivity and strong resistance to external interference. Despite of these advantages, it is still uneasy to realize the accurate identification of the fault types and discharge stages of HV switchgear owning to the lack of a systematic research and analysis on the partial discharge characteristics of different defects in switchgear. In this paper, three typical partial discharge defect models, including needle discharge, suspended discharge, and internal discharge were designed. The PRPD spectra of different discharge defect models at various discharge stages were obtained by application of UHF method. The results demonstrated that based on the characteristics of the PRPD spectra of various discharge defect model, the type of PD could be effectively recognized by analyzing the characteristic variables of the PRPD spectra. Moreover, the discharge stages could also be roughly inferred from the diversity of different PRPD spectra. Therefore, UHF provides an effective way to evaluate the defect type and stage of PD in HV switchgear.