Measurement study of UHF local discharge based on voltage division method

Partial discharges represent a common initiation process for insulation deterioration and aging in electrical equipment within power systems, posing a threat to both the longevity and secure operation of insulated apparatus. Therefore, precise measurement of partial discharges holds critical significance. In this study, we introduce a measurement approach for extracting partial discharges through voltage division utilizing zinc oxide valves. The zinc oxide valve sheet is linked to the current sensor as a coupling capacitor, facilitating the execution of partial discharge tests on 110KVgrade Gas Insulated Switchgear (GIS) equipment through a step-by-step voltage method. Simultaneously, we compare the partial discharge monitoring results of the pulse current method, Ultra High Frequency (UHF) method, and ultrasonic method to ascertain the discharge patterns and trends associated with GIS defects. Additionally, we conduct a comparative analysis of the observation outcomes derived from the three testing methodologies employed in this study. The findings indicate that the UHF method exhibits heightened sensitivity, effectively mitigates electromagnetic wave interference, and proves suitable for the measurement of partial discharges. Conversely, while the zinc oxide valve sheet extraction method demonstrates simplicity and sensitivity, it is significantly susceptible to environmental factors, where the surrounding background noise significantly impacts measurement precision.