Effect of AC Voltage Frequency on Partial Discharge Characteristics of GIS

In recent years, the development of advanced power electronic technology has created favorable conditions for high-voltage and high-power converters, and power transmission is no longer limited to the traditional power frequency, and low-frequency transmission system has become an important direction of power development in the new century. Partial discharge (PD) is an important index of insulation state evaluation of electrical equipment. The on-line detection and fault diagnosis evaluation of PD under low frequency environment are still lacking of engineering practice and reference standards. Therefore, this paper takes power GIS equipment as the object, designs four typical insulation defects, and conducts partial discharge experiments from 20Hz to 100Hz based on UHF method. The discharge characteristics of typical GIS insulation defects under low frequency environment and power frequency environment are compared and analyzed. PDIV, PDEV, discharge phase, pulse repetition rate, discharge amplitude and other parameters of partial discharge change with frequency were compared and analyzed. Meanwhile, the difference between low frequency and power frequency discharge spectrum was studied, providing reference for GIS partial discharge type diagnosis at low frequency.