AC Voltage Withstand Test Method and Risk Suppression Measures of Energized GIS Based on Phase-frequency Control

It is essential to carry out an AC voltage withstand test after GIS extension and maintenance. At present, the common methods of GIS AC withstand test include double isolation gap, reduce the test voltage, and narrow test range. These methods generally have some defects: such as complex test processes, all bus de-energized, some apparatus failed to test, unreliable test results and so on. This paper presents a distinctive GIS AC voltage withstand test method. The method controls the phase-frequency parameters of the test voltage so that it maintains the same phase-frequency relationships as the in-service bus voltage during the process of testing. In this situation, the GIS can carry out an energized AC voltage withstand test. The process of AC withstand voltage test method based on phase-frequency control (PFC) is introduced in detail, and the feasibility of this method is verified. The phase difference margin of the PFC method is optimized through simulation and numerical calculation, and a variety of protection measures are proposed to ensure the safety of the test process. The proposed PFC AC voltage withstand test method will not affect the in-service bus and has great practical application value for the field GIS AC voltage withstand test.0 _F .