On-site tests for the withstand voltage of lightning impulse of gas-insulated metal-enclosed switchgear（GIS）

which can effectively detect concentrative defects

has become an important part of GIS on-site withstand voltage tests. Therefore

we developed a model for the system of testing the withstand voltage of ultra-high-voltage GIS on-site lightning impulse by the ATP-EMTP transient analysis software based on the 1 100 kV GIS on-site withstand voltage test project of 1 000 kV Nanjing Ultra-high-voltage Substation. Moreover

we investigated the influences of test schemes selection method and the test conditions on the voltage waveform. The results show that the standard lightning impulse voltage waveform can be generated by regulating the wavefront resistance when the load capacitance is smaller than 7 000 pF; however

when the load capacitance is greater than 7 000 pF

the standard lightning impulse cannot be obtained. If the single-circuit-breaker connecting mode is adopted

we can get a higher waveform quality

but the efficiency is relatively lower. If the multi-circuit-breaker connecting mode is adopted

higher efficiency can be acquired at the expense of waveform quality. The introduction of external voltage divider will slightly decrease the voltage amplitude and make the wave-front time longer. As the length of high voltage wire between bushing increases

the wave-front time is slightly shortened

and simultaneously causes the oscillation of load voltage waveform. Thus

the 20 m-long wire is suggested to be adopted.