Measurement And Analysis Of Very Fast Transient Overvoltage (VFTO) Induced By Operating Disconnector In 1000kV GIS

On the test platform of UHV GIS, thousands of disconnector operation tests were made by four test methods of two UHV GIS circuits. The distribution of UHV GIS VFTO during disconnector operations was got by using port hole sensor. And the characteristics of the waveform, the characteristics of distribution, effect of different structures on the VFTO and the maximum level of VFTO were firstly required.The results show that, resistance can greatly affect the VFTO. The maximum VFTO with resistance is 1.33pu, VFTO without resistance is 2.31pu. In addition, disconnector action speed impacts on VFTO, more slowly the speed, the low the trapped charge left of the last disconnector operation. The results of the tests can give reference to the simulation and also be helpful to the deeply study of UHV VFTO.The results reveal the characteristics of its distribution to provide reference frame to the simulation and obtain the level of VFTO to provide technical support to the safety of operation.