Estimation of VFTO caused by same frequency and phase withstand voltage test of GIS

摘要

The same frequency and phase withstand voltage test of GIS has been applied in the transition test of substation expansion. However, when the breakdown accident occurs in the test process, the VFTO will seriously threaten the safety of the tested equipment and operating equipment. Aiming at a same frequency and phase withstand voltage test of GIS, EMTP simulation model is established and the parameters are determined. The VFTO that may occur in the GIS under different operation modes and different test conditions are studied. The restraint effect of the test protection resistance on the VFTO is analyzed, and the corresponding measures for safety are given. The results demonstrate that different operation modes of the tested GIS system will produce different VFTO. When the single breakdown is changed to ground flashover, the over-voltage amplitude of the non-tested bus node will increase, and the over-current of the break will also increase. The conventional test protection resistance cannot restrain the VFTO. The test state sensing measures and other safety measures need to be implemented in the test.