| More and more Gas Insulated Substation (GIS) has been put in use in electric power system for their advantage of less area occupancy, steady running and convenient maintaining. But Very Fast Transient Overvoltage (VFTO) is generated during disconnector or circuit breaker operation in GIS.VFTO has the characteristic of the steep front of several nanoseeond to several tens nanosecond, and it is very dangerous to the insulation of GIS equipments. At the same time, parts of the transients also come into the secondary circuits and outside of GIS, and will endanger the safe operation of secondary equipment and longitudinal insulation of the transformer.At present, VFTO is calculated by using EMTP which need operator to study solid knowledge in the theory of overvoltage, which is difficult to the engineer. Therefore, the development of calculation software for VFTO simulation that has friendly interface has great importance.At first, the modeling methods for each primary equipments (elements) in GIS are discussed and summarized in this thesis. The field analysis and parameter calculation for some actual equipments (elements) of GIS are carried out by utilizing finite element software—ANSYS, and make a good foundation for subsequent research. On the basis of the developing platform Microsoft Visual Studio 2008, C# of Microsoft is applied to develop the GIS Transient Program (GISTP) for VFTO simulation based on the Bergeron Method. Simulation model for GIS is established according to electric main wiring diagram of the primary system in the software. Therefore the engineer can use it easily. GISTP passed the provincial functional test for software, the comparision between GISTP and EMTP verifies the accuracy of GISTP. Then, two actual GIS are calculated in different operating modes by using above parameters obtained and GISTP. At last, the protective measures and reasonable proposals for the operation of GIS are provided in accordance with the result of the calculation. |
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