Abstract
For a 550kV HGIS electromagnetic voltage transformer(PT), ferromagnetic resonance occured after the disconnector was opened. In this paper, firstly, considering the ferromagnetic resonance condition, the fault disintegration, fault recording, and operating overvoltage datas were analyzed to analyze the causes of ferromagnetic resonance.Then a HGIS simulation model was built by EMTP-ATP to calculate very fast transient voltage which was caused by opening operation of disconnector. According to the results, the VFTO amplitude at the PT is not large, but the wave front steepness reaches 2837kV/ μs, which is harmful to the inter-turn insulation of the PT primary winding. It may cause partial inter-turn short circuit and then induce core saturation. Finally, the preventive measures of ferromagnetic resonance are proposed.
I. INTRODUCTION
In recent years, with the rapid development of power grids, HGIS (GIS) has been widely adopted by many substations and power plants because of its safety, stability, high integration and small footprint [1-3]. Voltage transformers are an important part of HGIS (GIS), and basically use electromagnetic structure, as voltage, energy measurement and relay protection [4-6].
VI. CONCLUSION
The VFTO occurred during the opening operation of the disconnector, and the electromagnetic voltage transformer structurewas weak tolerant to the Very Fast Transient Steep Wave .The wave front was too steep, which was easy to damage the primary winding insulation.
After the primary winding being partially short-circuited, the iron core was extremely saturated, which will result in ferromagnetic resonance. The primary winding would be burnt due to the overload of the ferromagnetic resonance wire.
It is recommended to optimize the relevant operation mode and sequence to avoid the opening operation of the HGIS disconnector to generate VFTO after the voltage division between equivalent capacitance of the ground and the capacitor of the fracture.
HGIS (GIS) compression should be designed with a better structure to meet the safe operation of the grid.
