Analysis of Ferromagnetic Resonance in 550 kV GIS Electromagnetic Voltage Transformer

Abstract

Over-voltage caused by many reasons in the power system, where the voltage transformer ferromagnetic resonant over-voltage occur frequently, has great harmfulness. Based on the complexity of the ferromagnetic resonance phenomenon, this paper started from a 550 kV gas insulated metal-closed switchgear (GIS) project, and established a distributed parameter model of ferromagnetic resonance calculation. 12 typical ferromagnetic resonance conditions are selected, and calculated from the simulation software of ferromagnetic resonance. According to the result of the regularity occurrence of ferromagnetic resonance, this paper proposed preventive countermeasures that minimize harm. The calculation result shows that the resonant over-voltage with higher amplitude appears in the case of two circuit breakers running side-by-side or three circuit breakers running side-by-side, with a maximum of about 1.34p.u. and a primary frequency of 1/3 frequency division. The input voltage transformer secondary side detuning device accelerates the attenuation of primary voltage low-frequency oscillation to a certain extent. At the same time, a high amplitude excitation current is produced, the maximum is about 0.986A, and the continuous oscillatory excitation current will cause the VT to burn out in operation.