Research on PT Ferromagnetic Resonance Region and the Controllable Damping

In the neutral ungrounded system, potential transformer (PT) ferro-magnetic resonance is a kind of interior overvoltage which is frequently appears and creates most of the accidents. Whether the elimination measures are reasonable and effective or not affects the security and stability of the power system directly. Fundamental research has been done on the resonance region changeable situation and the characteristics of each resonance region under different system parameter and PT saturation characteristics. According to the occurring principle of PT ferromagnetic resonance and the characteristics, a novel effective controllable damping device is designed, which will change the correlative parameter that lead to resonance to make the circuit parameter of the system get out of the resonance area to eliminate the resonance. The accuracy of the fundamental analysis and the effectiveness of the elimination measure have been verified by the digital simulation based on EMTDC/PSCAD and by the high voltage propotype experiment.