Study On The Mechanism Of Simulation And Expert System Of Voltage Transformer Fuse Impulse Current

In ungrounded system, potential transformer is usually installed in the substation bus, which is used to monitor the bus voltage to the ground. The high voltage side of potential transformer are connected to ground directly. In the system of the single-phase grounding or arc grounding, due to the nonlinearity of the potential transformer excitation winding and the matching of the capacitance parameters of the system, occurring the phenomenon of over current, resulting in PT high-voltage fuses, and even cause PT burning phenomenon, cause power outages, seriously affect the operation of the power system reliability and stability. In addition, lightning strikes a tower or a lightning strike will also bring serious impact on the normal operation of the PT. In order to rapid analysis of substation busbar voltage transformer fuse, this article mainly carries on the following several aspects of research and design.This paper introduces the research status of piezoelectric fuse causes and corresponding expert system at home and abroad. Then, the mechanism and classification of ferromagnetic resonance are analyzed, and the influence of the ferromagnetic resonance on the system PT is analyzed. At the same time, this paper also introduced the harm of the low frequency oscillation of the nonlinear condition and power line and the influence of different lightning effect on power grid.The simulation model of IEEE37 node is built based on ATP-EMTP, which is used to simulation of single phase grounding, arc grounding, different periods of circuit breaker closing to the cause of the effect of ferromagnetic Xie Zhen low-frequency nonlinear oscillation and the effect degree of current on the primary side of the fuse PT caused. This paper also analysised the influence of lightning rod tower and lightning shielding failure line on PT fuse.An expert system that used to diagnosis the fault of the fuse is designed. The expert system can diagnosis the ferromagnetic resonance, low frequency oscillation and lightning current when the fuse is fused, and can be specific to what kind of factors caused by over current. We designed a variable pressure fuse simulation software by Matlab, which is used to emulate state of current when ferromagnetic resonance or low-frequency nonlinear oscillation happened.