The Simulation And Analysis Of Transformer's Overexcitation

In recent years, with the development of power industry, a large number of large-capacity and high-voltage transformers have been put into use, these transformers (including imports and domestically produced)have been designed in a lower cushion.in this instance,the transformer is sensitive for the voltage fluctuation. It is prone to over-excitation fault. Simultaneity, the development of the high-voltage direct current transmission lines makes the DC transformer magnetic bias increasingly become a common phenomenon.This paper describes the causes and results of transformer's over-excitation, analyze the resolvent at the present time. Summed up the impact of transformer's Overexcitation. Taking the specialized electromagnetism transient software PSCAD/EMTDC to study the factors influencing the Overexcitation of transformer, this model has higher precision, this paper also utilizes MATLAB software to deal with analyzing to the emulation data, which was compared and analyzed with the data of measurement.The simulation results summed up: the relationship of transformer load current and exciting current is impact by the connection mode.the voltage level and the flux density is the main factor of the Overexcitation for transformer, the power grid with capacitive impedance may case flux waveform distortion. The transformer with different structure have different harmonic at the Overexcitation; DC magnetic bias have influence for the Overecxcitation of transformer , and DC magnetic bias may lead to overexcitation protection to the malfunction.