Analysis and Study of Excitation Inrush Current Characteritics of High-Impedance Power Transformer

With the development of economy and society, the problems of decreasing system impedance and serious excessive short-circuit current have generally occurred in the backbone network of large power grid interconnection and the urban power grid with large load concentration. The cost of circuit breakers will rise sharply with the growth of the demand for breaking capacity. In order to limit the short-circuit current on the low-voltage side of the transformer, the application rate of high-impedance transformers with low cost, small additional floor space and strong ability to limit the short-circuit current of the system is increasing. The high impedance transformer can increase the short circuit impedance to reduce the short circuit current without increasing the primary device, and has been widely used. This paper first introduces the definition and design principle of high-impedance transformer, and summarizes the realization methods of different high-impedance transformers; Secondly, the inrush current characteristics of the most widely used high-voltage built-in high-impedance transformer are analyzed, and the transformer model is established by Maxwell finite element simulation software. Finally, the inrush current of the high-voltage built-in high-impedance transformer is theoretically analyzed and summarized.