Transient Simulation And Analysis Of Impendence-matched Balancing Transformer

High-speed railway is the key developing direction of electrified railway of our country. Traction transformer is a critical equipment of power supply system. In order to adapt the new construction and development of electrified railway, the three-phase to two-phase impendence-matched balancing transformer (IBT) with neutral point to earth, is widely used, but mistaken operations often occur. Whether the protective performance can be improved depends on the extent to which people understand the features during magnetic inrush and inner faults. It is necessary to study the transformer's voltage and current characteristic under transient conductions, relaying protection and so on.The transient simulation of transformer such as inrush current, inner faults is required to study protection method and improve performance. The connection of IBT and inner impendence-matching are studied, and the transient model for IBT is designed based on analyzing electromagnetic coupling of multiwinding transformer. Inrush current, external short and inner faults are simulated and analyzed. The comparison of simulation results and known research findings prove the model is correct.Due to the instinct disadvantages of differential protection for transformer, it's an effective approach to enhance the reliability of transformer protection relay that the voltage is introduced. The protective principle based on transformer model is one direction for future research. The voltage-balanced equations are proposed based on transformer model of normal operation, and whether the equations are tenable decide protective operations. The voltage-balanced equations are proposed for IBT. Based on the voltage-balanced equations, a novel protective principle based on the transformer model, its operation characteristic and operation equation are proposed. The setting rules and formula are obtained, and the simulation test is carried out. The simulation results prove that above protective principle, operation characteristic and operation equation are correct.