Protection Device Development Of Traction Transformer And The Theory Study

Traction transformer is critical to traction power supply system. Its security and stability directly affects the normal operation of electric railway system. With the rapid development of high-speed electrified railway, more powerful and better performance automatic device is urgently needed. So it is important to develop the protection equipments suitable for our country's electric railway. The main task is to develop the electric railway traction transformer protection devices and the related simulation as well as the associated theory research.First of all, the paper summarizes the structure, power supply type and electrical characteristics of traction power supply system. This paper studies the transformer differential protection theories and mainly focuses on the impedance matching balance transformer differential protection principle and the detailed derivation of differential current.Secondly, the paper analyzes the principle and configuration of the traction transformer's main protection and backup protection, and realizes the protection functions in the new digital platform. Also, the communication function with the MODBUS protocol and IEC60870-5-103 protocol has been realized through the 485 serial port and Ethernet.Then, taking the differential primary protection of impedance matching balance transformer as an example, this paper builds the fault simulation platform with MATLAB-simulink tools on which simulates the action situation of differential protection under the operating mode of normal, external and internal fault. As well as verified the correctness of the protection principle, it also provides a new validation idea for the development of protection devices.Finally, the paper proposed a negative sequence loss ratio diagnosis theory of transformer inter-turn fault based on three-phase two-winding transformer. In addition to the application of the wireless sensor network, a new method is proposed for the protection of transformer inter-turn fault. This method also applies to electric traction transformer.