Optimum Design Of 27.5kV Resistance Voltage Dividing Electronic Voltage Transformer

27.5kV voltage transformer is an important equipment used to measure the voltage parameters of traction network.It is generally installed in traction substation,AT station and section post.Its accuracy and reliability are closely related to the safety,reliability and economic operation of trains.Although the measurement results of the electromagnetic voltage transformer can meet the requirements,there are many faults and even explosions when they are serious.This accident occurs in Jinan power supply section and Shenyang power supply section in China.In addition,the shortcomings of large volume,easy saturation,small linear range,low integration,and the output signal can not be directly used by the computer limit its application and development.At the same time,with the birth of the research on electronic voltage transformer,the above problems can be better improved.However,previous studies are mostly focused on the transformer itself or a single function module.This paper designed the whole system of 27.5 kV resistance voltage divider electronic voltage transformer,and optimized the resistance voltage divider,signal processing circuit and other modules.Firstly,this paper designs the whole system of the new voltage transformer,which includes three modules:resistance divider,signal processing circuit(impedance matching circuit,photoelectric isolation circuit,signal acquisition and output module),merging unit,and designs the selection,process and integration of the above three functional modules separately;secondly,resistance divider and impedance matching circuit has been optimized,including the selection of types and parameters of divider resistors,the determination of optimum structure and size of shielding cover of the resistor divider,the improvement of insulation and packaging mode of divider and the improvement of the function of impedance matching circuit.The optimized resistor divider can better resist the error factors such as resistance characteristics,temperature characteristics and stray capacitance.The interference and measurement error are reduced.And the optimized impedance matching circuit can realize the main functions of filtering,phase shifting and amplitude modulation of the secondary output signal of the transformer according to the error requirements,which further improves the measurement accuracy of the new voltage transformer.Finally,theoretical calculation and simulation verification are carried out for the key parts of the above two optimization design modules.The calculation and simulation results prove the feasibility of the overall system design of 27.5 kV resistance voltage divider electronic voltage transformer.At the same time,the correctness and rationality of the optimization design of the resistance voltage divider and impedance matching circuit are verified.