Fault Monitoring Of On-board Voltage Transformer Of High-speed EMU

Vehicle voltage transformer is an indispensable high-voltage electrical equipment on high-speed EMU,which has the functions of catenary voltage measurement,power measurement and measurement protection.In recent three years,according to the operation statistics of multiple EMUs in Beijing,Shenyang and other bullet train sections,the explosion and other failures of on-board voltage transformer in the previous five years accounted for a large proportion,which resulted in the burnout of the core of the voltage transformer,the tripping of the power supply station in serious cases,and the running accidents such as train stoppage.Through the following horizontal and vertical comparison,it is concluded that vehicle voltage transformer is more vulnerable to over-voltage impact.Firstly,compared with the power grid seldom suffered from the impact of operating over-voltage,the operating over-voltage caused by frequent over phase and start and stop of EMU has a great impact on the vehicle voltage transformer.Second,compared with the previous Shaoshan series locomotives which used compressed air switch,the current EMU adopts vacuum circuit breaker,which has faster speed,larger current change rate and larger operating overvoltage amplitude caused by vacuum circuit breaker in the excessive phase.The research shows that the main reason for the failure of on-board voltage transformer is that the EMU frequently suffers from the impact of excessive phase overvoltage.Therefore,the research and development of on-line fault monitoring device of high-speed EMU on-board voltage transformer,on-line monitoring and early warning display of the operating voltage transformer,provides qualitative analysis basis for judging its reliability,improves the stability and economy of the traction power supply system,and is of great significance for reducing the fault and ensuring the safety of railway transportation.Firstly,this thesis models the on-line fault monitoring device of vehicle voltage transformer.The common way to monitor the voltage transformer is to monitor the secondary side voltage of the voltage transformer.However,when the failure of voltage transformer leads to core saturation,the secondary side voltage may be distorted and there is nonlinear distortion,so the secondary side voltage monitoring may be biased.Therefore,the physical monitoring model of the voltage transformer designed in this thesis is to take a small part of the coil on the primary side winding as a tap voltage.The tap voltage of the primary side and the primary side voltage always have a linear relationship,so the monitoring of the voltage transformer can be realized by monitoring the tap voltage of the primary side.Then,through the over-voltage generated by the over-phase of EMU,the physical monitoring model of voltage transformer is analyzed and calculated theoretically.Combined with Matlab / Simulink,the simulation model of the whole traction power supply system and vehicle voltage transformer is built for the over-phase of EMU.Through the simulation analysis,the accuracy and rationality of the physical monitoring model of vehicle voltage transformer are verified.Finally,a set of on-line fault monitoring device of vehicle voltage transformer based on DSP controller is designed.Determine the overall structure of the hardware system of the monitoring device,select TMS320F28335 as the control core of the system,and expand a series of functional circuits.The hardware system of the fault monitoring device includes power module,reset circuit,clock circuit,external storage of the system,signal acquisition circuit,DSP and a / D interface circuit and other auxiliary circuits.In addition,we use ccs5.5 of Ti and visual studio 2017 development environment of Microsoft to design the software of lower computer and upper computer,complete the design of main program,interrupt program,monitoring signal display program,fault monitoring and early warning program,serial port data communication program,and finally realize the functions of fault monitoring and fault early warning.