Research On On-line Monitoring Of Transient Overvoltage For High-speed Emu And Its Waveform Characteristics

With the rapid development of high-speed railway at home and abroad,more and more attention has been paid to the safe and reliable operation of Electric Multiple Units(EMU).Studies have shown that the overvoltage generated during the operation of the EMU is one of the important factors affecting the operation safety of the EMU.The internal and external overvoltage generated in the actual operation of the EMU will accelerate the insulation aging and even insulation breakdown of the high-voltage components on the roof,and the overvoltage coupled to the vehicle body will also have a serious impact on the normal operation of the on-board electronic equipment.In order to analyze the causes of overvoltage faults and the impact of overvoltage on EMU,it is particularly important to monitor and analyze the transient overvoltage phenomenon of EMU.This paper focuses on the online monitoring technology of high-speed EMU transient overvoltage and the analysis of the measured overvoltage characteristics,including the mechanism of overvoltage,the characteristics of overvoltage,the design and development of monitoring system,and the analysis of overvoltage data.The research results are of great significance in the on-line monitoring of transient overvoltage of EMU,the intelligent identification of overvoltages and the networked construction of EMU in the future.The paper firstly sorts out the types and generation mechanisms of the internal and external overvoltage of the EMU,and analyzes in detail the technical requirements,monitoring principles,characteristics and the theory of the overvoltage characteristic analysis method of the overvoltage on-line monitoring system.These works provide a theoretical basis for the design and development of the overvoltage on-line monitoring system and the overvoltage data analysis.On this basis,according to the characteristics of the EMU monitoring environment and the system technical indicators and functional requirements,the software and hardware design scheme of the EMU transient overvoltage on-line monitoring system is given,and the over-voltage on-line monitoring system is designed and developed by the combination of the host computer software and the system hardware.The system carries out program development and algorithm design from two aspects of power quality monitoring and overvoltage monitoring,and effectively realizes the visual monitoring of data.The reliability and integrity of data acquisition are verified and guaranteed through surge shock test and vehicle test,which provides data support for subsequent data analysis.Finally,using the self-developed overvoltage online monitoring system to measure the overvoltage data,the S-transform analysis method is used to analyze the over-voltage in the time-frequency domain,and the effective feature quantities are extracted and statistically analyzed according to the S-transform results.Combined with characteristic quantities,a preliminary identification and analysis scheme of overvoltage types is given.The research results show that the extracted feature quantities can effectively and accurately represent the characteristic information of various types of overvoltage,which provides theoretical basis and data support for the research on overvoltage identification and classification of EMU.