Study On Immunity Testing Of Unbalanced Traction Current And Processing Platform For Railway Signal Equipment

Railway signal equipment is easy to be disturbed in the railway system, especially in the electrified traction section, the traction current is very easy to form a strong interference to the ground and the cab signal equipment. With the rapid development of high-speed railway and heavy-loading railway, exist many cases of railway signal equipment disturbed by electrical interference, and most of the electrical interference come from the unbalanced traction current. At present, some domestic standards require railway signal equipment to carry out the immunity testing of unbalanced traction current, but the clear testing method is not provided. Based on the above factors, in this thesis, the research on the platform used for immunity testing of unbalanced traction current and data processing for railway signal equipment is conducted. The main work includes the following several aspects:l.The mechanism of unbalanced traction current interfering with railway signal equipment is firstly analyzed. According to the TB/T3073-2003 about the principle of immunity testing of unbalanced traction current, the schemes of automatic immunity testing which includes fundamental pulse and harmonic current testing for track circuit, cab signal and impedance match transfonner equipment based on virtual instrument are formulated. For the realization of automatic testing, the scheme of automatic generation of harmonic interference and frequency shift signal as well as closed loop adjustment is designed.2.According to the scheme of automatic immunity testing, the hardware and software of virtual instrument platform is designed. The hardware includes the test part and auxiliary part. The software includes the design of fundamental pulse and harmonic current test, signal generation, transient interference processing and harmonic analysis; For the transient interference, the principle of the wavelet transform and choice of wavelet decomposition scale and wavelet function in dealing with the transient interference is analyzed. For the harmonic analysis, the traditional FFT may bring errors due to spectrum leakage or other reasons; To solve this problem, the windowed interpolation FFT algorithm is analyzed and applied into the automatic harmonic analysis.3.By using the software development platform of LabVIEW, the software of automatic immunity testing and data processing platform is developed and the realization of every function module is introduced. The signal generation module includes harmonic interference and frequency shift signal which is generated by the software, through the AO channel of data acquisition card to the power amplifier. After power amplification, harmonic interference and frequency shift signal are injected to the system under testing together, and through real-time data acquisition and PID control, a closed-loop regulation is achieved; The state of the tested equipment is converted to high and low level by the interface circuit and obtained by the DIO of data acquisition card; During the real-time test, data can be automatically stored; By using the off-line analysis module, the data stored in the test or the data meeting the format requirements may has a variety of analysis, such as time and frequency domain analysis, harmonic analysis, transient interference analysis, etc.4.The measurement uncertainty of the virtual instrument is evaluated by GUM method; Following an evaluation,the accuracy of the platform meets the design requirements. By using this platform, the unbalanced traction current immunity testing for a set of track circuit equipment is carried out, which proves the function and efficiency of the testing platform. The data from the railway site is processed and the influence of the transient interference on the signal and the harmonic characteristics of the signal which contains the interference is analyzed.