| As an important part of railway power system, railway automatic blocking and continuous transmission lines (RABCL) is responsible for the power supply of railway signals and station equipments. Its fault would effect normal railway transportation, even bring great financial loss. Therefore, reliability of RABCL power supply is treated important. However, RABCL could be affected easily by environment, and its fault often happens. In order to manage fault situation and enhance railway operation quality, finding and clearing fault quickly is needed, so fault measurement and location are needed urgently.Based on study of RABCL characteristic and its fault location research actuality, the paper points out the possibility to use traveling wave in RABCL fault location, but there are still some key points which needs more analyzing.On the base of introduction of fault traveling wave fault location theory, a PSCAD/EMTDC model of RABCL is set and its traveling characteristics are analyzed. Theory analysis and simulation results show that RABCL is fit to use double-terminal voltage traveling wave and D fault location principle, and point out the getting traveling wave signal model.GPS time synchronization mode of fault location system based on traveling wave and the cause that GPS second plus turns out of steps are analyzed in fault location system based traveling wave of RABCTL. Then modified arithmetic is given which is used to reduce out-of-steps of plus signals from two terminals when GPS second plus signals are receipted normally. When GPS second plus signals couldn't be receipted normally, GPS second plus signals are replaced by assistant time system consisted of backup clock module to synchronize crystal time signals, in order to realize two terminal time synchronization.In this paper. By means of software PSCAD/EMTDC, an equivalent model for JDZ10-10 type of PT is built and embedded into RABCTL to carry out systemic simulation in which the wavelet modulus maxima is used to detect the voltage traveling wave front at the both sides of PT under the transmission line at fault. It is discovered in the simulation that the JDZ10-10 type of PT commonly used in RABCTL possesses good transfer characteristic in low frequency band from zero to 125 kHz and can accurately transfer the signal and polarity of traveling wave front without time-delay; during the time period of one or two millisecond after fault there is an oscillation in the secondary side of the PT, so that during the transferring process one wave front at the primary side may cause multi wave fronts at the secondary side. Under the condition of accurately recognizing the first wave front at the secondary side, the voltage traveling wave can be adopted in fault location of RABCTL. Simulation results also prove that the traveling wave based fault location principle is adaptable to RABCTL.Finally, In RABCTL, accurate fault location of overhead lines combined with cable is hampered by different wave speed. Based on analysis of traveling wave transmission at hybrid line joints,this paper introduced a double-ended measurement based on time-difference-Sear -ch. The measurement determines fault zone and wave speed by different time when traveling wave reaches line ends, and then gets accurate fault distance. Simulation result shows the introduced method is feasible.Research in this paper could be useful in further study of RABCL fault location equipment, and be significative in both theory and application research. |
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