| The track-train continuous information transmission system plays an important role in Chinese Train Control System(CTCS),which consists of ZPW-2000A type Jointless Track Circuit(JTC)and Track Circuit Reader(TCR).It aims to realize the continuous transmission of the corresponding train control information from ground to train using the track circuit signal,so as to ensure the safety and reliability of CTCS for the control of train operation.A phenomenon is observed in the field experiments of high-speed railway that the deviation of carrier frequency of received signal in TCR will increase with the increase of train speed Although some relevant theoretical studies have been carried out and the formulas for calculating the deviation of carrier frequency have been given,it is still unclear about the maximum value of the deviation of carrier frequency for a specific JTC and its corresponding conditions.It's also necessary to know whether this deviation value will adversely affect the demodulation process of TCR.Therefore,it is of great practical significance and research value to study the above problems.The main contents of this paper are as follows:1.Based on the theory of even transmission line,the influence factors of carrier frequency deviation of received signal in TCR are analyzed,and the maximum deviation values of different JTCs are solved in their normal conditions.The transmission characteristics equivalent model of compensation unit in JTC is established and the influence law of the carrier frequency deviation is determined by analyzing this model with JTC in normal conditions.The analysis results show that the deviation is directly proportional to the rail impedance,ballast resistance,carrier frequency and capacitance of compensation capacitors,while it is inversely proportional to the length of compensation unit.The maximum value of this deviation is calculated based on the above influence rules.2.The maximum carrier frequency deviation value of TCR received signal is solved in JTC fault conditions based on Genetic Algorithm(GA),and its effect on the work of TCR is verified by experiments.The theoretical analysis proves that the maximum deviation will be further increased with the fault of compensation capacitors.Considering the complexity of fault combinations of compensation capacitors,GA is adopted to solve the maximum deviation when compensation capacitors are in fault conditions.In the simulation of the genetic evolution process,the values of all compensation capacitors are taken as the gene of genetic individuals,and the deviation is taken as fitness,with the corresponding constraints are formulated according to the actual situation.The adaptability of TCR to this maximum deviation is experimented which indicates that TCR has a large allowance range for the carrier frequency deviation,and the maximum deviation will not have a negative impact on TCR in current conditions.3.Based on TCR remote monitoring system,the monitoring software for the carrier frequency deviation of TCR received signal is designed and realized.The monitoring software for the carrier frequency deviation is designed based on the TCR remote monitoring system.In consideration of the state of compensation capacitors and the practical application scenario,off-line analysis mode and on-line monitoring mode are designed in this software.The experiment shows that the software designed in this paper can effectively realize monitoring for the deviation of carrier frequency.At the same time,the monitored carrier frequency deviation can guide the setting of carrier frequency search range when TCR host demodulates the sampled signal.The amount of figures is 39,the amount of tables is 7,the amount of references is 59. |
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