Study On Measuring Method Of JTC Ballast Resistance Based On Track Surface Current

Ballast resistance as an important parameter of the track circuit,the value of the deterioration will shorten the effective transmission distance of the track signal,and then affect the normal work of the track circuit and the locomotive signal,to bring safety risks to the train operation.Therefore,it is required that the site staff can timely understand the change of the value of ballast resistance,and take necessary maintenance measures as appropriate to ensure the normal and stable work of the track circuit.With the development of the railway,jointless track circuit has been widely used in our country,and because of the track circuit on the line with compensation capacitor and tuning unit equipment,so that the original ballast resistance measurement method is no longer applicable.Therefore,it is urgent to study a high-performance ballast resistance measurement method which is not affected by the fault of compensating capacitor and tuning unit and other rail surface equipment.Based on the above requirements,the main research work of this dissertation is as follows:(1)Based on the transmission line theory,the mathematical model of the current amplitude envelope of the jointless track circuit in the adjusted state is established and verified,and the influencing factors are analyzed.Based on the basic theory of transmission line and according to the structure,working principle and signal transmission characteristics of jointless track circuit,the current amplitude envelope of jointless track circuit in adjusted state is simulated and modeled.Based on this model,the influence law of ballast resistance,compensation capacitor and equipment faults in the tuning area of receiver and sender on the rail surface current amplitude envelope is analyzed respectively.(2)Based on the regression analysis and Akichi information criterion AIC,the formula of ballast resistance estimation based on the current amplitude of track surface signal and "three-point fitting method" is proposed,and the corresponding measurement method suitable for railway site is designed.Based on the analysis results of the above influence law,the least square method was used to carry out exponential fitting for the rail surface current amplitude envelope,and the regression calculation formula between the attenuation factor in the fitting parameters and the ballast resistance was constructed by using Akachi information content criterion AIC.Furthermore,based on this formula,a field measurement method of ballast resistance is proposed based on the measured values of the rail surface current amplitude at the receiving end of the rail surface and the compensation capacitance C1 and C2."Three-point fitting method" refers to the use of measured rail surface current amplitude three points,the method of fitting solution of ballast resistance.The function and performance of the proposed method were verified by the hardware-in-the-loop simulation platform of the State Key Laboratory.Experimental results show that the proposed method is robust and accurate without compensating capacitance fault,receiver tuning fault and transmitter tuning fault.(3)Based on the measurement method research in this paper,the measurement software of ballast resistance is designed and realized.According to the previous theoretical method research,this paper comprehensively analyzes the demand of track circuit ballast resistance measurement software,and gives the overall design structure process of the software,the design of the interface and function of the software,and the verification of each functional module.There are39 pictures,9 tables and 73 references.