| The electrical parameters of the return system and the devices of the return system are the main factors that affect the rail potential.The electrical parameters of the return system,which play a key role in the prevention of rail potential and stray current,are the track-toearth resistance,so it is necessary to improve the measurement accuracy of the track-to-earth resistance.Moreover,due to the continuity of the rail transit power supply system,the cross current in the line adversely affects the rail potential and stray current.For the situation where the rail potential at the terminal is generally high,it is also very important to study the impact of the reflux system devices on the rail potential.In the actual operation line,due to the structural steel bar line track-to-earth resistance measurement,it is susceptible to interference from the grounding of the over rail potential device and the reverse conduction of the unidirectional conduction device.In this paper,by establishing a two-layer resistance network model of the rail-drainage network,the current and voltage distributions of the track under two-terminal grounding and two-terminal ungrounding are analyzed and calculated during the track-to-earth resistance measurement,and the error of the track-to-earth resistance measurement is analyzed.On this basis,the calculation method for the average potential of the track-to-earth resistance measurement using an approximate linear integral average is proposed.Within the measuring length of4.0km required by the specification,under different line conditions,when the average potential is calculated using the arithmetic average,the track-to-earth resistance value is small;and when the average potential is calculated using the approximate linear integral average value,the track-to-earth resistance value is large,but When the approximate straight line integral average value is used for calculation,the measurement error of the track-to-earth resistance is too small.Then the CDEGS simulation model was used to verify the correctness of the conclusion under different measurement conditions.Finally,the actual resistance analysis of the track-to-earth resistance of the existing line and the new line was carried out,and the correctness of the conclusion was also verified.The measurement of the track-to-earth resistance of the unstructured reinforced line section is mainly affected by the location of the rail-to-ground voltage measurement point.In this paper,the rail-to-earth resistance network structure is established,and the rail voltage and current distribution are analytically calculated.The main line does not affect the measurement of the track-to-earth resistance of the unstructured steel bar.When the rail-ground voltage measurement point is selected near the midpoint of the measurement section,the measurement error of the track-to-earth resistance can be effectively reduced.,The choice of measurement location is particularly important.When the true track-to-earth resistance is greater than 4.50Ω?km,the measurement error caused by the analytical calculation of different measurement points does not exceed 0.024??km,and the error is extremely small.Finally,taking the abnormality of the rail potential of Chengdu Line 1 as an example,through the actual measurement and analysis of the feeder currents of the Huafudadao station,Guangdu station and Wugensong station of Line 1 and the current of the unidirectional conduction device in the throat area,it is found that the line contains a large number of crossing currents within the operating time,The ratio of excluding the ride-through current is only0.901%.The long-distance power supply that may appear in this part of the current is one of the reasons for the rise in rail potential.At the same time,the measured data shows that the unidirectional conduction device is almost in the "turn on " state,and the reverse conduction of the unidirectional conduction device is also one of the reasons for the potential rise of the main line rail. |
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