Research On High Resistance Grounding Protection Scheme Of Railway Traction System Based On "Train-station-ground" Integrated Synchronous Monitoring System

When high resistance grounding fault occurs in the traction power system of high-speed railway,the fault current is weak and the measured impedance is not enough to cause impedance relay action.And the current increment protection adopts the quantitative analysis method by setting the starting value of current sudden change,which cannot effectively guarantee the sensitivity and leads to low positive rate.To address the problems above,by analyzing the electrical characteristics of high resistance grounding fault of traction power system and designing the wide area backup protection scheme based on the synchronous monitoring of EMU and traction station,a high resistance grounding protection scheme of traction power system with auxiliary information of energy consumption and power quality monitoring data is detailly studied in this paper.,The main research work of this project is as follows.Firstly,the high resistance grounding fault simulation model of traction power system is built in MATLAB / Simulink platform,where electrical characteristics of traction network with different transition resistance and different fault location are compared and analyzed.The simulation results show that the short-circuit fault will lead to the feeder current mutation and voltage sag,and that with the increase of the grounding transition resistance,the current mutation of the traction network after the fault will gradually go close to the locomotive load current,making it difficult to effectively identify the fault by detecting the electrical signal at the protection installation.Based on the trip record of current increment protection and the measured current waveform of locomotive passing through split phase,it is verified that EMU may still cause misjudgment of current increment protection,and extra electrical information is needed to achieve accurate identification of high resistance grounding fault.Then,the integrated synchronous monitoring model of "train-station-ground" for highspeed railway traction power supply is proposed with the monitoring data of energy consumption and power quality of EMU and traction station.In the model,the hardware structure and implementation functions of on-board monitoring unit,ground monitoring unit,data center and communication network are introduced,the key factors affecting train energy consumption are analyzed and the traction station is evaluated whether the power quality monitoring data of PCC point of power station is in line with the national standard.By using adjacency matrix to develop the dynamic topology reconstruction method,the problem of train-station cooperation is solved,and the effects of different protection structures and communication schemes on the performance of wide area backup protection are compared and analyzed.Multiple Wan test results demonstrated that the real-time performance and reliability of wide area backup protection can meet the performance requirements of wide area backup protection.Combined with the actual monitoring data,the Kalman filter algorithm is used to optimize the processing of bad data,which improves the accuracy of wide area monitoring data,and verifies that the "train-station-ground" integrated synchronous monitoring system can provide effective and reliable auxiliary information for the identification of high resistance grounding fault in traction power system.Finally,based on the synchronous monitoring data of EMU and traction station,a multiinformation wide area backup protection scheme is proposed to analyze the active power difference between traction station and EMU under fault and load conditions.The results show that the continuous active power loss caused by transition resistance is much greater than the line loss under normal conditions.The fault detection method characterized by the difference of active power is formed.By studying the cooperation mode of multi-point wide area monitoring data and existing protection,an independent wide area backup protection scheme is proposed by using the difference of active power between at substation and EMU,so as to realize line selective tripping and improve sensitivity.The cooperation of wide area monitoring data and current increment protection is used as auxiliary electrical information to improve the reliability of current increment protection.The judgment effect in typical scenarios and the fault detection performance under wide area information interference are compared and analyzed.In order to ensure reliable and effective fault identification,it is necessary to synchronize the monitoring data of different measuring points,configure PT secondary disconnection locking function and detect the unipolar value of abnormal data.