Study On Location Of Grounding Fault With Interruption Of All-Parallel At Power Supply System

As the speed and passenger volume of high-speed railways continue to increase,the power requirements for traction power supply systems are also increasing.Chinese high-speed railway passenger dedicated lines generally adopt all-parallel AT(Auto-transformer)power supply mode,which has the characteristics of complex structure and high failure rate compared with other modes.In the failures of the traction network,short circuit faults account for the majority of the faults,and the probability of disconnection faults with interruption is relatively small.Therefore,most of the studies on traction network fault location at this stage are related to short circuit faults.When a disconnection fault occurs in the all-parallel AT power supply traction network,it usually appears accompanied by a high transition impedance,and it may cause the feeder protection to fail and cause the fault to exist for a long time,causing serious consequences.Therefore,the research on location of disconnection faults is also very necessary.Firstly,according to the actual power supply situation of high-speed railway traction power supply system,this paper divides the all-parallel AT power supply traction network into two sections including the traction substation to the AT and the AT to the subarea.The currents are respectively studied in detail in the short-circuit fault and grounding fault with interruption in these two sections and find out the relationship between short-circuit current and current at the exit of the traction substation,AT and subzone.Secondly,by comparing and analyzing the current distribution under short-circuit and grounding faults with interruption,the identification method between short-circuit fault and grounding faults with interruption and different types of grounding faults with interruption is found out,and all-parallel AT is built by Matlab/Simulink.Fault simulation model of the power supply traction network,through the simulation data obtained by the simulation,verified the correctness of the identification method.Finally,according to the current characteristics of different types of grounding faults with interruption in the different all-parallel AT power supply traction networks,three kinds of fault location formulae for fault location are deduced,and then simulation verification is performed for each ranging method.The advantages,disadvantages and applicability of each method were found out.Finally,considering the short circuit fault and grounding faults with interruption of the traction network,a fault location scheme for the all-parallel AT power supply traction network was designed.