Study On The Dynamics Of Pantograph-catenary Arc And The Erosive Effect Of Pantograph-catenary Arc On The Pantograph And Catenary

The pantograph-catenary(PC)system plays a key role in the electric energy acquisition for high-speed train.Status of pantograph-catenary systems is critically important for working security and reliability.At present,the relationship between pantograph and catenary has become one of three crucial relationships for high-speed railway.Multiple factors will result in PC arc,such as the operation of pantograph rising and lowering,locomotive body vibration,track irregularity,ice coating on the contact line in the cold environment,etc.On the one hand,electrical electromagnetic harmonic and overvoltage due to the arc ignition and extinguishment will throw great potential threaten on the electrical equipment and the secure operation of train.On the other hand,the intensive heat released from arc will induce severe damage on both pantograph strip and overhead contact line material,resulting in an obvious decrease of work life.Therefore,it is necessary to do researches on the characteristics of pantograph-catenary arc.Because of the high risks as well as great difficulties in field experimental measurements,early studies on the pantograph-catenary arc were mainly accomplished by laboratory simulation experiments.Those experiments are helpful for comprehending the basic electrical parameters during the processes of arc ignition,evolution and extinguishment.Because of the transient variation and relative randomness of arc plasma,as well as the complicated factors that influence the properties of arc plasmas,it is hard to obtain the details of the arc plasmas themselves,with regard to the space-time evolution of internal parameters,and the erosive effect of it on electrodes.Therefore,the numerical simulation was used to study the dynamics of PC arc during pantograph lowering process and the erosive effect of PC arc on the materials of PC system.This paper focused on the dynamic characteristics of pantograph-catenary arc during the pantograph lowering process.A dynamic pantograph-catenary arc model was established based on the classical magneto-hydrodynamics(MHD)theory,with the temporal evolution of PC arc dynamics taken into account.And the dynamic mesh technique was utilized to take care of the departure process between the pantograph and catenary.The model was calculated by a modified commercial fluid code Fluent.The temperature and flow fields during pantograph lowering were calculated.The evolutions of shapes and temperature distributions of PC arc were analyzed.The interactions between temperature fields and flow fields were elaborated.The effects of pantograph lowering speed and input current were studied.The emission spectrum of PC arc plasma was measured based on the PC arc test device.The Boltzman method was used to caculated the average temperature of arc plasma.The result from simulation was compared with that from experiments in order to validate the model.Based on the magneto-hydrodynamics(MHD)theories and the heat conduction theories from arc to electrodes,a model of coupled pantograph-catenary arc and electrodes was established.The melting and solidification model was added to the energy conservation equation to calculate the melting process of electrodes under the effect of arc.The distributions of heat flux on the pantograph and catenary surface were calculated.The temperature distributions and the depth of melting pool,as well as the radius of melting pool on the pantograph and catenary over time were simulated.The effect of current on the size of melting pool was analyzed.The experiments about the erosive effect of PC arc on the pantograph was carried out to validate the model.