Research On Lightning Protection Of Traction Power Supply Overhead Contact Line In High-speed Railway

Viaduct is widely used in Chinese high-speed railway,so the height of the overhead contact line wires is close to or even greater than that of 110kV overhead transmission lines which causes an enhancement of lightning interception capability.However,the insulation level of the overhead contact line approaches that of 35kV overhead line and no specific lightning protection methods were adopted,which leads to a poor lightning performance of the overhead contact line in Chinese high-speed railway.The operating experience indicates that the lighting trip-out rate of the overhead contact line is up to dozens of times per 100 kilometers per year,which is approximately five times of that for ordinary electrical railway and two orders of magnitude higher than that of 110kV overhead transmission lines.The security of high-speed railway is significantly threatened by the extremely high lighting trip-out rate,so improving the lightning protection capability of the overhead contact line is an outstanding problem should be solved.Nevertheless,the off-the-shelf technology can’t satisfy the lightning protection of high-speed railway,so simulation method of lightning overvoltage,lightning protection scheme and device need to be intensive developed.The study works and the main conclusions specific to lightning protection of high-speed railway overhead contact line are as follows:In this thesis,it has studied the modeling method of lightning eletromagnetic transient calculation for high-speed railway viaducts.To simplify the problem,the thought that creating the transient equivalent circuits of piers and box girders firstly and then build a whole model of high-speed railway viaducts is put forward.It has proposed a modeling method of establishing lightning electromagnetic transient model of structural units,which is mainly composed of driving-point function approximation and circuit implementation.This method allows for actual structure in complex reinforcement layout,and it provides higher accuracy without simplifying the steel structure.For the first time,the impulse response test of viaduct pier is launched to verify the effectiveness of this modeling method.From the above,the typical equivalent circuit of high-speed railway viaduct for electromagnetic transient calculation has been established,and it has laid the foundation of an accurate simulation of lightning overvoltage on the overhead contact line.The author has studied the calculation method of lightning induced overvoltage on the overhead contact line with considering the lossy ground,the nonlinear process of arrester operating and insulator flashover.Meanwhile,the simulation program has been established to calculate the lightning induced overvoltage on the overhead contact line,and the effectiveness of the calculation method and program is also validated.In the thesis,the author has established the calculation model of direct lightning overvoltage and lightning induced overvoltage on the overhead contact line,and calculated the lightning flashover rate as well.By analyzing the distribution of lightning overvoltage,the lightning withstand level and the lightning flashover rate of the overhead contact line with different heights and different ground resistivity,the author has gain the characteristics of lightning flashover in the overhead contact line.The average lightning flashover rate reaches to 41.5 per 100km per year(Reduction to 40 thunderstorm days),direct lightning contributes 12 times of indirect lightning.Meanwhile,most of the flashover occurs on the F-line,and the direct lightning flashover rate is mainly influenced by the height of the overhead contact line as the indirect one is influenced by ground resistivity.The lightning protection scheme in the high-speed railway overhead contact line has been studied,and the technical strategy of lightning protection in the overhead contact line has been proposed as follows:Direct lightning protection comes first,balances the indirect lightning;Major protection for the F-line,minor protection for the T-line.According to the result of simulating the overhead contact line model which contains lightning shield wires,arresters,or parallel protection gaps used for protecting insulators,the author proposes the comprehensive lightning protection scheme of the overhead contact line specific to different level of reliability as follow:The measure of setting up lightning shield wire or arresters with series gap beside each insulator on F-line should be taken in preference,and it is appropriate to lift PW-line as lightning shield wire.When it is necessarily prevent insulators from lightning damaging that would lead to permanent fault,additionally,parallel protecting gap should be set up.The protection scheme,lift the PW-line as lightning shield wire and install arresters with series gap beside each insulator on both F-line and T-line,could further decrease the lighting trip-out rate in intensive lightning activity section.The comprehensive protection scheme has been implemented in Beijing-Shanghai and Wuhan-Guangzhou high-speed railway.The critical technology of the arrester with series gap has been studied,and a kind of separate arrester integrated into the insulator with series gap is proposed.This structure can make sure stable dichaging voltage of the gap.At the meantime,a kind of U-shaped installation fitting is also designed to guarantee that the arresters could be securely set up.The author has also developed a method of explosion-proof for the arrester itself.Another study comes up with the key technical parameters of arresters,the test condition and method of lightning impulse test of volt-second characteristic,vibration test and explosion-proof test for technical testing.The arrester samples which have been developed all passthese three testing assessments.The stereotype arresters have already been set up in KunShan South substation on Beijing-Shanghai high-speed railway,and work to good effect.The parallel protective gap for insulator has been as well developed which has a structure in the shape of arietiform,also discharges stably.Another study puts forward the key technical parameters,material of the protective gap,the test condition and method of lightning impulse test of volt-second characteristic,thermal stability test and arc test in power system for technical testing.The developed samples all pass these three testing assessments,and the stereotype parallel protective gap is surely capable to be produced.In conclusion,the main innovations of this thesis are as follows.Firstly,the author has established the model of box girder and pier of high-speed railway viaduct constructed by complicated steel network for lightning electromagnetic transient calculation.The impulse response test of pier has been launched to verify the effectiveness of this modeling method for the first time.The method of calculating lightning induced overvoltage in the overhead contact line is proposed,simultaneously considering the lossy ground,nonlinear process of arrester operating and insulator flashover.The simulating program has also been developed.Secondly,the characteristic of lightning flashover in the overhead contact line is gained.The average lightning flashover rate reaches to 41.5 per 100km per year(Reduction to 40 thunderstorm days),direct lightning contributes 12 times of indirect lightning.Meanwhile,most of the flashover occurs on the F-line.On the basis of reliability,the author proposes the comprehensive lightning protection scheme of setting up lightning shield wires,arresters and parallel protective gaps in the overhead contact line.The scheme has been implemented in Beijing-Shanghai and Wuhan-Guangzhou high-speed railway.Finally,the author proposes a kind of separate arrester integrated into the insulator with series gap.The author has developed a method of explosion-proof for arrester itself.Meanwhile,the author comes up with the simulation experiment of testing long-term vibration fatigue.The stereotype products all have passed the short circuit current test and the 2-million times vibration test.Furthermore,they are set up in KunShan South substation on Beijing-Shanghai high-speed railway,and work to good effect.