Research On Fault Location Method Of All-Parallel At Tranction System Based On The Current Of Cpw

With the large-scale construction and being put into operation of high-speed railway, as a power source the reliability of high-speed railway traction power supply system faces severe challenges.The high speed railway traction power supply system adopts all parallel AT power supply mode,this way of power supply has lines in parallel in the AT the place,and will make the line structure more complex. The higher request of the fault location device of traction power supply system and its automation function is put forward, which requires that better selectivity and the higher reliability, faster action speed,and the faster fault recognition, judgment,recovery time.So the analysis and research of high-speed railway traction supply network fault location of all parallel AT power supply mode to find a quick and accurate fault location scheme that suitable for high speed railway fault location,has important significance for the safe and reliable operation of the high-speed railway.In this paper,firstly,according to the characteristics of high-speed railway all parallel AT power supply mode,the fault loop current of T-F short-circuit fault condition whicht is a special case of all parallel AT traction net has been analyzed,on the base of that,the superiority and inferiority of the three traditional ranging scheme:"AT neutral current ratio fault location method"," up/down line current ratio fault location method","paralleling lines current ratio fault location method"are taken some comparative analysis.The system impedance measurement of T-F,F-R,T-R short-circuit fault cases were deduced,under the condition of T-F fault the"AT neutral current ratio fault location method" will no longer applied. Then through the analysis of the conclusion that under the T-F fault condition,the relationship between the measuring impedance of the system and fault distance is piecewise linear,and the formula of impedance fault location method was deduced as a kind of supplement for T-F short circuit fault location scheme.Secondly,according to the actual situation that rail and protection line of high-speed railway is completely horizontal connection,the CPW current fault location scheme is presented,by the analysis of T-R, and T-PW current of fault case of all parallel AT power supply system which containing the protection line,combine with the "AT neutral current ratio fault location method" formula,the CPW current fault location scheme is studied,the fault location can fast be determined within the scope of1.5km.then more accurate fault location and fault distance measuring formula will be used.Finally,the simulation model of all parallel AT power supply system fault location will be established,the impedance fault location method, the fault location scheme for CPW current and the influence of short circuit transfer impedance, the AT leakage impedance, rail to earth leakage conductance on the CPW current ranging accuracy in the actual situation was researched through simulation,The simulation results show that the impedance fault location method can be accurate for T-F fault distance measurement under the condition that"AT neutral current ratio fault location method"fails,the precision of the range will change along with the change of the distance between the location of the traction substation and the fault location, the farther the distance between the location of the traction substation and the fault location, the distance-measuring error is greater, the CPW fault location scheme can meet the needs of the actual fault location, the farther the distance between the location of the traction substation and the fault location, the distance-measuring error is small.