Transient Analysis Of The Faults On The Double Circuit Transmission Lines And Study Of The Fault Line Selection

Xiluodu right bank-Guangdong HVDC transmission project is one of the mostimportant transmission projects in China. It adopts the design of the double-circuittransmission line on the same tower, which helps to save the land resources and decrease thebuilding expensives. Compared to the single-circuit transmission line, double-circuittransmission line share the same tower with four lines, which creates complicatedelectromagnetic coupling environment. If there is fault on one of the transmission lines, theother circuit lines would also suffer from fault disturbance, which may cause maloperation ofthe travel wave protection of the transmission lines. Since the Xiluodu HVDC transmissionproject was put into operation within one year, there is not much research about thedouble-circuit electromagnetic coupling principle, and the transmission lines were equipedwith travel wave protection. So we need to analyze the fault characteristics on thedouble-circuit lines and figure out a new way to select the fault line, in order to complete thetravel wave protection and improve the stability of the HVDC transmission projects.This essay discribes the travel wave principle and study about the double-circuitelectromagnetic coupling principle. Then analyze the fault characteristics with idealtransmission line model and realistic mdoel. Based on the mathematic analysis, eplain thesimulation results of faults on the double-circuit transmission lines by using thePSCAD/EMTDC simulation tool. Then use the Time-Frequency Analysis of S transform toextract the fault characteristics from the travel wave of double-circuit lines, and find a methodto select the fault lines when fault occurs on the transmission line. This essay provides a wayto acomplish the fault line selection by using S transform, and give the simulation provement.