A Fault Location Method For Overhead-Cable Hybrid Transmission Lines And Fast Restoration Technology Research

Under the such case of line insulation damage or a thunder strike,power lines prossess the highest probability to occur a single-phase-grounded fault with transient fault properties.Nevertheless the traditional reclosing device can’t distinguish transient fault from permanent fault correctly,the reclosing operation could be implemented uniformly.But the cable fault of hybrid lines belong to the permanent fault,it’s easily to cause a secondary high-voltage shock to electrical lines and equipments through switching circuit breaker blindly,and it will influence insulation performance of lines and destroy the power network,thence causing a unpredictable serious consequence.Thus,to realize adaptive reclosing,it is of great actual economic significance to study the fault location method and rapid restoration device for hybrid lines,which could reduce the outage time effectively.For that problem,the produce and catadioptric process of the fault traveling wave was analyzed firstly in this paper.Considering the fault characteristics in hybrid lines,a non-parameter-threshold-setting fault location method has been proposed.First,the standard array of traveling wave arrival time difference between the two terminals of line was built with more faults simulated in the different positions of the line.Second,when the actual fault happened,the arrival time difference was measured and compared with each element of the standard array to detect the fault section.Finally,the fault point relative position in the fault section was calculated,and the fault point accurate position was also determined with the position of each tower or cable joint.At the same time,the rapid restoration control principle had been presented in the thesis.By using transient wave signal and polarity,which collected through the specific sensor,it could determined the type of the fault line exploiting section identification and FLA,controlling the close or break of the outlet pressure plate of the reclosing device,thus conducting the adaptive reclosing control and realizing rapid restoration.Also,this paper designed both the software and the hardware of the rapid restoration device for the hybrid lines.The hardware part consists of fault detection module,GPS clock wave recording module,precise fault positioning module,optical fiber communication module and adaptive reclosing lock-up control module.The software part includes the upper computer software and main interface function of the upper computer operating system.Finally,dynamic simulation test of rapid restoration device has been done.And the test results of fault location and reclosing have showed that the device had advantages.Such as,high-accuracy fault location,accurate determination of reclosing,short time of restoration and so on.The max error in fault location is 86 m and response time of reclosing lock-up control is80 ms,which completely satisfy the requirements of the actual application in technical fields.