Research On Traveling Wave Fault Location Method Based On Multi-measurement Points For Hybrid Transmission Line

As the major artery in the clean and efficient energy transportation process,transmission line plays a decisive role in the safe and stable operation of the power system.The rapid development of the national economy puts forward higher requirements for the coverage of the grid,and the structure of transmission line has become more complex.In areas with special geographical environment or limited land resources,the proportion of transmission line with overhead lines and cables that mixed with each other continues to increase.Although the demand for power supply in a certain area has been solved to a certain extent,the difficulty of fault location in transmission line has been increased,and higher requirements have been put forward for fault location.This thesis first studies the application of the relevant principles of wavelet transform and mathematical morphology in fault location.Subsequently,the process of traveling wave fluctuations and transmission characteristics of transmission line were studied,and the traditional traveling wave method was analyzed and evaluated.Based on the analysis of traveling wave propagation process in the event of a hybrid transmission line fault,it is found when the hybrid transmission line fails,the conventional fault location method cannot accurately locate the fault due to the physical characteristics of the hybrid line.In view of the limitations of the traditional traveling wave method in the scope of application,this thesis adopts a fault location method based on multi-measurement points for hybrid transmission line.The general framework of the fault distance measurement system for hybrid transmission line and the specific process are studied.The method of determining the fault interval using the deviation degree and deviation coefficient of power frequency current in its key technology has been studied and analyzed in detail.Through the analysis of arrival time sequence of traveling wave at each detection point,the specific algorithm principle is studied According to the relationship between the arrival time of the first traveling wave measured at the effective measurement point in the fault interval,the fault location is located.This method can calculate the fault occurrence time and traveling wave speed,which is not affected by the fault type and the transition resistance,and has a high accuracy of ranging.Finally,the simulation model of the hybrid transmission line is established according to the actual conditions.According to the theoretical research of this thesis,the effectiveness and reliability of the fault location method for different typical faults are verified.