Research On Accurate Fault Location Of High Voltage Transmission Line

High voltage power transmission line has the characteristics of high voltage level,high transmission power and low power transmission loss,which makes the development of high voltage,high voltage and extra high voltage in recent years.The accident of high voltage transmission lines will cause great loss to the national economy and people's lives and property,so it is an important task to guarantee the safe operation of the high voltage transmission lines.In order to find out the fault position and restore power supply as soon as possible,it is very important to choose a fast and accurate method.At present,there are two kinds of fault location method which are traveling wave method and fault analysis method,the two methods have their own advantages and disadvantages,but the traveling wave method is widely used because of its simple calculation and wide adaptability.The current use of traveling wave method is two terminal traveling wave method.Analysis of traveling wave signal transmission line at both ends of two terminal traveling wave method,it does not need to consider the impact of transmission line parameters and transition impedance,however,the traveling wave signal at the two ends of the transmission line is needed to be collected,because there is no synchronization between the two ends of the traveling wave signal,there is a big error in the ranging accuracy.There are two kinds of high voltage transmission lines,which are single transmission line and T-type transmission line.The through research of fault traveling wave at the fault point and the bus side of the refraction and reflection phenomenon,for single transmission line and T-type transmission line traveling wave propagation process are analyzed,using traveling wave propagation time difference concept for accurate fault location method is proposed.(1)For single transmission line.Firstly,it is assumed that the failure occurred at the midpoint of the transmission line,the transmission line is divided into two sections,the traveling wave propagation process is analyzed and the time difference of the fault traveling wave transmission to the two sides bus is recorded,analysis and comparison of the time difference between the traveling wave transmission and the two bus bars in the actual fault,so it can locate the fault section.According to the fault section,we can know the type of the traveling wave signal received by the bus side second times,and then the precise fault location can be realized by the single end of the traveling wave.(2)For T-type transmission line.Firstly,it is assumed that the branch points of the transmission line and the midpoint of each branch line fault occurs,the transmission line is divided into six sections,the traveling wave propagation process is analyzed and the time difference of the fault traveling wave transmission to the two sides bus is recorded,analysis and comparison of the time difference between the traveling wave transmission and the two bus bars in the actual fault,so it can locate the fault section.According to the fault section,we can know the type of the traveling wave signal received by the bus side second times,and then the precise fault location can be realized by the single end of the traveling wave.In this paper,by using the above method,the source of the traveling wave signal is effectively identified,and then the fault location is carried out by using the single end of the traveling wave,it does not need to consider the length of transmission line is not accurate and the time of traveling wave fault location on both ends of transmission line can not be precisely synchronized,so the ranging results than the two terminal traveling wave method is more accurate.The PSCAD simulation model of single transmission line and T type transmission line is built and the simulation is carried out,the PSCAD simulation was used to obtain the traveling wave signal using MATLAB for data analysis to verify the reliability of the proposed method in this paper.Through the simulation analysis,the research method of fault location of high voltage transmission line is compared with the traditional double end fault location method,which has greatly improved the accuracy of the distance measurement.