Study On Traveling-Wave-Characteristics Analysis And Improved Fault Location Method For High-Voltage Transmission Line

With the increasing scale of power system, high voltage and extra high voltage network rapid development, higher requirement is put forward on the fault location method of transmission line. The fault point should be found quickly, accurately and intelligently, in order to repair the fault and shorten the outage time, which plays a important role in safe and economical operation for power system. Compared with the traditional fault location method, the traveling wave location method has many advantages, such as with no effect of transition resistance, CT saturation,system operation mode and so on. But there are still some problems that need to be further studied and improvedThis paper first analyzes the propagation characteristic of traveling wave. The polarity characteristic and it's influencing factors of initial fault generated travelling wave of transmission line are studied. The polarity characteristic of initial fault generated current travelling waves is the same at both ends of fault transmission line, while it's opposite for the non-fault line. The initial fault generated voltage traveling wave polarity of each bus is the same. Bus structure does not affect the propagation characteristics of initial fault generated current and voltage traveling wave. The bus capacitance enhances the current reflection wave, while weakening the voltage reflection wave. The transition resistance only affects the amplitude of the initial fault generated traveling wave, and doesn't affect it's polarity. The fault inception angle may change the initial fault generated travelling wave polarity but doesn't change the relative polarity of traveling wave at both ends of the transmission line. The simulation results verify the correctness of the conclusion.Secondly the law of wave refraction and reflection at fault point in different fault types is analyzed. When the non-single phase to ground fault occurs, the 2 mode traveling wave component obtained by using the Clark phase mode transformation matrix is fully reflected at the fault point, which can solve the problem of the reflection wave identification under the condition of non-single phase earth fault. When single phase grounding fault occurs, the arrival time difference between zero and line mode traveling wave increases with the increasing of fault distance. The relative position of the fault point can be detected by using the arrival time difference, and then identify the reflection wave. The exact fault distance can be computed by using the linear model after the reflection wave is determined.Finally the matching condition between the traveling wave detection time and the shortest path of the double end method is analyzed. The corresponding relationship between the traveling wave propagation path and the relative polarity of the initial current traveling waves in different network structures is studied. The transmission network can be simplified by using the relative polarity of the initial fault generated current traveling wave. The random error can be eliminated by comprehensive utilizing multiple sets of data in order to improve the fault location accuracy. Even if the fault slip location device has a larger error, it can achieve accurate positioning. The simulation results verify the correctness of the conclusion.