A Novel Study Of Fault Location Of Lines Based On Transient Travelling Wave

It goes without saying that power is of importance for social development. The primary task of power grid corporation is to ensure the reliability of power supply.The structure of power grid is complicated and fault is inevitable. So the research of fault location can not only help power grid maintenance crews restore power service without much delay but also eliminate hidden dangers in the grid. This paper mainly introduces multi-terminal transmission network fault-location,and selection of the fault feeder and the location of the fault point in the neutral indirectly earth systems.S-transform is performs good localization properties in the time-frequency domain, therefore, S-transform is applied to the aerial modal components of synchronized measured voltages at all the terminals to extract the Nyquist frequency components of transient traveling waves. The moment corresponding to the maximum component in the Nyquist frequency component is exactly the initial traveling wave arrival time. Using the wave velocity corresponding to the Nyquist frequency component as the calculation wave velocity, solved the problem of the wave speed mismatch the time. Based on double-terminal traveling wave theory and the result of the indentification theory for fault section, the final fault distance can be achieved.Two programs of fault section location is put forward in this paper, the one is to investigate line segments one by one, the other is to classify the multi-terminal transmission network into two types of branches and trunk section then judge the fault section.When small current grounding fault caused by damage of insulation occurred in the neutral indirectly earth systems, the phases of initial current traveling wave front in fault line and sound lines are opposite till the return of reflection traveling wave of any sound line. The result of the first difference in the vicinity of the sampling point which is exactly the initial traveling wave arrival time will ultimately determine the fault line. S-transform energy relative entropy of fault voltage and fault current of feeders within a period of time can also distinguish between sound lines and the fault line whose entropy significantly larger than others. And the performance of this method is immune to fault inception angle and fault resistance. A new method for fault location in the neutral indirectly systems based on transient phase current is proposed in this paper. The correlation coefficient of the transient fault phase currentand the transient sound phase current is totally different before and after the fault point. By this means, the fault point can be finally found out. At last, simulation analysis has been done to verify the above conclusions and algorithms and their performance under different conditions.