Study On Fault Location Of High Voltage Transmission Line Based On Hilbert-huang Transform

High voltage transmission line is a import component of power system. Fast and accurate fault location could discover the insulation hidden trouble and carry precautions. In this way, the reliability can be advanced and a large aggregate loss because of power failure can be decreased.The transient traveling wave signal which generated by fault location of HV transmission line transmitted to each transformer substation of power grid in the speed of light. The traveling waves'arrival time and waveform characteristics were recorded in each substation in order to getting the accurate distance of the failure point. The fault location has high precision. They cannot be influenced by current transformer saturation, low frequency oscillation and fault resistance and so on. The thesis analyzed physical process and transmission characteristics of traveling wave in detail. Then the paper analyzed several algorithms and factors that affecting the precision of fault location based on traveling wave after discussing the theory, types, present situation of studying and trends. The thesis used Hilbert-Huang transform- a kind of method to process nonlinear and non-stationary signals to detect traveling wave signals, in accordance with the transmission characteristics of traveling waves. Intrinsic Mode Functions (IMF) of traveling waves are extracted by Empirical Mode Decomposition(EMD), and then Hilbert transform is applied to calculate the corresponding instantaneous frequency of highest frequency IMF component. The arrival time of traveling wave can be detected by the instantaneous frequency's mutational point.The thesis conducted simulation experiments based on MATLAB, for verifying the validity of the method discussed above. The simulation model came from a literature which had published in public. The two-terminal fault location method which using velocity to calculate and the three-terminal fault location method which excluding the velocity had been used respectively in the experiment. The simulation results were compared with the results that based on wavelet transform. A conclusion can be got from the simulation results, that the fault location results based on Hilbert-Huang transform are more accurate.