Study On Application Of CMFB Theory To Traveling Wave Falut Location For EHV Transmission Line

The reliability of HV/EHV transmission line protection is important to the safety and efficiency of power system. Exploring the new theory and approach of transmission line protection is the important problem in the filed of protection. Much valuable fault information is contained in the transient signal when HV/EHV transmission line encounters fault, the relay protection based on transient signals attracts extensive attention.Fault information is the ultimate gist of the relay action. To get the fault information, we must make use of digital signal processing and mathematic tools. At present, transient fault signal of HV/EHV transmission line is analyzed by wavelet transform. However, this method has disadvantages, that is, in the high frequency field, the resolution is low, in the low frequency field, the resolution is high. But plenty of information is contained in the high frequency filed of the fault signal. Considering that, the wavelet transform has it's disadvantages on analyzing the transient fault signal of power system. wavelet transform based fault location has difficulty to differentiate the polarity of wave heads, which means it can't decide which half-line the fault occurs. Therefore, the application of multi-rate filter banks theory on the fault location based on traveling waves of EHV is researched in this paper. The main productions of this paper are as follows:1. Present the fault location based on traveling waves of EHV using multi-rate filter banks theory , it has advantage as good real-time capability for multi-rate filter banks can extract the information contained in the high frequency fault signal parallelly.2. Using the SIMULINK in MATLAB to construct the model of three phase HV/EHV transmission lines's fault , and utilize the designed CMFB to analyse the transient signal to judge whether the fault occurs and it's rough region. Do MATLAB simulation on the method and the results indicate that the method can not only differentiate the polarity of wave heads , but also achieve accurate fault location.