Research On Traveling Wave Ranging Method Of Overhead-Cable Hybrid Lines

The line carries the task of transmitting and distributing electric energy,which is a link between the preceding and the following in the whole power system.The upper power plant converts the energy into electric energy through the motor,and the lower power plant converts the power into industrial power and residential power.Once the line fails,the complete link of transmission and distribution is broken,the stability is destroyed,and even economic losses are caused.Accurate and fast fault location,timely and reliable restoration of power supply,so as to effectively improve the reliability of the power grid and enhance people’s happiness.With the development of the Internet of things,it is of great value to ensure the sustainable and reliable power supply of the first ring.Firstly,this paper sorts out the categories of fault location methods,and divides them into two categories,namely impedance method and traveling wave method.The use of impedance method is restricted by many factors,and its accuracy is not as good as traveling wave method,which has been gradually eliminated.Then the traveling wave method is decomposed step by step,and the research status at home and abroad is described.The principle and concept are introduced from the basic concept of traveling wave and motion characteristics,and the reasons and principles of the selection of various information processing methods such as phase mode transform and wavelet transform are also introduced in detail.Secondly,the development and operation of atp-emtp simulation software are introduced,and the model is built in the simulation software.The model has two terminal power supply,four outgoing lines and one branch line,and is an overhead line cable hybrid line.The distance measurement method studied in this paper is a three terminal information detection method for overhead line cable hybrid transmission line.Through the simulation and analysis of examples,the method meets the requirements of distance measurementaccuracy,and its advantages are that it does not need to analyze the complex refraction and reflection characteristics of traveling wave,and it does not need to obtain accurate traveling wave velocity.Finally,based on the three terminal information detection method and the model in the simulation software,the waveform is obtained,and then the data is imported into the MATLAB simulation software to decouple the phase modulus transform,filter and de noise the wavelet transform,extract the mutation point from the modulus maximum,and substitute it into the formula to select the section and calculate the distance to get the final ranging result.Through two kinds of comparative simulation,one is to compare the results under different fault conditions,and the other is to compare the results under different fault location methods.It shows that the three terminal information detection method is suitable for different working environments,which is in line with the standard of actual location accuracy,and has good development potential.