Research On Fault Location Method Of High Voltage Transmission Line

The power system consists of four parts: production,transmission,distribution and consumption.The transmission line undertakes the task of delivering electric energy.With the development of national economy and the expansion of state grid,the requirement of transmission capacity is increasing rapidly.Therefore,accurate fault location analysis of high voltage transmission lines is an important guarantee for the safe and stable transmission of electric energy.After studied and analyzed the fault location methods of high voltage transmission line,the specific works are as follows:Firstly,the background and significance of the research on high voltage transmission line fault location are introduced,and the types and characteristics of transmission line fault location are discussed.According to the different methods of fault location,the fault location algorithms are classified.The requirements and influencing factors of distance measuring device are described specifically.On the foundation of the research on the fault location at home and abroad,the characteristics and applicable conditions of algorithms are analyzed and compared.Based on clarified the fault analysis method and the traveling wave fault location method,the problems needed to be solved are put forward.Secondly,the power frequency and impedance fault location algorithms need the technical parameters of the transmission line in order to calculate the distance.Focus on this disadvantage,an algorithm which without the parameters of the transmission line are put forward.According to the positive and negative sequence of voltage and current,the fault location consequence can obtained.With the application of Global Positioning System(GPS),the voltage and current at both ends of the line can be collected simultaneously.Through deduced the formula of fault location in detail.The MATLAB software was used for the simulation test under setting the different voltage levels,fault types,fault distance and transition resistance.The simulation results verified: the method has the characteristics of high accuracy.Thirdly,a phase-mode transformation matrix is introduced,which can reflect different fault types of transmission line by single-mode components.Through analyzed the main factors of travelling wave fault location method and considered the transmission of travelling wave is irrelevant to wave speed,the fault distance can be obtained by the moment of the initial traveling wave reached the line and the length of the line.In view of the complicated characteristic of travelling wave and the inconvenience of captured the wave head,selected the IMF1 which was decomposed by Empirical Mode Decomposition(EMD)as the research target to identify the traveling wave head.Carried on the Hilbert-Huang transform to obtain the instantaneous frequency graph,and calculated the maximum value.Afterwards,found out the time of traveling wave head arrived by the maximum value,achieved the fault location.The MATLAB/SIMULINK platform was utilized for simulation test,which proved the algorithm can identify the moment of traveling wave arrived under the different fault types and the result of fault location without the affection of transition resistance.Because of the high accuracy and stability of the method,it can be suitable for practical application in engineering.Finally,summarized the research and described the future development direction in fault location.Experiments showed that the impendence fault location method based on the power frequency and the traveling wave method based on HHT transform,both can achieve the fault location accurately and have a positive effect on the safe and stable operation of the power system to ensure power quality.