| At present,the key problem in the research of double-terminal traveling wave fault location is that the double-ended must be equipped with high-precision and high-stability real-time clocks,and the double-ended clocks must be absolutely synchronized.At the same time,the uncertainty of traveling wave velocity has a great influence on ranging accuracy.Aiming at the problems existing in the current two-terminal traveling wave fault location methods,two-terminal traveling wave fault location methods based on absolute time synchronization and relative time synchronization are compared and analyzed.It is found that the two-terminal traveling wave fault location method based on relative time synchronization can obtain the absolute time when the initial traveling wave arrives at both ends of the line without external synchronization device timing the two-terminal clock.Two-terminal fault location is realized.In this paper,a traveling wave fault location scheme based on optical fiber time synchronization is presented by using optical fiber as communication channel.In this scheme,two-terminal traveling wave location method based on optical fiber time synchronization and traveling wave location method to eliminate the influence of wave velocity are proposed.The main research contents are as follows:1.The research status of traveling wave fault location technology and the application status of optical fiber communication in fault location are summarized.The idea of fault location based on the combination of optical fiber communication and traveling wave principle is put forward.2.The principle of two-terminal traveling wave fault location method based on absolute time synchronization and relative time synchronization is expounded,and the key technical problems and solutions of the two methods are analyzed.The advantages and disadvantages of the two methods are compared and evaluated.Finally,optical fiber is selected as the communication channel,and a traveling wave fault location scheme based on optical fiber time synchronization is proposed.3.The overall ranging system structure of the proposed location scheme is analyzed.The key technical problems in the scheme are put forward.The measurement methods of transmission delay and time delay of pulse signal under special channel and multiplexing channel are analyzed in detail,and the selection of pulse signal and its working mode are explained in detail.4.A two-terminal traveling wave ranging method based on optical fiber time synchronization is proposed.Signal transceiver devices are arranged at both ends of the circuit,and the time information obtained at both ends is used for ranging.The average value of ranging results at both ends is taken to get the final ranging results,which can improve the ranging accuracy and reliability.5.A traveling wave ranging method is proposed to eliminate the influence of wave velocity.Firstly,the time difference between the initial traveling wave and the pulse signal is used as the criterion to distinguish the fault zone.Then the wave velocity parameters are eliminated by using the formula.Finally,the distance measurement formula without wave velocity is obtained,which eliminates the influence of wave velocity on the ranging results.6.The fault model of 220 kV high voltage transmission line and point-to-point optical fiber communication system model are built.The traveling wave characteristics of the faults under different fault distances are calculated and analyzed.The accuracy and generality of the two locating methods proposed in this paper are verified.The simulation results show that the two-terminal traveling wave fault location method is realized under the condition that the two-terminal pair of time is not needed.The accuracy of fault location meets the requirements of practical engineering applications.The method proposed in this paper can further improve the ranging accuracy and reliability by eliminating traveling wave velocity.The fault location scheme based on optical fiber time synchronization proposed in this paper can be used alone in the project or in combination with the double-end ranging method using GPS synchronization.The two methods can ensure the reliability of ranging results and have a wide application space. |
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