Research On Multi-point Faults Location Method Of Transmission Line Network

The detection and maintenance of cable faults can provide a strong guarantee for the continuous and high-quality supply of power and communication systems.Among them,the detection of cable soft faults can prevent the occurrence of system accidents,which is extremely important for maintaining the stability and safety of system operation.At present,there are many methods for detecting a single cable fault,but the problem of multi-point faults in the cable network still needs to be studied in depth.For a cable network with multiple points of failure,the commonly used methods are often easy to find hard faults(grounded or open through a small impedance),and unidentified soft faults may develop into hard faults as the system runs,threatening the safe operation of the system.Therefore,research on methods with multi-point fault location function is a very worthy research direction.This paper has carried out research on the multi-point fault location method of cable network,and the specific work is as follows:(1)Based on the transmission line theory,this paper uses the dual-port network scattering parameters and time reversal method to realize the multi-point soft fault location of a single cable.In order to verify the effectiveness of the method,a single branch cable network with two soft faults was built in the laboratory,and fault location experiments were carried out based on the scattering parameters measured by the network analyzer.The results show that the time reversal method can achieve two soft faults Position recognition,and has a very good positioning accuracy.(2)The acquisition of three-port network scattering parameters is a prerequisite for multi-point fault location in a three-branch cable network.In order to solve the problem that a two-terminal network analyzer cannot achieve direct measurement of multi-port network scattering parameters,this article first gives the use of multiple measurements of two-port network scattering The steps of obtaining the scattering parameters of the three-port cable network with the parameters,and then combined with the time inversion method,realized the multi-point soft fault location of the three-branch cable network,and carried out experimental verification.(3)For cable networks with more branches,the process of obtaining multi-port network scattering parameters by using multiple dual-port scattering parameters is still complicated.This paper implements a multi-branch cable network multi-point fault location that combines dual-port scattering parameter measurement and time inversion.Compared with the method based on multi-port network scattering parameters,the method can effectively reduce the number of measurements of two-port scattering parameters and simplify the implementation process.The specific process of this method is as follows: treat every two ports in the network as a single-branch cable model with multiple soft faults,and combine the time reversal method of single-branch cable fault location to locate the bifurcation point and The location of the fault point;by repeating the above steps,the locations of all fault points in the network can be located in sequence.The effectiveness of this method is also verified by laboratory experiments.