Detection Methods Of Fault Travelling Wave In Transmission Lines Based On Magnetic Field Measurement

Power grid is one of the most widely covered and complicated construction man-made system, transmission overhead line cross through mountains and plains, cable line in city buried underground deeply, it's extremely difficult to find out the fault point when the fault occurs. It might trigger multiple faults, even lead to large area power outage if the fault could not exclude in time, which endangered the grid security seriously. The traveling wave based fault location techniques existing now are detect fault generated traveling waves from transformer substation, and likely to suffer the effect from the complicated environmental such as noise jamming from transformer substation, which limited it's degree of detect accuracy. Therefore, essay researched a new method of detect traveling wave produced by transmission line fault based on magnetic-field measurement.This paper firstly analyzed the basic theory of magnetic field, elaborated three methods of the magnetic field distribution around the transmission lines, such as charge equivalent method, finite difference method and finite element method. Compared with the field range, boundary shape, bundled conductors and media type, the finite element method was more suitable for the transmission lines with complex boundary shape than other methods, which could get more accurate transient magnetic field signals without approximate assumption as long as the conductors dissection was enough. Therefore,according to the establishment of the transient magnetic field simulation of the Maxwell software based on finite element theory, various feature information of the transient fault traveling wave could be obtained by detecting the magnetic signal. The analysis of transient traveling wave signal based on the EEMD method, which could accurately detect the arrival time of transient traveling wave, and effectively improve the detection accuracy of the transient traveling wave signal of the smart grid. In addition, a new detection system of the transmission lines fault traveling wave was also introduced in this paper.The traveling wave detection device was composed of the magnetic field sensor, the central processing unit, the beidou satellite clock unit, the 4G communication unit and the solar energy power supply module, which were placed in transmission line tower, but the remote terminal computer was placed in the substation. When a fault occurred, with the interaction between the various functional units, the traveling wave detection device could detect and send the fault traveling wave to achieve fast and accurate fault detection, which is practiced and feasible.This paper made a detailed research to the fault location method for transmission line based on magnetic measurement by basic theory,analysis of method and practical application.The result indicated that this new method could accurate extract the smart grid transient traveling wave signal which had significant meaning to the operation of power system.It also provided a new idea to researching on fault location for transmission line.