Research On Traveling Wave Fault Location Method For High Voltage Overhead Line And Cable Hybrid Line

With the rapid development of China’s economy,city and township power load is increasing,the traditional overhead line has been unable to meet China’s city and township power development needs,on the one hand,the construction of overhead lines will occupy a lot of land resources,is not conducive to the rational use of land resources,on the other hand,complex overhead lines occupy urban building space,is not conducive to the construction of modern city.Because of its benefits of laying underground and convenient for urban modernization,power cables have been widely applied in the power grid.The power lines have also evolved from simple overhead lines to overhead line cable hybrid transmission lines and mixed transmission lines with T branches.The evolution of power line structure has put forward higher requirements for the location and search of power line fault.Traveling wave method is less influenced by the type of fault and transition resistance and so on,so it is widely used in fault location of transmission lines.According to the wave head of traveling wave acquisition types,traveling wave method is divided into single end traveling wave distance measurement method and double end traveling wave method,one end method has higher precision of distance measurement among the method,but it is distinguished that the wave head properties of each test is the difficulty of single end range finding.Therefore,this paper is based on the transient traveling wave propagation characteristics of the hybrid line fault,traveling wave fault location method for high voltage hybrid line based on interval ratio principle and traveling wave fault location method for T-type transmission line are proposed.The main research work in this paper is as follows:(1)This paper uses theoretical analysis and simulation verification to do the research of the mechanism of production and propagation characteristics of fault transient traveling wave in depth.On this basis,the principle of single line traveling wave distance measuring principle for hybrid line is expounded and the influence of transition resistance,fault inception angle,fault type,fault position on the fault voltage traveling wave,current traveling wave propagation characteristics and traveling wave fault location precision is explored in detail.(2)A interval ratio principle traveling wave fault location method is proposed for different high voltage hybrid line connection structures.Firstly,the time difference between the traveling wave propagates from the line end to the both ends of the line and from line connection point to the both ends of the line is used as the setting value to construct the ratio interval.Then,the time difference between the first transmission to the both ends of the fault traveling wave is compared with the setting value to determine the line section of the fault point.Finally,the location result is calculated by the principle in the fault location.(3)A combined traveling wave ranging method of T transmission line is proposed for T-type transmission line connection structures.Firstly,the fault section is determined by the principle of two terminal ranging,then the fault distance is obtained by the principle of single terminal ranging.(4)The simulation model of the high voltage hybrid line and T-type transmission line was established by PSCAD respectively.Different fault points are simulated,and the simulation results are transformed by MATLAB software,and the traveling wave propagation data are obtained,and the proposed methods are verified.The traveling wave location method proposed in this paper has strong versatility.When the line fails,it can effectively reduce the losses caused by failures and has wide application space.