Research On Fault Traveling Wave Location Method Of DC Distribution Line

With a large number of distributed power sources and electric vehicle charging piles connected to the power grid,the DC characteristics of the source charge of the distribution network have become more and more obvious,which has promoted the development of the DC distribution network.Fault location is one of the key technologies to ensure the safe operation of the power system.After a short circuit fault occurs on the DC distribution line,quickly and accurately identify the fault line and determine the location of the fault point.It is of great significance for improving the safe operation of power systems and the reliability of power supply.This paper mainly studies the method of locating the fault on the DC side.Due to differences in operating modes and network topologies,the fault characteristics of DC distribution lines are obviously different from those of AC distribution lines,so various fault location methods based on sequence components in traditional AC distribution networks are no longer applicable.The ranging method based on the traveling wave principle has the advantages of high ranging accuracy and little influence by the system operation mode.Therefore,on the basis of studying the initial traveling wave propagation characteristics of DC distribution line faults,this paper proposes a multi-point based Measuring traveling wave ranging algorithm.The main work and conclusions of the paper are as follows:(1)The background and significance of the development of the DC distribution network are introduced,and the fault location methods of the existing AC distribution lines and DC distribution lines are summarized and analyzed.At present,there are relatively few studies on fault location methods for DC distribution lines,and further research is needed.(2)The propagation characteristics of the fault traveling wave in the DC line are analyzed.The DC distribution network has many topological structures,and the propagation characteristics of the initial traveling wave of the fault are different in different networks.The most complex in the ring network requires the algorithm to have good topology adaptability.The characteristics of different traveling wave ranging principles are summarized and analyzed.In the DC distribution network,the multi-terminal method should be used for fault location.(3)This paper proposes a traveling wave positioning strategy based on multi-point measurement information,and constructs a path-based Multi-end traveling wave ranging algorithm at the moment when the minimum fault occurs.Analyze and study the technology and problems involved in the algorithm,realize the accurate calibration of the arrival time of the initial traveling wave of the fault through the wavelet transform,give the method of screening the effective time at the ranging master station,and use Floyd algorithm to search between the detection points of the entire network The shortest path,and finally calculate the matrix of possible fault occurrence time,determine the size of the matrix elements to identify the fault path,and then locate the fault.In the ring network,the fault traveling wave propagation path is not unique,which may lead to wrong line selection.For this,through verification,select the possible fault point,compare the Manhattan distance and give the most similar results to the actual situation.(4)The algorithm makes full use of the fault information recorded by the detection points of the entire network,which improves the reliability of the ranging system.It also has the functions of line selection and ranging and is not restricted by the network topology.Build a double-end power supply model in PSCAD,perform fault simulation,and build DC distribution network models of different topologies,simulate the DC distribution line and DC distribution bus fault scenarios,and extract the fault data to the path-based fault mentioned in this article The traveling wave ranging algorithm at the time of occurrence was tested,and the simulation verified the effectiveness of the algorithm.The research and application of fault location methods for DC distribution lines can speed up fault handling,reduce power outage time and economic losses.The proposed algorithm needs to go to the field for further experiments,and improve the algorithm according to the actual problems encountered.