Research On The Overhead Transmission Line Fault Type Diagnostic Methods Of Guangdong Power Grid

High voltage overhead transmission line is an important part of the power system, but it is easily influenced by environment, weather and other factors, for exposing in the air, and lead to various types of faults. These faults can be divided into two categories, which are transient faults and permanent faults. Actually, in the power system operation, some serious system accidents were often caused by lacking of distinguish the fault type of the line timely and accurately. Therefore, it has important theoretical significance and engineering practical value to study a safe and effective fault diagnosis method for power system’s safety and reliable operation.The recorded data in the transmission line contains the important information of the line and the system fault, and the useful information of the fault recording data is very important for monitoring and keeping the power system operate in safety and stabilility. In this paper, a new method of fault diagnosis based on line fault recording data is presented. In this method, the generalized correlation function between the line voltage and current recording data is the information source. And the discriminant function is a function of generalized correlation function of time delay signal. The numerical distribution of the long time discrimination function is calculated. If the correlation coefficient between the fault data and the fault data is low, and the time is maintained for a long time, it can be diagnosed as a permanent fault; If the correlation coefficient between the fault data and the pre fault data increases gradually, the initial diagnosis can be diagnosed as transient fault. The fault resistance can be diagnosed according to the relationship between the number of fault data and the number of pre fault data. A method for constructing characteristic spectrum of fault process is proposed. The characteristic spectrum of the fault process includes the mutual correlation coefficient between the delay data and the fault data. The changing regulation and trendcy of correlation coefficient corresponding the development process of line fault, which constitute a series of fault process characteristic spectrum, and even can be seen in the process of the switching operation of the system and its effect. The correlation coefficient can provide more information for further diagnosis of transmission system changes with displacement factor tau. The simulation and field data verify the validity and practicability of the fault diagnosis method and fault process spectrum.The fault diagnosis method and the fault process spectrum are presented in this paper, itself does not need any information within the system, as long as the line at both ends of the recorded data, in theory, is completely black box method, has the versatility and universality, and thus has the maneuverability and practicability.