Fault Location And Fault Comprehensive Analysis For 500kV Transmission Lines

500kV power grid is the backbone of power system.Correct operation of protection and fast and accurate fault location has important economic significance and social value. The paper makes an intensive study of practical method for fault location and fault analysis based on asynchronous fault recorder data. The main work of this paper is summarized as follow:Traditional detection principle of fault starting point is used to fault location of transmission line based on fault recorder. The location accuracy is reduced by the sampling frequency. An improved detection method of phase current fault component is proposed to make up the shortcomings of traditional detection principle. The effect using the improved method is better than the traditional one based on the real fault recorder data of transmission line, and it lays the foundation for double synchronous information needed by two-terminal fault location.Based on the asynchronous data of fault recorder, a practical adaptive two-terminal asynchronous fault location algorithm is proposed. Because the long line parameters are influenced by geography, weather and aging, the practical method reduces the location error and improves the accuracy through online correction. The method also improves the location accuracy by online correcting the asynchronous angle which is caused by the hardware device. Through online detecting the polarity of the double-data of PT and CT, the practical method can be adaptive and avoid the fault location failure due to the polarity inconsistency. Fault type is not necessary combined with the sequence components, so the practical method is more adaptive.The paper do some fault comprehensive analysis of transmission line based on asynchronous fault recorder data, including theoretical and practical analysis of fault phase selection, fault impedance and system equivalent impedance. The paper also does some analysis of protecting operation including the analysis of distance protection, current differential protection and directional pilot protection on fault lines Comparing with the results of the fault recorder can check the correctness of the theory and algorithm. The paper analyzes the fault transmission line from theory to practice and checks the theory through the practice.Based on the GUIDE module of MATLAB, this paper develops the 500kV transmission line fault analysis and location system, which has friendly interface and modular operation. The platform includes a menu bar and seven function modules. The menu bar can import the transmission line parameters and the fault recorder files, and introduce the brief principle and other instructions. All stored fault data files use the database. The function modules incorporate electric, wave, fault phase selection, fault location, transition impedance, protection analysis and system equivalent impedance module. The electric module can show the phase and sequence component; the wave module can complete the waveform zoom and selection display function; the fault phase selection module can complete the fault phase selection of the lines; the fault location can complete the fault location of different principles; the transition impedance module can calculate the transition impedance; the protection analysis module can realize the distance protection, current differential protection and directional pilot protection function; and the system equivalent impedance module can calculate the system equivalent impedance.