Research On Single-ended Fault Location Based On Combination Of Impedance Method And Traveling Wave Method

At present, traveling wave fault location device has been widely used; the use of traveling wave fault location device has improved the reliability and economy of the transmission line operation according to actual operation experience. With the great progress of smart grid, the digital substation technology is developing rapidly. In digital substations, digital transformers are used in place of conventional magnetic transformer. And proposed data sharing requirements to devices, therefore, traveling wave fault location device need modify accordingly in data format and communication protocol, which leads to interoperability problems between the existing location devices. In this case, double-ended fault location method is difficult to realize. In contrast, single-ended wave method requires only one-end data, it is able to adapt to the situation that only one end of the line is intelligent substation. To develop a reliable and stable single-terminal location method also have some reference value to improve existing devices, and it can greatly reduce the manufacturing and maintenance costs of traveling wave fault location devices.The stability of single-ended impedance method is higher than singled-ended traveling wave method, but the precision of single-ended impedance is relatively lower. The advantages of impedance fault location method and traveling wave method are complementary. A transmission line integrated single-ended fault location algorithm will be proposed, it can improve the reliability of single-terminal location on the basis of keeping high measurement accuracy by combining the advantages of both single-ended impedance fault location method and single-ended traveling wave fault location method. In this paper mainly include the following studies:1. In the impedance method, Differential equation method and phasor iteration method are studied by the researcher, the stability and accuracy of the two methods are compared, and the impact of impedance measurement accuracy and reliability of the relevant factors are analyzed. According to the need of comprehensive single-ended fault location method, choose an appropriate algorithm, and an estimation method of transition resistance is proposed. 2. In the research of traveling wave method, according to the characteristics of single-ended fault location method, the fault current were classified. The first reflected wave is identified making of use of wave polarity identification combined with the length of short-circuit fault lines in the ordinary conditions, In high transition impedance short-circuit fault and other special conditions, recognize the reflected wave head according to the zero sequence network. EMTDC simulation and the actual fault data analysis have proved the effectiveness of the method.3. Proposed a process of transmission line comprehensive single-ended fault locating algorithm, the subject of study, in the research the researcher proposed a method to determine the approximate range of the fault location and estimated transition resistance, then choice wave head identification method according to the resistance estimation results. And identify the wave head at the help of the approximate range of the fault location. EMTDC simulation confirms the validity and reliability of the method.