Study On Fault Location Algorithm For High-Voltage Transmission Line Based On Pmus

For the high-voltage transmission line’s fault location algorithm, the parameters of transmission lines are usually taken as known amounts. However, the actual line parameters will vary as the environment changes, at the same time, the parameters and the actual system, operating conditions have a great relationship, thus there exists a big uncertainty. As the power system itself is a very complex dynamic system, when disturbances, faults, etc. appear in the system, a variety of complex dynamic processes will inevitably occur, as the result, these factors will affect the actual parameters of the line. In recent years, with the development of Wide Area Measurement System(WAMS), the advantages of its global measurements, strong synchronization and high precision have provided favorable conditions for online parameter estimation.To solve above problems, this paper presents a fault location method based on the equivalent line parameter model under dynamic conditions The distribution regularities of line parameter estimations are analyzed. The line parameter values are corrected in the reference value by combining the online estimation of line parameters with real-time parameter correction. The method is able to correct the effects of surroundings and system dynamic conditions on the line parameters in real-time, thereby significantly improves the fault location accuracy. PSCAD/EMTDC software is used to simulate various conditions in order to verify the proposed method and to give comparative analysis for several existing methods in the literature. Simulation results show that:comparing with a variety of algorithms in existing literatures under dynamic conditions, this method has a higher fault location accuracy and the location results are stable and reliable; in addition, it is not sensitive to transition resistance, fault type and fault location, etc.Under the existing power grid distribution, flexible AC transmission system(FACTS) technology is an effective means to improve the economical efficiency and reliability of the transmission system, so it is widely used in domestic long-distance high-voltage transmission network, and as the smart grid’s construction is comprehensively promoted, FACTS must have more broad application prospects in the future. When adding FACTS devices to transmission lines, they can rapidly and flexibly regulate network parameters and certain operation parameters, optimize the power flow distribution of system, improve the capacity of transmission, the voltage quality and the system stability, balance the reactive power distribution, reduce line losses and so on. Nevertheless, FACTS devices also has brought new problems for protection and fault location of transmission lines:FACTS devices destroy the uniformity of transmission line parameters, making the line parameters becomes discontinuous; simultaneously with the structure and function of FACTS devices becoming more complex, leading to their flexible and variable operating status which are very difficult to determine, thus increasing the difficulty of protection and fault location.To solve above problems, this paper studies the two-terminal fault location algorithm based on double ended PMUs measurements for transmission lines containing FACTS compensation devices. First aid power system electromagnetic transient simulation software PSCAD/EMTDC, transmission lines’ simulation models with various types of series and parallel compensation devices were established, laying the foundation for the subsequent simulation studies; then analyzed the characteristics of transmission lines with series and parallel compensation devices separately and summarized existing research methods. Finally, based on distributed parameter line model and double-ended synchronized phasor estimations, established the fault location equation, then utilized a simple one-dimensional variable step search method to solve the equation and get an accurate fault position result.A variety of PSCAD/EMTDC simulation tests under different conditions show that the algorithms are correct and effective, and can yield an accurate fault location estimation independent of the compensated devices’ operation mode or status. In addition, the simulation results still show that the algorithms are not sensitive to transition resistance, fault type and fault location, etc.