Research On Transmission Line Fault Location Based On Power Frequency Quality

Fault location for HV transmission lines can promptly and accurately detect the fault point. It not only can repair the fault transmission lines, remove a hidden peril of insulation, but also plays a significant role on power system's running safely, stably and economically. This paper presents the principle of transmission line fault location based on power frequency quality. The filtering algorithm based on improved full-wave fourier algorithm and fault location algorithm based on distributed parameter model of transmission line are discussed in this thesis. The equation of uniform transmission line is derived, which is based on the distributed parameter line module. The decoupling principle of transmission lines after post-fault is discussed in detail. Equations of location are also derived based on one-terminal or two-terminal data, which lay a theoretical foundation for the following research.The filtering effects determine the accuracy of fault location. Four improved full-wave fourier algorithm of filtering are given, and systematic researches of simulation are used to compare their characteristics of filtering. Some helpful summary and the existing problems are also mentioned in this paper, and appropriate filtering algorithm for fault location is proposed in the end.Fault location algorithm using one-terminal data can't eliminate the influence of fault resistance and the contralateral source impedance, which restricts its further application. However, the fault location algorithm using two-terminal data can totally solve this problem and are more accurate. As the development of communication technique, it possesses a certain condition for two-terminal location algorithm to apply into reality. The distributed line module is accurate while it makes location equation nonlinear. Newton iteration is a classical solver for nonlinear equation, but it requires initial value of iteration to be suitable and the computational complexity of solving equation is high. Quasi-newton iterative computation is introduced to solve the nonlinear equation and the recursive algorithm for jacobian matrix decreased computational complexity, it maintains the specialty of super-linear convergence of solving equation. Only the two-terminal fault location algorithm with asynchronous data, allowing the parameter of transmission line to alter, can be of practical value. Fault distance, asynchronous angle of two-terminal power frequency quality and the parameters of transmission line act as unknown variables in the paper. Quasi-newton iteration is used to solve the location equation and extensive simulation work is done. The simulation results show that the proposed method can eliminate the influence of fault location and types of fault, and it is feasible at any point on the whole line.