New approach to the fault location problem using synchronized sampling

Abstract

This thesis presents a new approach to solving the problem of fault location on a transmission line using synchronized data from both ends of the line. The synchronized phase voltage and current samples taken during the fault transient are used to calculate the location of the fault. Time domain models of lines are used as a basis for derivation of two different algorithms. One algorithm is developed using the RL line model and the other one is developed using the traveling wave based line model. The main idea of the fault location concept is based on the general characteristics of any transmission line. At any location along the unfaulted line, the instantaneous values of voltage and current signals are related to the instantaneous values of the corresponding values of voltage and current signals at both ends of the line, line parameters, and distance between that particular location and each of the line ends. This enables the derivation of the generic fault location equation of the following form: [ ] where Lv is the linear operator, VA, t'A, VB, z'B are vectors of voltage and current samples at line ends, d is the length of the line, and x is the unknown distance to the fault point. For a particular transmission line, the generic equation has a unique form that determines the way it is solved. In any case, the Minimum Square Error Estimation Method is used since an overspecified system of linear equations needs to be solved. The performance evaluation of both algorithms was done using the Electromagnetic Transient Program (EMTP) generated data [1]. Obtained results indicate the high accuracy of the approach and its robustness regarding various fault conditions. The following are the conclusions based on the results presented in this thesis: The error of the approach is rather small and almost invariant to the various fault conditions and, hence, the technique provides a robust solution to the fault location problem. The new approach has high accuracy while the computational burden is still kept relatively low. The synchronized sampling technique required for this approach is emerging as a reliable and cost effective practice.