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This paper presents novel power system transmission-line fault-location algorithms without requiring transmission-line parameters. The voltages and currents from both ends of a line are taken as inputs and no synchronization is required. Both prefault and fault data may be utilized. The proposed methods are based on a distributed parameter line model and, hence, fully consider the impacts of shunt capacitance of the line. Positive-sequence line parameters may also be estimated as a byproduct. No assumption on the source impedance and fault resistance is made. Evaluation studies based on Electromagnetic Transients Program (EMTP) simulation data demonstrate that the new methods are able to achieve quite accurate estimates. Index Terms--Distributed parameter line model, fault location, transmission-line parameters.

Transmission line protective relaying algorithms usually require transmission line parameters as inputs and thus accuracy of line parameters plays a pivotal role in ensuring the reliable performance of relaying algorithms. Online estimation of line parameters is highly desirable and various methods have been proposed in the past. These methods perform well when the measurements utilized are accurate; they may yield erroneous results when the measurements contain considerable errors. Based on nonlinear optimal estimation theory, this paper puts forward an optimal estimator for deriving the positive sequence line parameters, capable of detecting and identifying the bad measurement data, minimizing the impacts of the measurement errors and thus significantly improving the estimation accuracy. The solution is based on the distributed parameter line model and thus fully considers the effects of shunt capacitances of the line. Case studies based on simulated data are presented for demonstrating the effectiveness of the new approach. Index Terms--Bad measurement detection and identification, distributed parameter line model, non-linear estimation theory, transmission line parameter estimation.

Diverse transmission line fault location algorithms have been proposed in the past depending on measurements available. Existing algorithms usually require measurements captured from buses of a faulted line. By taking advantage of the bus-impedance matrix technique, this paper presents a possible fault location approach for single-circuit lines utilizing only voltage measurements from one or two buses, which may be distant from the faulted line. With the addition of a fictitious bus where the fault occurs, the transfer impedances of this bus and other buses are revealed as a function of the fault location. Based on the relationship between the bus voltage change due to fault and the transfer impedance, the fault location can be derived. Shunt capacitance of the line is ignored first and then fully considered based on distributed parameter line model. ElectroMagnetic Transients Program simulation studies have shown quite encouraging results. Index Terms--Bus-impedance matrix, distributed parameter line model, fault location, single-circuit transmission line.

Various transmission line fault location algorithms have been proposed in the past depending on the measurements available. These algorithms perform well when the measurements utilized are accurate; they may yield erroneous results when the measurements contain considerable errors. In some cases, there are redundant measurements available for fault location purposes, and it may be possible to design an optimal estimator for the fault location based on nonlinear estimation theories. This paper aims at proposing a possible method for deriving an optimal estimate of the fault location that is capable of detecting and identifying the bad measurement data, minimizing the impacts of the measurement errors and thus significantly improving the fault location accuracy. The solution is based on the distributed parameter line model and thus fully considers the effects of shut capacitances of the line. Since field data are not available, case studies based on simulated data are presented for demonstrating the effectiveness of the new method. Index Terms--Bad measurement detection and identification, distributed parameter line model, fault location, nonlinear estimation theory, optimal estimator.

A novel concept for power quality study is proposed. The concept integrates the power system modeling, classifying and characterizing of power quality events, studying equipment sensitivity to the event disturbance, and locating point of event occurrence into one unified frame. Both Fourier and wavelet analyzes are applied for extracting distinct features of various types of events as well as for characterizing the events. A new fuzzy expert system for classifying power quality events based on such features is presented with improved performance over previous neural network based methods. A novel simulation method is outlined for evaluating the operating characteristics of the equipment during specific events. A software prototype implementing the concept has been developed in MATLAB. The voltage sag event is taken as an example for illustrating the analysis methods and software implementation issues. It is concluded that the proposed approach is feasible and promising for real world applications. Index Terms--Pattern classification, power quality, signal processing, wavelet transforms.