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In modern power transmission systems, the double-circuit line structure is increasingly adopted. However, due to the mutual coupling between the parallel lines it is quite challenging to design accurate fault location algorithms. Moreover, the widely used series compensator and its protective device introduce harmonics and non-linearities to the transmission lines, which make fault location more difficult. To tackle these problems, this dissertation is committed to developing advanced fault location methods for double-circuit and series-compensated transmission lines. Algorithms utilizing sparse measurements for pinpointing the location of short-circuit faults on double-circuit lines are proposed. By decomposing the original network into three sequence networks, the bus impedance matrix for each network with the addition of the fictitious fault bus can be formulated. It is a function of the unknown fault location. With the augmented bus impedance matrices the sequence voltage change during the fault at any bus can be expressed in terms of the corresponding sequence fault current and the transfer impedance between the fault bus and the measured bus. Resorting to VCR the superimposed sequence current at any branch can be expressed with respect to the pertaining sequence fault current and transfer impedance terms. Obeying boundary conditions of different fault types, four different classes of fault location algorithms utilizing either voltage phasors, or phase voltage magnitudes, or current phasors, or phase current magnitudes are derived. The distinguishing charactristic of the proposed method is that the data measurements need not stem from the faulted section itself. Quite satisfactory results have been obtained using EMTP simulation studies. A fault location algorithm for series-compensated transmission lines that employs two-terminal unsynchronized voltage and current measurements has been implemented. For the distinct cases that the fault occurs either on the left or on the right side of the series compensator, two subroutines are developed. In additon, the procedure to identify the correct fault location estimate is described in this work. Simulation studies carried out with Matlab SimPowerSystems show that the fault location results are very accurate.

The Estimation of Thevenin Equivalent Parameters is useful for System Monitoring and Protection. We studied a method for estimating the Thevenin equivalent circuits. We then studied two applications including voltage stability and fault location. A study of the concepts of Voltage Stability is done in the initial part of this thesis. A Six Bus Power System Model was simulated using MATLAB SIMULINK®. Subsequently, the Thevenin Parameters were calculated. The results were then used for two purposes, to calculate the Maximum Power that can be delivered and for Fault Location.

Fault detection and location algorithms have allowed for the power industry to alter the power grid from the traditional model to becoming a smart grid. This thesis implements an already established algorithm for detecting faults, as well as an impedance-based algorithm for detecting where on the line the fault has occurred and develops a smart algorithm for future HDL conversion using Simulink. Using the algorithms, the ways in which this implementation can be used to create a smarter grid are the fundamental basis for this research. Simulink was used to create a two-bus power system, create environment variables, and then Matlab was used to program the algorithm such that it could be FPGA-implementable, where the ways in which one can retrieve the data from a power line has been theorized. This novel approach to creating a smarter grid was theorized and created such that real-world applications may be further implemented in the future.

Imaging of current in internal conductors through magnetic field detection by magnetic force microscopy (MFM) is of growing interest in the analysis of integrated circuits (ICs). This thesis presents a systematic study of the MFM based mapping of current in model circuits by using force and force gradient techniques. In comparing these two techniques, force was found to have a much higher signal to noise ratio (from ~150 to ~580 times) than force gradient at large tip-sample distances considering the presence of thick overlayers in ICs. As a result, force will have better sensitivity and can therefore be used to detect much smaller minimum currents. We have achieved a sensitivity of ~0.64 µA per square-root Hertz in air and ~0.095 µA per squre-root Hertz in vacuum for force with a pinning field with a probe-circuit separation of 1.0 µm. We conclude that the force technique is superior for the application of MFM current imaging of buried conductors, albeit with reduced spatial resolution. Numerical modeling of the MFM images has shown that the simple point probe approximation is insufficient to model MFM images. An extended model, which considers realistic MFM probe geometries and the forces acting on the whole probe, has been shown to be necessary. Qualitative and quantitative comparisons of the experimental and simulation results with this model are in agreement to within experimental uncertainty. The comparisons suggested that the CoCr film thickness is not uniform on the probe, which was verified by scanning electron microscope cross-section images of the probes cut by a focused ion beam. Most notably, the CoCr film was 1.5 times thicker on the cantilever than on the tip. Based on the simulation and experimental results, we have devised a method to accurately locate the current path from MFM images with submicrometer uncertainty. The method was tested for different patterns of model conducting lines. It was shown to be a useful technique for fault location in IC failure analysis when current flows through the devices buried under overlayers and no topographic features are on the surface to provide clues about the positions of the devices.

Our main objective in this thesis is to investigate three methods: Principal Component Analysis, Vector Space Model, and Signal Analysis, to establish system behaviours of an electromechanical system based on its historical operation data. The system behaviours are constituted by an aggregate number of similar actions which can be represented as patterns or clusters. The results show that we are also able to observe normal behaviours by interpreting a high percentage of similar actions inside patterns or clusters. Any deviations from the established normal behaviours could be interpreted as abnormal which warrant further investigation with respect to fault pre-emption and detection.

The stator inter-turn faults can result in catastrophic failure of the electric machines leading to extended downtime of the equipment, increased cost of repair and heavy financial losses in the industries. In the recent trends, online fault diagnosis of the electric machines that arc employed in critical applications has been considered very important since frequent outage of the machines for the purpose of testing cannot he recommended. In this work. diagnostic tools have been developed to unambiguously detect the early stages of these limits in the salient-pole synchronous machines. both reluctance synchronous machine and synchronous machine with DC excitation. Motor current signature analysis. a very useful tool in the condition monitoring of electrical machines. has been primarily used for this purpose. This study mainly consists of development of theoretical background for the diagnostic schemes followed by the implementation of these schemes on both simulated and experimental machines. For this purpose. detailed mathematical models of the synchronous machines have been developed that can include stator inter-turn faults with desired fault severity. The developed models can also accommodate some structural asymmetries of the machines. These models have been instrumental in testing the proposed diagnostic schemes under ideal conditions. Also. reversible stator inter-turn faults have been carefully created in the experimental machines to test the feasibility of the diagnostic schemes under practical conditions. In order to ensure unambiguous fault detection. a detailed analysis has been performed under various possible abnormal operating conditions of the machines such as supply unbalance. time harmonics and internal asymmetries of the machines. Initially. certain drawbacks have been identified in a diagnostic scheme based on negative sequence quantities of the machine and critical improvements have been suggested to enhance its sensitivity. However, the modified method fails to detect faults involving one turn short. Hence a frequency domain approach has been considered to detect these faults. As a first step in this direction, it has been demonstrated that the triplen harmonics in the line current of synchronous machines cannot detect these faults unambiguously. Subsequently, owing to the stored magnetic energy in the machine after supply disconnection, it has been observed that the triplen harmonics in the terminal voltages of RSM can be useful for unambiguous detection of stator inter-turn faults. A new and very effective technique of online fault detection. based on the monitoring of some specific frequency components in the field current. has been developed for the synchronous machines with DC excitation. This scheme uses the structural asymmetries of the field winding. Similar results have also been realized using a rotor-mounted search-coil with very high sensitivity. In this work, an instrument has also been devised to implement fault diagnosis on machines using the computational capabilities of digital signal processors.

Thesis (M.S.)--University of Texas at El Paso, 2005. / Title from title screen. Vita. CD-ROM. Includes bibliographical references. Also available online.

Thesis (Ph. D.)--University of Missouri-Columbia, 1997. / Typescript. Vita. Includes bibliographical references (leaves 143-149). Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 1997. / Typescript. Vita. Includes bibliographical references (leaves 143-149). Also available on the Internet.