Separation of multiple time delays using new spectral estimation schemes

Includes bibliographical references.The problem of estimating multiple time delays in presence of colored noise is considered in this paper. This problem is first converted to a high-resolution frequency estimation problem. Then, the sample lagged covariance matrices of the resulting signal are computed and studied in terms of their eigenstructure. These matrices are shown to be as effective in extracting bases for the signal and noise subspaces as the standard autocorrelation matrix, which is normally used in MUSIC and the pencil-based methods. Frequency estimators are then derived using these subspaces. The effectiveness of the method is demonstrated on two examples: a standard frequency estimation problem in presence of colored noise and a real-world problem that involves separation of multiple specular components from the acoustic backscattered from an underwater target.This work was supported by the Office of Naval Research (ONR 321TS). The Technical Agent was Coastal Systems Station, Panama City, FL

A novel system impedance measurement for power system analysis and improvement in power quality

This thesis presents an investigation of on-line supply impedance measurement. Network impedance values are invaluable for power system modelling and simulation. Without knowledge of a network structure and the impedances that make up that structure it is impossible to simulate or predict harmonic propagation within a plant. If the impedance structure for a plant is known then it may be possible to alleviate voltage distortion problems by simply redistributing sensitive loads to points of low harmonic distortion. Alternatively distorting loads may be repositioned thus removing the need for additional filters or compensation equipment. The supply impedance, in particular, is of interest. At a simple level it is important for wiring, fuse and circuit breaker calculations. It is also important when designing filters for power factor correction or harmonic attenuation. Two novel on-line impedance measurement techniques are presented. Both techniques apply a small disturbance to a power network, using measurements of the subsequent transients it is possible to identify the system impedance at the point of measurement. These techniques are implemented both in simulation and experimentally. Excellent identification was possible for linear impedance networks. The performance of the techniques was also investigated in the presence of various non-linear loads. Limitations to both approaches are identified. An active shunt filter was designed and constructed for this work. Experimental impedance measurement was undertaken using this hardware. It was therefore possible to demonstrate the possibility of impedance measurement using an existing active shunt filter and during its normal operation. Finally experimental measurement data was used to demonstrate the operation of the active shunt filter using reference currents determined from supply voltage and supply impedance

A novel system impedance measurement for power system analysis and improvement in power quality

This thesis presents an investigation of on-line supply impedance measurement. Network impedance values are invaluable for power system modelling and simulation. Without knowledge of a network structure and the impedances that make up that structure it is impossible to simulate or predict harmonic propagation within a plant. If the impedance structure for a plant is known then it may be possible to alleviate voltage distortion problems by simply redistributing sensitive loads to points of low harmonic distortion. Alternatively distorting loads may be repositioned thus removing the need for additional filters or compensation equipment. The supply impedance, in particular, is of interest. At a simple level it is important for wiring, fuse and circuit breaker calculations. It is also important when designing filters for power factor correction or harmonic attenuation. Two novel on-line impedance measurement techniques are presented. Both techniques apply a small disturbance to a power network, using measurements of the subsequent transients it is possible to identify the system impedance at the point of measurement. These techniques are implemented both in simulation and experimentally. Excellent identification was possible for linear impedance networks. The performance of the techniques was also investigated in the presence of various non-linear loads. Limitations to both approaches are identified. An active shunt filter was designed and constructed for this work. Experimental impedance measurement was undertaken using this hardware. It was therefore possible to demonstrate the possibility of impedance measurement using an existing active shunt filter and during its normal operation. Finally experimental measurement data was used to demonstrate the operation of the active shunt filter using reference currents determined from supply voltage and supply impedance