Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2009. / Source: Dissertation Abstracts International, Volume: 70-06, Section: B, page: 3705. Advisers: Geir E. Dullerud; Mahesh Viswanathan. Includes bibliographical references (leaves 116-121) Available on microfilm from Pro Quest Information and Learning.

Thesis (Ph.D.)--Lehigh University, 2009. / Adviser: Xingkai Bao.

Thesis (Ph.D.)--Lehigh University, 2009. / Adviser: James C.M. Hwang.

Thesis (Ph.D.)--Lehigh University, 2009. / Adviser: Jing Tiffany Li.

Thesis (Ph.D.)--Lehigh University, 2009. / Adviser: Yujie Ding.

Thesis (Ph.D.)--Lehigh University, 2009. / Adviser: Rick S. Blum.

<p> Grid synchronization is a critical concern for proper control of energy transfer between the Distributed Power Generation Systems (DPGS) and the utility power grid. Nonlinear estimation techniques are proposed to track the voltage magnitude, phase angle, and frequency of the utility grid. Instead of directly analyzing in abc coordinate frame, the symmetrical component is employed to separate the positive, negative, and zero sequences in the transformed AlphaBeta stationary coordinate frame. By using the Fortescue's Transformations and Clarke's Transformation, the number of system state variables is reduced to five. The results show that our proposed nonlinear estimation technique is efficient in smart power system synchronization. The MATLAB simulation studies have been conducted to compare the performance of the Extended Kalman Filter (EKF), the Particle Filter (PF), and the Unscented Kalman Filter (UKF). Computer simulations have shown that the efficacy of our proposed nonlinear estimation methods. It also shows that the Unscented Kalman Filter, and the Particle Filter are better estimators, because voltage synchronization problem is nonlinear, and linearization process which the Extended Kalman Filter is based on is not very accurate. The number of particles in Particle Filter can be increased to improve the accuracy, but there exists a trade off between computational effort and estimation accuracy. In our research, considering the same amount of computational complexity, we calculate the Mean Square Error (MSE) to examine the performances of different nonlinear estimation approaches. By comparing the MSE of different estimators, we prove that the Unscented Kalman Filter shows the most accurate performance in voltage synchronization for three phase unbalanced voltage. Our results have shown the potential applications of the nonlinear estimation techniques in the future smart power grid synchronization. </p>

The basic requirements for insulation for overhead transmission lines also the problems of 'ageing' by 'weathering' and the effects of surface contamination are briefly surveyed. Correlation between the basic properties of polymeric insulating materials and their structure is considered. The causes of progressive degradation are discussed in some detail, with particular consideration of degradation by 'tracking' and 'erosion' and failure by flashover, in the presence of surface contamination. Test procedures which are used to assess the relative tracking resistance of insulating materials are C:escribed, with particular emphasis on the tests recommended by the International electrotechnical commission, which have been used by the candidate to assess a variety of resin bonded and elastomeric materials. The equipment used for these tests is described and the results of investigations to determine factors which affect the reproducibility of results are presented. Factors which should be specified in the test recommendations are summarized in Section 9.1. The current v voltage characteristics of short, current limited discharges in air have been investigated and used to estimate the rete of power dissipation by single discharge across dry bands. If the rate of heat dissipation were uniform along the length of the discharges, the temperature rise at the surface of the insulation would be insufficient to cause thermal degradation, unless discharges recur at the sane site for several seconds. However, the temperature rise would beg greater, if heating were concentrated at the 'roots of the discharge. This is indicated by a marked polarity effect found when inclined plane tests were made with half wave rectified voltage. A limited number of tests on polyester matt glass mouldings showed that doubling the electrode spacing increased the voltage to cause track initiation and failure by 1.55 times. This is consistent with failure by thermal degradation when account is taken of the greater flow of contaminant at the higher test voltage.

No description available.

A compatibility graph-based, general area router for integrated circuit (IC) designs is presented. The highly flexible constraint system allows a number of modern and mixed-signal routing requirements to be handled, even for a large number of nets. The IC router can efficiently construct near-minimal Steiner trees for multi-terminal nets in both classical rectilinear, or Manhattan, geometry as well as octilinear geometries. These Steiner trees can be constructed around blockages, and in the presence of obstacles such as other nets. A method for routing trees through weighted areas is also introduced. The routing system can predict congested routing areas before routing is performed, and appropriately weight congested areas in order to reduce net congestion. Finally, a fast crosstalk violation checker can run alongside the routing engine. Each portion of the router is bounded by O(n log(n)) runtime, or less, making the entire routing process bounded by the same runtime. The system thus scales well to handle a very large number of exact routes in a fully mixed-signal aware engine, in either rectilinear or newly-introduced octilinear geometries.