Matching Items (3)
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- All Subjects: MIMO
- All Subjects: Networks
- Creators: Ai, Weining
Description
Traditional approaches to modeling microgrids include the behavior of each inverter operating in a particular network configuration and at a particular operating point. Such models quickly become computationally intensive for large systems. Similarly, traditional approaches to control do not use advanced methodologies and suffer from poor performance and limited operating range. In this document a linear model is derived for an inverter connected to the Thevenin equivalent of a microgrid. This model is then compared to a nonlinear simulation model and analyzed using the open and closed loop systems in both the time and frequency domains. The modeling error is quantified with emphasis on its use for controller design purposes. Control design examples are given using a Glover McFarlane controller, gain sched- uled Glover McFarlane controller, and bumpless transfer controller which are compared to the standard droop control approach. These examples serve as a guide to illustrate the use of multi-variable modeling techniques in the context of robust controller design and show that gain scheduled MIMO control techniques can extend the operating range of a microgrid. A hardware implementation is used to compare constant gain droop controllers with Glover McFarlane controllers and shows a clear advantage of the Glover McFarlane approach.
ContributorsSteenis, Joel (Author) / Ayyanar, Raja (Thesis advisor) / Mittelmann, Hans (Committee member) / Tsakalis, Konstantinos (Committee member) / Tylavsky, Daniel (Committee member) / Arizona State University (Publisher)
Created2013
Description
As the number of devices with wireless capabilities and the proximity of these devices to each other increases, better ways to handle the interference they cause need to be explored. Also important is for these devices to keep up with the demand for data rates while not compromising on industry established expectations of power consumption and mobility. Current methods of distributing the spectrum among all participants are expected to not cope with the demand in a very near future. In this thesis, the effect of employing sophisticated multiple-input, multiple-output (MIMO) systems in this regard is explored. The efficacy of systems which can make intelligent decisions on the transmission mode usage and power allocation to these modes becomes relevant in the current scenario, where the need for performance far exceeds the cost expendable on hardware. The effect of adding multiple antennas at either ends will be examined, the capacity of such systems and of networks comprised of many such participants will be evaluated. Methods of simulating said networks, and ways to achieve better performance by making intelligent transmission decisions will be proposed. Finally, a way of access control closer to the physical layer (a 'statistical MAC') and a possible metric to be used for such a MAC is suggested.
ContributorsThontadarya, Niranjan (Author) / Bliss, Daniel W (Thesis advisor) / Berisha, Visar (Committee member) / Ying, Lei (Committee member) / Arizona State University (Publisher)
Created2014
Description
When does coercion succeed in international relations? Why do states resist coercion in some cases but concede in others? This dissertation adopts network analysis to investigate the network factors influencing the success and failure of economic and military coercion. The first chapter addresses the coercion target states’ information problem regarding how coercers would react to the targets’ resistances and concessions. By regarding resistances and concessions as network ties that can transmit information, it argues that past coercion outcomes endogenously influence targets’ current responses and coercion outcomes. Specifically, target states are more likely to concede to coercers who have been successful in gaining others’ compliance. Sender states are more likely to succeed in coercion when they had successful coercion in the past. The second chapter adds a condition to the first chapter’s argument. It argues that when being coerced by the same sender, a stronger sanction target’s compliance is likely to prompt a weaker target’s acquiescence, and that a weaker target’s resistance is likely to prompt a stronger target’s resistance. The third chapter explores how states’ positions in international security and economic networks influence the success and failure of military and trade coercion. States that occupy different network positions own different network power. I argue that when the coercion sender has relatively more network power than the target, the more likely coercion will be successful. I use interstate military alliances and arms transfer data to operationalize international security networks. International economic networks are operationalized by bilateral trade and regional trade agreements networks. Using military and trade coercion outcomes in the Military Compellent Threats (MCT) and the Threats and Imposition of Economic Sanctions (TIES) datasets as outcome variables, the statistical analysis partially supports my argument. Trade coercion is more likely to succeed when the sender has more network power. However, military coercion is less likely to succeed when the sender has more network power than the target.
ContributorsAi, Weining (Author) / Peterson, Timothy (Thesis advisor) / Thies, Cameron (Committee member) / Thomson, Henry (Committee member) / Chyzh, Olga (Committee member) / Arizona State University (Publisher)
Created2023