Search for dissertations about: "Nyquist stability criterion"

Showing result 1 - 5 of 7 swedish dissertations containing the words Nyquist stability criterion.

2. 1. Nyquist Stability Analysis of a VSC-HVDC System with a Distributed Parameter DC-cable Model

   Author : Yujiao Song; Chalmers tekniska högskola; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Electric power transmission; Nyquist stability analysis; VSC-HVDC system; Distributed parameter cable model; Small gain theorem.; Weak AC-grid;

   Abstract : Voltage source converter based high voltage direct current (VSC-HVDC) transmission systems have now been in operation since 1997 as it is a reliable and flexible method of power transmission. This thesis focuses on small signal dynamics of such systems, emphasizing stability properties. READ MORE

4. 2. On the robust stability analysis of VSC-HVDC systems

   Author : Yujiao Song; Chalmers tekniska högskola; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; symbolic eigenvalue expressions; distributed parameter cable model; AC-grid interaction; VSC-HVDC system; passivity theorem; small gain theorem; Nyquist stability analysis;

   Abstract : This thesis focuses on small signal stability analysis of VSC-HVDC systems, emphasizing the system stability robustness with regard to the connected AC-grid and the distributed parameter DC-grid model respectively. In addition, for strong AC-grid connected systems, analytical eigenvalue expressions are provided to investigate the impact of physical or control parameters on the system stability for both two-terminal and multi-terminal VSC-HVDC systems. READ MORE

5. 3. Chatter stability of turning and milling with process damping

   Author : Mahdi Eynian; Yusuf Altintas; Canada The University of British Columbia The Faculty of Graduate Studies (Mechanical Engineering); []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY;

   Abstract : The prediction of chatter instability in machining steel and thermal-resistant alloys at low ‎cutting speeds has been difficult due to unknown process damping contributed by the ‎contact mechanism between tool flank and wavy surface finish. This thesis presents ‎modeling and measurement of process damping coefficients, and the prediction of chatter ‎stability limits for turning and milling operations at low cutting speeds. READ MORE

6. 4. Subsynchronous Resonance in Doubly Fed Induction Generator based Wind farms

   Author : Selam Chernet; Chalmers tekniska högskola; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; generalized Nyquist criterion GNC .; Passivity; doubly-fed induction generator DFIG ; subsynchronous controller interaction SSCI ; Wind power; Impedance-based analysis; induction generator effect IGE ; subsynchronous resonance SSR ;

   Abstract : The objective of this thesis is to investigate the risk for instabilities due to subsynchronous resonance (SSR) conditions in large wind farms connected to series-compensated transmission lines. In particular, the focus is on doubly-fed induction generator (DFIG) based wind farms. READ MORE

7. 5. Modeling and Stability Analysis of Rate and Power Control Systems in Wireless Communication Networks

   Author : Anders Möller; Xiaoming Hu; John Baillieul; KTH; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES;

   Abstract : Wireless data traffic in cellular networks is currently undergoing a strong global expansion and the demand for high and reliable data throughput increases. Capacity is, however, a limited resource, and in radio resource management a trade-off has to be made between the congestion level, related to cell coverage and interference levels, and the Quality of Service (QoS) or data rates of the users. READ MORE