Search for dissertations about: "Nyquist stability analysis"

Found 5 swedish dissertations containing the words Nyquist stability analysis.

2. 1. 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

4. 2. 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

5. 3. 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

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. Modelling and control of a line-commutated HVDC transmission system interacting with a VSC STATCOM

   Author : Paulo Fischer de Toledo; Hans-Peter Nee; Gustaf Ohlsson; KTH; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Keywords : HVDC transmission; LCC – Line-commutated Current-source Converter; STATCOM; VSC – Voltage Source Converter; Space-Vector complex vector ; transfer-function; frequency-domain analysis; Electrical engineering; electronics and photonics; Elektroteknik; elektronik och fotonik;

   Abstract : The interaction of an HVDC converter with the connected power system is of complex nature. An accurate model of the converter is required to study these interactions. The use of analytical small-signal converter models provides useful insight and understanding of the interaction of the HVDC system and the connected system components. READ MORE