Search for dissertations about: "frequency stability"

Showing result 6 - 10 of 350 swedish dissertations containing the words frequency stability.

2. 6. Coordinated Frequency Control Between Interconnected AC/DC Systems

   Author : Danilo Obradovic; Mehrdad Ghandari; Robert Eriksson; Jonas Persson; KTH; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Power System Dynamics; Frequency Stability; Small Signal Stability; HVDC Supplementary Power Control; Electrical Engineering; Elektro- och systemteknik;

   Abstract : With ambitions of reducing the environmental pollution, power systems integrate larger shares of Renewable Energy Sources (RES) to phase out conventional thermal and nuclear generators. Since RES (such as wind and solar power) are connected to the grid through power electronics devices, they do not inherently contribute to system inertia. READ MORE

4. 7. Modeling of Modular Multilevel Converters for Stability Analysis

   Author : Luca Bessegato; Stefan Östlund; Staffan Norrga; Lennart Harnefors; Xiongfei Wang; KTH; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Modular multilevel converters MMCs ; stability; admittance; frequency-domain analysis; linearization techniques; current control; voltage control; ac ac converters; railway engineering.; Modulära multinivåomvandlare MMC ; stabilitet; admittans; frekvensanalys; linjäriseringsmetoder; strömreglering; spänningsreglering; ac ac omvandlare; järnvägsteknik.; Electrical Engineering; Elektro- och systemteknik;

   Abstract : Modular multilevel converters (MMCs) have recently become the state-of-the-art solution for various grid-connected applications, such as high-voltage direct current (HVDC) systems and flexible alternating current transmission systems (FACTS). Modularity, scalability, low power losses, and low harmonic distortion are the outstanding properties that make MMCs a key technology for a sustainable future. READ MORE

5. 8. Dynamic Models of Wind Turbines

   Author : Abram Perdana; Chalmers tekniska högskola; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; frequency stability; variable-speed; modeling; power system stability; validation; aggregated model; fixed-speed; voltage stability; wind turbine;

   Abstract : The impact of wind power generation in the power system is no longer negligible. Therefore, there is an urgent need for wind turbine models that are capable of accurately simulating the interaction between wind turbines or wind farms and the power system. READ MORE

6. 9. Wind Power - Added Value for Network Operation

   Author : Nayeem Ullah; Chalmers tekniska högskola; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; torsional oscillation; reactive power ancillary service; voltage stability; power system simulator.; STATCOM; non-minimum phase system; Variable speed wind turbine; frequency control; sensitivity analysis; transient stability; small-signal stability;

   Abstract : This dissertation deals with the investigation on different value added properties of variable speed wind turbines (VSWT) that stem from the flexible controllability of converter interfaced wind turbines (WT). Improvements in voltage and transient stability of a nearby grid, small-signal stability improvement on the power system, frequency control support for the network operation, as well as thetechnical and the economic issues related to the reactive power ancillary service provision, are among the issues covered. READ MORE

7. 10. On bone quality and implant stability measurements

   Author : Bertil Friberg; Göteborgs universitet; []
   Keywords : MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; early failures; titanium implants; jaw bone quality; jaw bone volume; cutting torque; implant stability; resonance frequency; one-stage surgery;

   Abstract : In conjuction with placement of oral implants, the jaw bone quality assessment is mainly based on quantitative radiographic measures and the subjective opinion of the performing surgeon. While the primary implant stability is discussed in terms of the pre-set motor torque and the subjective hand-felt perception during final tightening of implants, the secondary stability is defined as the absence of implant mobility. READ MORE