Sökning: "grid density"

Visar resultat 11 - 15 av 72 avhandlingar innehållade orden grid density.

  1. 11. On the robust stability analysis of VSC-HVDC systems

    Författare :Yujiao Song; Chalmers tekniska högskola; []
    Nyckelord :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;

    Sammanfattning : 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. LÄS MER

  3. 12. Topics in multifractal measures, nonparametrics and biostatistics

    Författare :Attila Frigyesi; Anestesiologi och intensivvård; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; confidence interval; mixed effects; Statistics; operations research; programming; actuarial mathematics; Statistik; operationsanalys; programmering; aktuariematematik; operational model of pharmacological agonism; concentration-response curves; dose-response curves; ventilation perfusion scintigraphy; V Q-scan; pulmonary embolism; automated method; box counting; correlation dimension; Hentschel-Procaccia dimension; Rényi dimension; generalized dimensions; fractal dimension estimation; dimension spectrum; multifractal measures; kernel density estimates; absolute continuity; singular distribution functions;

    Sammanfattning : This thesis consists of four papers. The first two papers, which comprise the main part of the thesis, deal with an unexpected connection between kernel density estimators and dimension spectra for multifractal measures. LÄS MER

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

    Författare :Yujiao Song; Chalmers tekniska högskola; []
    Nyckelord :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;

    Sammanfattning : 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. LÄS MER

  5. 14. Large Scale Solar Power Integration in Distribution Grids : PV Modelling, Voltage Support and Aggregation Studies

    Författare :Afshin Samadi; Lennart Söder; Olof Samuelsson; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Photovoltaic systems; PV system modelling; reactive power control; droop control; voltage sensitivity analysis; German Grid Codes; relative gain array RGA ; singular value decomposition SVD ; load modeling; system identification; Electrical Engineering; Elektro- och systemteknik;

    Sammanfattning : Long term supporting schemes for photovoltaic (PV) system installation have led to accommodating large numbers of PV systems within load pockets in distribution grids. High penetrations of PV systems can cause new technical challenges, such as voltage rise due to reverse power flow during light load and high PV generation conditions. LÄS MER

  7. 15. A Theoretical Study: The Connection between Stability of Single-Walled Carbon Nanotubes and Observed Products

    Författare :Daniel Hedman; Andreas Larsson; Sven Öberg; Krisztián Kordás; Luleå tekniska universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Single-walled carbon nanotubes; density functional theory; catalytic chemical vapor deposition; chirality-specific growth; stability; length; diameter; edge; chirality; Applied Physics; Tillämpad fysik;

    Sammanfattning : Over the past 20 years’ researchers have tried to utilize the remarkable properties of single-walled carbon nanotubes (SWCNTs) to create new high-tech materials and devices, such as strong light-weight composites, efficient electrical wires and super-fast transistors. But the mass production of these materials and devices are still hampered by the poor uniformity of the produced SWCNTs. LÄS MER