Search for dissertations about: "martin norgren"

Showing result 1 - 5 of 14 swedish dissertations containing the words martin norgren.

  1. 1. Online power transformer diagnostics using multiple modes of microwave radiation

    Author : Mariana Dalarsson; Martin Norgren; Sven Nordebo; KTH; []
    Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; inverse problem; multiple modes; power transformers;

    Abstract : In the present thesis, we propose and investigate a new approach to diagnose the effects of the various degradation mechanisms, including thermal degradation at hot spots, winding deformations due to the mechanical forces from short circuit currents, partial discharges due to local electric field surges, and increased moisture levels in the cellulose insulation due to decomposition, that affect electric power transformers during their normal operation in an electric power grid.Although the proposed diagnostics method can in principle be used to detect various degradation mechanisms mentioned above, we focus in the present thesis on mechanical deformations of transformer winding structures. READ MORE

  2. 2. Perturbation approach to reconstructions of boundary deformations in waveguide structures

    Author : Mariana Dalarsson; Martin Norgren; Sergei Tretyakov; KTH; []
    Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; inverse problems; waveguides; microwaves; perturbation theory; Electrical Engineering; Elektro- och systemteknik;

    Abstract : In this thesis we develop inverse scattering algorithms towards the ultimate goal of online diagnostic methods. The aim is to detect structural changes inside power transformers and other major power grid components, like generators, shunt reactors etc. READ MORE

  3. 3. Wide-angle scanning wide-band phased array antennas

    Author : Anders Ellgardt; Martin Norgren; Lars Josefsson; KTH; []
    Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Electrical engineering; Elektroteknik;

    Abstract : This thesis considers problems related to the design and the analysis of wide-angle scanning phased arrays. The goals of the thesis are the design and analysis of antenna elements suitable for wide-angle scanning array antennas, and the study of scan blindness effects and edge effects for this type of antennas. READ MORE

  4. 4. Periodic Structures with Higher Symmetries: Analysis and Applications

    Author : Fatemeh Ghasemifard; Martin Norgren; Oscar Quevedo-Teruel; Guido Valerio; Stefano Maci; KTH; []
    Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; periodic structures; higher symmetries; dispersion analysis; mode matching; generalized Floquet theorem; Electrical Engineering; Elektro- och systemteknik;

    Abstract : In this thesis, periodic structures with higher symmetries are studied. Their wave propagation characteristics are investigated and their potential applications are discussed. Higher-symmetric periodic structures are described with an additional geometrical operation beyond a translation operator. READ MORE

  5. 5. Remote contact-free reconstruction of currents in two-dimensional parallel conductors

    Author : Fatemeh Ghasemifard; Martin Norgren; Alessandro Formisano; KTH; []
    Keywords : Electrical Engineering; Elektro- och systemteknik;

    Abstract : In this thesis, the theory of the remote contact-free reconstruction of currents in two-dimensional parallel conductors is investigated. The motivation of this study is finding a complement technique to measurement transformers which are the well-established devices to measure currents in power transmission lines. READ MORE