Search for dissertations about: "transformer"

Showing result 21 - 25 of 112 swedish dissertations containing the word transformer.

2. 21. Modeling of losses in power transformers from dc to the low kilohertz range

   Author : Julius Krah; Göran Engdahl; Roland Eriksson; Anthony Moses; KTH; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Electrical power technology; power transformer; losses; magnetic hysteresis; magnetic measurement systems; medium frequency; eddy currents; skin effect; thermal diffusion; Elkraftteknik; Electric power engineering; Elkraftteknik;

   Abstract : The development of HVDC converters, local generation and tractions systems increases the demand for power converters. While a lot of studies have been conducted on the power electronics, there are still open questions concerning the contained power transformer that operates at a few kilohertz. READ MORE

4. 22. Magnetizing Currents in Power Transformers : Measurements, Simulations, and Diagnostic Methods

   Author : Claes Carrander; Hans Edin; Göran Engdahl; Rajeev Thottappillil; Amr Adly; KTH; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Transformer core; diagnostics; three-phase; no-load; hysteresis; modeling; resonance; remanence; delta; Electrical Engineering; Elektro- och systemteknik;

   Abstract : This thesis demonstrates a method for transformer core diagnostics. The method uses the no-load current of the transformer as an indicator, and gives different characteristic signatures for different types of faults or defects. Using the no-load current for the diagnostic gives high sensitivity. READ MORE

5. 23. 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

6. 24. Modelling approaches for audio frequency power transformers

   Author : Julius Krah; KTH; []
   Keywords : power transformer; audio frequency; loss; hysteresis; eddy currents; skin effect. Leakage inductance;

   Abstract : The development of HVDC converters, local generation andtractions systems increases the demand for power converters.While a lot of studies have been conducted on the powerelectronics, there are still open questions concerning thecontained power transformer that operates at a few kilohertz. READ MORE

7. 25. Grid Connection of Permanent Magnet Generator Based Renewable Energy Systems

   Author : Senad Apelfröjd; Sandra Eriksson; Frans Dijkhuizen; Uppsala universitet; []
   Keywords : VAWT; H-rotor; Tap Transformer; Cascaded H-bridge Multi-Level; Renewable Energy; Wind power; Wave power; Marine Current Power; Engineering Science with specialization in Science of Electricity; Teknisk fysik med inriktning mot elektricitetslära;

   Abstract : Renewable energy is harnessed from continuously replenishing natural processes. Some commonly known are sunlight, water, wind, tides, geothermal heat and various forms of biomass. The focus on renewable energy has over the past few decades intensified greatly. READ MORE