Sökning: "transformer"
Visar resultat 21 - 25 av 116 avhandlingar innehållade ordet transformer.
21. Modeling of losses in power transformers from dc to the low kilohertz range
Sammanfattning : 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. LÄS MER
22. Magnetizing Currents in Power Transformers : Measurements, Simulations, and Diagnostic Methods
Sammanfattning : 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. LÄS MER
23. Online power transformer diagnostics using multiple modes of microwave radiation
Sammanfattning : 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. LÄS MER
24. Modelling approaches for audio frequency power transformers
Sammanfattning : 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. LÄS MER
25. Grid Connection of Permanent Magnet Generator Based Renewable Energy Systems
Sammanfattning : 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. LÄS MER