Sökning: "transformer"

Visar resultat 26 - 30 av 116 avhandlingar innehållade ordet transformer.

1. 26. Effect of Dielectric and Magnetic Material Characteristics on Frequency Response of Power Transformers

   Författare :Nilanga Abeywickrama; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; frequency response analysis; dielectric insulation; Complex permeability; core magnetization; finite element method; transformer diagnosis.; high frequency modelling; magnetic viscosity; silicon steel;

   Sammanfattning : Frequency response analysis (FRA) technique has become increasingly popular for the assessment of mechanicalintegrity in power transformers. This method is based on the fact that the shape of the frequency response at higher frequencies is uniquely determined by the geometrical construction of the transformer. LÄS MER

3. 27. Diagnostics of Oil-Impregnated Paper Insulation Systems by Utilizing Lightning and Switching Transients

   Författare :Roya Nikjoo; Hans Edin; Christer Törnkvist; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Capacitance; Dielectric Response; Loss tangent; Moisture content; Oil - impregnated paper; Temperature; Transformer Bushing; Transients;

   Sammanfattning : Development of the power gridtowards a more reliable and smarter system requires frequent on-line monitoring of the power components. Power transformers and their bushings are particularly important components in a power transmission system and their insulation degradation may lead to catastrophic failures. LÄS MER

4. 28. Dielectric Response and Partial Discharge Diagnostics of Insulation Systems by Utilizing High Voltage Impulses

   Författare :Roya Nikjoo; Hans Edin; Andrea Cavallini; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Dielectric Response; Transients; Transformer bushing; Oil-impregnated paper; Moisture content; Partial discharge; Surface PD; Cavity PD; Superimposed impulse; Nanoparticles; Electrical Engineering; Elektro- och systemteknik;

   Sammanfattning : In this thesis, power system transients are considered as an opportunity for development of on-line diagnostics of power components and specifically the insulation systems of power transformers and bushings.A new technique for on-line dielectric response measurement of power transformer bushings is proposed which utilizes natural transients in the power system, such as lightning and switching surges, as stimuli. LÄS MER

5. 29. Automating Power Quality Analysis

   Författare :Emmanouil Styvaktakis; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; pattern classification; expert systems; induction motors; power system transients; voltage dips; power system faults; power quality; Kalman filtering; power system monitoring; transformer saturation; short time Fourier transform;

   Sammanfattning : The increased requirements on supervision, control, and performance in modern power systems make power quality monitoring a common practise for utilities. Large databases are created and automatic processing of the data is required for fast and effective use of the available information. LÄS MER

7. 30. DC-DC Converters - Dynamic Model Design and Experimental Verification

   Författare :Bengt Johansson; Industriell elektroteknik och automation; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; robotics; buck; dc-dc converter; modeling; audio susceptibility; current-mode control; load current; gain scheduling; current transformer; experimental verification; Electronics and Electrical technology; Automation; Elektronik och elektroteknik; Elektroteknik; Electrical engineering; reglerteknik; robotteknik; Automatiska system; control engineering;

   Sammanfattning : To obtain high performance control of a dc-dc converter, a good model of the converter is needed. The load usually affects the dynamics and one way to take this into consideration is to regard the load as a part of the converter. The load is often the most variable part of this system. LÄS MER