Sökning: "field winding short circuit"

Hittade 5 avhandlingar innehållade orden field winding short circuit.

1. 1. Run-Up Transient Analysis for Salient Pole Wound Field Synchronous Motors : Field winding and power electronics implications for a smoother and cooler asynchronous start

   Författare :Roberto Felicetti; Urban Lundin; Andreas Binder; Uppsala universitet; []
   Nyckelord :apparent resistance; cable modeling; current control; transmission line model; eddy currents; field winding; frequency analysis response; Fourier Transform; impedance mismatch; main inductance; overvoltage; parasitic capacitance; partial discharge; quality factor; ringing; slew rate; stray inductance; voltage gradient; winding resonance frequency; asynchronous start; run-up; torque ripple; reluctance torque; Engineering Science with specialization in Science of Electricity; Teknisk fysik med inriktning mot elektricitetslära;

   Sammanfattning : Salient Pole Wound Field Synchronous Machines have better efficiency at full load than asynchronous machines of the same capability. Moreover, where asynchronous machines need inherently to draw a magnetizing current from the grid, Salient Pole Wound Field Synchronous Machines can work efficiently at unity power factor. LÄS MER

3. 2. Measurement and modelling of unbalanced magnetic pull in hydropower generators

   Författare :Mattias Wallin; Urban Lundin; Antero Arkkio; Uppsala universitet; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Damper winding; eddy currents; field winding short circuit; finite element method; hydropower generator; parallel circuits; rotor eccentricity; salient poles; synchronous generators; synchronous machines; UMP; unbalanced magnetic pull.; Engineering Science with specialization in Science of Electricity; Teknisk fysik med inriktning mot elektricitetslära;

   Sammanfattning : Hydropower research is often perceived to be an old and exhausted field of study but with ageing equipment and the need for more intermittent operation caused by an increased share of other renewable energy sources new challenges lie ahead.The main focus of this dissertation are the electromagnetic forces resulting from nonuniform air gap flux, whether it be caused by rotor eccentricity or a faulty field winding. LÄS MER

4. 3. Hydropower generator and power system interaction

   Författare :Johan Bladh; Urban Lundin; Rafael Escarela-Perez; Uppsala universitet; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Amortisseur windings; applied voltage test; automatic voltage regulators; damper windings; damping torque; empirical modelling; equivalent circuits; excitation control; finite element method; hydropower generators; power system restoration; power system stability; synchronous machines; self excitation; shaft torque amplification; short circuit test; single machine infinite bus; slip test; standstill frequency response test; subsynchronous oscillations; synchronising torque; synchronous generators; torsional interaction.; Engineering Science with specialization in Science of Electricity; Teknisk fysik med inriktning mot elektricitetslära;

   Sammanfattning : After decades of routine operation, the hydropower industry faces new challenges. Large-scale integration of other renewable sources of generation in the power system accentuates the role of hydropower as a regulating resource. LÄS MER

5. 4. Online power transformer diagnostics using multiple modes of microwave radiation

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

   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

7. 5. Modeling and Analysis of PMSM with Turn-To-Turn Fault

   Författare :Joachim Härsjö; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; electromagnetic forces; vibration.; inter-turn; fault; fault detection; turn-to-turn fault; Permanent magnet synchronous machine PMSM modeling;

   Sammanfattning : Thanks to its high-torque density and high efficiency, the Permanent Magnet Synchronous Machine (PMSM) is today used in a vast range of applications, spanning from automotive to wind. Since in a PMSM the excitation field is provided by a permanent magnet instead of a coil, this machine does not have a rotor circuit and thereby the risk for electrical failures can be isolated on the stator circuit. LÄS MER