Cambridge IEA Presentation Archie Campbell
CONTENTS1) Converteam superconducting generators.2) Tim Coomb’s flux pump.3) AC Losses in 2G magnets.
Converteam was Alsthom and before that GEC. It has three major projects. 1) Wind Generator 2) Hydrogenerator 3) Wave Generator The next few slides were copied from Clive Lewis’s presentation London 2007.
Summary Synchronous generator - 8 MW at 12 rpm, ~100 tonnes HTS DC field winding in rotor Normal temperature armature winding in stator Variable speed, low frequency (1.6 Hz) connected to grid though converter Airgap winding machine No iron cores in rotor poles No iron teeth in stator
Project Summary Part funded by DTI (now BERR) Technology Programme Partners Converteam - Lead, generator design and manufacture A S Scientific - Cryogenic systems University of Warwick - composite materials research and volume manufacturing HTS coils manufactured by Trithor Phase 1 (completed) Conceptual design of direct drive HTS generator – 8 MW, 12 rpm, 100 tonnes Economic and market analysis Phase 2 (in progress - completion in 2009) Design, manufacture and test of scaled generator – 500 kW, 30 rpm, 25 tonnes Detailed design and costing of full size generator
HYDROGENIE Project Part funded by EU Design + manufacture of a 1.7 MW Hydrogenerator to be installed and operated in a commercial power station Partners Converteam (UK) - Lead and generator design Trithor (Germany) - HTS Coils E.On (Germany) - Power station owner and operator Stirling (NL) - Maintenance free cryocooler KEMA (NL) - System integration study Vector fields (UK) - Electromagnetic design software SUT (Poland) - HTS Coil test and validation
Summary Synchronous generator 1.7 MW, 0.95 PF at 214 rpm HTS DC Field winding on rotor Normal temperature stator 50 Hz - directly synchronised to grid Magnetic iron cored machine Iron pole bodies and pole shoes on rotor contained within a single vacuum vessel HTS Coils supported on cold stainless steel structure, each insulated with superinsulation Conventional stator with iron teeth
Ocean Power A large US company making arrays of buoys which extract energy from the vertical motion of the waves. Converteam are doing a design study with a superconducting coil.
SUMMARY,May 2009 Wind generator Building model, 500kW, 25 tons, 30 rpm, DTI funded built and tested by 2010 Zenergy Subcontractor. Also doing a full scale10MW design study. Hydro- generator for Germany., Zenergy partner. 1.7MW, 214 rpm 28 pole, being built and tested. 2.5m diameter magnet. Completion this year Ocean Power Wave Generator Linear generator with superconducting rotor, design study, no hardware
Tim Coombs’s Flux Pump A moving temperature step creates a moving magnetisation step which pushes flux into the bulk YBCO. When flux creep is included modelling shows that fields can be generated greater than the applied field. Experiments are in progress.
Magnetisation • Four possible known methods: • Cool in field • Zero field cool then field applied slowly • Pulse magnetisation • Flux pumping • Any of these methods could be used to magnetise the superconductor. 3 Tesla @ 77 K 17 Tesla @ 29 K
Left side is J Right side switches continuously from plus to minus Jc according to the sign of A and therefore E. (The Bean Model) This can be solved with FE
This can be extended to 2 and 3D by including a scalar potential V If in addition A=0 then E=2V so that that V can be expected to be due to electrostatic charges, although in principle it can have any arbitrary component such that 2V=0.
X-Z X-Y 3D Critical state. Field applied parllel to face of puck Y-Z
AC Losses and Critical Current of 2G Coils First FE , FlexPDE
Pancake Coil >200 tapes. In applied field can be treated as a slab with mean Jc.
We cannot impose the condition that each tape carries the same current. Use a model by Clem
The geometry forces the field between the tapes to be parallel, J is uniform in the unpenetrated region. Each wire carries the same current The width c is adjusted to minimise the normal field. We use Kim model for Jc(B)
The critical state boundary curves inward, instead of outward as in a solid wire.
Field Lines Bz at various heights
J contours at low I and at Ic Ic=803 A (Superpower 2G tapes, Kim model, our method) Ic=1324 A (Fill with Jc consistent with local field) Ic=643 A (Uniform Jc consistent with max of Bz)