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Windpowered generators and high energy, low speed flywheels running in hybrid magnetic bearings


Energy storage devices of one kind or another, either as standby/emergency back-up or in parallel with power generators, have been the subject of worldwide research for many years. Flywheels amongst them possess many advantages over other systems such as batteries for energy density as well as in the environmental problems of disposal at the end of useful life.
With increasing confidence in the reliability of active magnetic bearings, effort has been directed in recent years at high speed cylinders (60,000 revs/min or more) which then need to be run in high vacuum. The novelty and objectives of the proposal here, on the other hand, are to run large diameter (1.0 to 1.5m dia), 100 kg to 150 kg flywheels, at speeds of the order of 5,000 revs/min in hybrid magnetic bearings employing combination of permanent magnet and active suspension.

Technical approach
The topics of research are, then, to investigate configurations in which bulk of the weight is taken up by the permanent magnet bearings and stability provided by one axial active bearing. The configurations will have very low electromagnetic losses, low aerodynamic losses even with partial vacuum and, through the use of a new transducerless active suspension system, provide extremely high safety and reliability.
All these are prerequisites for the application in parallel with wind turbines.
Problem areas not only concern the topics listed above but passive magnetic bearings are undamped and radial damping and stability of such flywheels will require simulation and experimental studies of different configurations.
The integral motor generator on the flywheel will also be a novel high efficiency machine.Its design(s) and interactions with the bearing system need to be characterised.The eventual rating for the wind turbine generators, with such flywheels, is to be in the range of 10-30 kW and the stored energy per flywheel 10 MJ.
Up to five flywheels operating in parallel with each turbine are therefore envisaged.The overall system control and power electronic conditioning converting inputs to fixed frequency, fixed voltage output and managing the load demands, needs a substantial simulation and prior research investigation.

Expected achievements and exploitations
It is proposed to set up a pilot installation with a 6 kW wind turbine with two flywheels operating in parallel to investigate the enhancement of effciency of such installations.
The concepts of this proposal are fully in harmony with the EU Green Paper Energy for the Future; Renewable Sources of Energy (20 Nov. 1936) and the more recent EU Conference on Renewable Sources of Energy (21 March 1997).
These are that development of renewable sources of energy can improve the quality oflife for millions of people who live in remote and scarcely populated areas, which is where wind and solar energy is often plentiful. It is exactly for such installations that energy storage devices are needed. Renewable energy sources in such areas are deemed to contribute to a balanced and sustainable economic development. Similar installations in developing countries will help to reduce CO2 emissions.

Funding Scheme

CSC - Cost-sharing contracts


University of Sussex

BN1 9QT Brighton - East Sussex
United Kingdom

Participants (4)

Elettrorava SpA
Via Don Sapino
10040 Savonera - Torino
NelCo Systems Ltd.
United Kingdom
Greenhill Crescent
WD1 8XU Watford
United Kingdom
Moorfield Industrial Estate, Troon Road
KA2 0BA Kilmarnock
University of Patras

26500 Patras