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Power converters for flywheel energy storage systems



This project addresses the requirement for short term energy storage with rapid charge/discharge cycling, typical of operation with renewable energy systems such as wind and wave. Previous work indicates that flywheel kinetic energy storage is a suitable technology for power smoothing in renewable energy systems, as well as in many industrial and transportation applications. The overall objective is to develop power converters and controllers for flywheel energy storage systems, to a level where they could be incorporated in demonstration renewable energy systems. Two drives will be developed; (i) a power electronic drive, by CEGELEC and (ii) a mechanical continuously variable transmission (CVT) drive, by P.I.V.; together with associated sensors; and controllers developed by University of Leicester and RAL. The drives will be integrated into flywheel energy storage systems and application tested at the RAL Wind Test Site.

Technical Approach

The effort will concentrate on the following main tasks :
1) Definition of the requirements for energy storage systems used for smoothing power fluctuations from renewable energy sources.
2) Development of power converter concepts for use in flywheel energy storage systems. Work on the drives and associated controllers will aim to provide systems with fast, precise torque and frequency control. 3) Prototype units of the two drives will be designed and constructed, and tests will be conducted to identify the key performance parameters. 4) The drives will be integrated with flywheels and electrical machines at the RAL Wind Test Site; (i) the mechanical CVT and controller, with a flywheel and synchronous motor/generator, and (ii) the power electronic drive and controller, with a flywheel and induction motor/generator. 5) The energy storage systems will be tested when operated with a wind turbine in both autonomous and grid connected applications, and the relative benefits of the two drive technologies will be assessed.

Expected Achievements and Exploitation

The outputs of this project will be :
1) development of requirements specifications for power electronic and mechanical CVT drives, for use in flywheel energy storage systems for short-term wind power smoothing
2) development of sensors, ratio and power control techniques for a state-of-the-art 30 kW mechanical CVT, capable of fast response when operating in torque and speed control modes
3) development of an advanced bi-directional 45 kW power electronic drive and controller, capable of fast active and reactive power control 4) integration of the drives into two pilot energy storage systems 5) assessment of the performance of the two energy storage systems 6) development of technology and designs which could be applied by manufacturers to provide power smoothing in renewable energy systems, and energy savings in many industrial and transportation applications

Funding Scheme

CSC - Cost-sharing contracts


OX11 0QX Didcot,harwell,chilton
United Kingdom

Participants (3)

Cegelec Industrial Controls Ltd
United Kingdom
West Avenue Kidsgrove
ST7 1TW Stoke-on-trent
P.I.V. Antrieb Werner Reimers GmbH & Co. KG
61352 Bad Homburg
University of Leicester
United Kingdom
University Road
LE1 7RH Leicester