Document Type

Theses, Masters


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The slow move from a fossil-fuel powered society to a renewable-energy powered society is creating and will continue to create a demand for good energy storage techniques. The electromechanical battery (EMB), comprising a flywheel energy storage system with electrical input and output, is one of the many candidate technologies. Two different EMB types are evaluated in this present project. The first is a ring (or annular) flywheel to be constructed using fibre composite materials and to rotate at high speed in a vacuum. Energy is to be imported and exported electromagnetically based on linear electrical machine principles. Confinement of the annulus is to be performed electrodynamically using superconductors. The basic mechanical and electr4omagnetic considerations are summarised and the prospects of this composite annular flywheel are considered for different applications. The second EMB evaluated is a more conventional system and is aimed at the standby power supply market. This EMB principally comprises the following off-the-shelf components- an induction machine, capacitors and a fly-wheel. The system is permanently connected on line, with the induction machine operating in its motoring mode so as to overcome rotational losses. In the event of a mains failure, the induction machine reverts to being a self excited induction generator and extracts energy from the flywheel to power the load. Obviously, the extraction of energy from the flywheel causes deceleration and frequency and voltage reduction. These effects are examined in detail, and implications for this particular EMB are assessed.