Handbook of Energy Storage for Transmission or ... - W2agz.com

EPRI Proprietary Licensed Material
Description
History of Flywheel Systems
Flywheels rank among the earliest mechanical energy storage mechanisms discovered by
mankind. The principal was probably first applied in the potter’s wheel, a device used to
produce symmetrical ceramic containers. The millstone, a contrivance used to grind
grain into flour, is another form of flywheel.
Beginning in the early years of the Industrial Revolution, flywheels found their way into
various contrivances to smooth the delivery of mechanical power. In handlooms, for
instance, flywheels were used to store mechanical energy applied in pulses by the
operator. Flywheels allowed the development of more complex power machines such as
steam engines and internal combustion engines by enabling the delivery of constant,
continuous power from a pulsating power source. Flywheels continue to have a broad
variety of applications in mechanical systems.
Figure 1
Vertical Reciprocating Steam Engines Drive Westinghouse Flywheel Electric Generators In
Pittsburgh’s Railway Station, From 1902 Until 1950’s (Courtesy Of Smithsonian Institute)
Probably one of the first application of flywheels to large-scale electric power systems
was for smoothing the output of low-speed steam piston engine driving flywheel
generators, shown in Figure 1. Waterwheel generators also benefit from the flywheel
action of large salient-pole rotors. Heavy steel wheels are commonly integrated into
electric motor/ generator sets. In the event of pulsating or interrupted propulsion the
additional momentum of the flywheels smooths the output and helps to maintain desired
operating frequency. This direct flywheel contribution has improved quality and has
provided ride through capability during momentary, less than one second, interruptions.
The evolution of efficient inverters and rectifiers in the 1960s and early 1970s meant that
frequency could be controlled even when the generator was not spinning inside the
Flywheels Page 1