2011 International Conference on Alternative Energy in Developing Countries and Emerging Economies
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amount of energy storage depends on the mass, flywheel
shape, and rotational speed of the rotor. In motoring mode
flywheel is speeded up to store rotational energy and is slowed
down to release energy in generating mode by a motor-
generator system.
Fig. 1. Flywheel energy storage system.
The amount of energy stored and released E, is calculated by
means of the equation
E= ½ Iω
2
………... …………………
. (i)
Where,
I= Moment of Inertia of the Flywheel and
ω= Rotational speed of the Flywheel.
III. S
YSTEM
S
IZING AND
S
IMULATION
Sizing of a flywheel energy storage system is very
important. A proper size of the storage system is necessary for
balancing the load and the supply. Maximum ramp up of load
within a shortest period should be taken into account while
sizing a flywheel energy storage system. Dimension, materials
of the flywheel, maximum rotational speeds etc. are also the
considering factors to design proper size flywheel storage.
Detailed calculation should be carried out to find out an
optimum size. Some software can automatically do the same
to find out the required size of a system according to the
nature of l
oad data and source data. We used ‘HOMER’
software to find out the suitable size of our proposed flywheel
energy storage system. From the system sizing it was found
that at least one 25 kWh rated capacity flywheel is necessary
for Ramea hybrid power system for energy back up. Smart
Energy (SE25) flywheel from Beacon Power Corporation is
used for the system sizing which has highly cyclic capability,
smart grid attributes, 20-years design life and sustainable
technology. For simulations using HOMER we have done two
separate simulations. One is without the FESS and other one is
with the FESS. For System dynamics Matlab/Simulink is
used. Simulations & results are presented in the following
section.
IV. S
IMULATION
U
SING
H
OMER
Fig. 2. Ramea hybrid power system block diagram.
Fig. 4. Ramea load data.
Fig. 3. Ramea wind resource data.
