23-06-2012, 10:40 AM
Flywheel Energy Storage System
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Introduction-
There are many ways that energy can be stored, such as, in chemical bonds (fuel), Capacitors, in the energy to separate ions (batteries), in gravitational potential energy (pumped hydro) or in kinetic energy (flywheels).
For example, here, In a flywheel, the inertia of a rotating mass is used to store energy.
Definition -
A flywheel stores energy in a rotating mass. Depending on the inertia and speed of the rotating mass, a given amount of kinetic energy is stored as rotational energy.
For Eg., In a potter’s wheel, the potter spins the wheel up from a stop by kicking it with his feet. Then when the potter molds the clay with his hands, he kicks the wheel occasionally to maintain the speed of rotation against the frictional forces that sap its energy and slow it down. Some of the friction is in the bearings of the wheel, and some is from working the clay. The purpose of the wheel is to keep the clay moving in a circular path so that it can be shaped into a vessel of cylindrical symmetry. The heavier the wheel the more uniform the velocity of rotation, and the more symmetrical the results.
Storage of Electrical Energy with Flywheel Technology -
In a modern flywheel for storage of electrical energy, there is usage of a rotating mass. Its purpose is to maintain the voltage of the attached lines at a constant value.
This rotating mass is made of metal or composite, and it is spun up by being part of an electrical motor.
To charge the flywheel with energy, pulses of electrical current are fed sequentially to fixed coils called the stator, and the magnetic fields from these currents exert forces on the rotor to spin it up.
An electrical motor and an electrical generator are very similar, and the same hardware can be used for both functions.
Whether the modern flywheel is being sped up, and thus storing energy, or whether it is being slowed down, and thus providing energy, is determined by the control system and the voltage of the system to which it is connected.
Load Flowing for Distributed Generation
In our power system, If there is a significant change in the load on the generator, such as when a large motor turns on or off, it is likely that two things will happen for an interval after the load change:
The voltage will sag or swell, and the efficiency of fuel consumption will drop.
If the load has increased, the voltage will sag.
If the load has decreased, the voltage will swell.
It is as if the generator literally had inertia, and a tendency to continue to do what it had been doing in terms of generation.
Flywheel Usage for stable power flow
Adding flywheel energy storage to a distributed generation system can provide four benefits:
It can stabilize voltage for power users.
Improve generator fuel efficiency
Reduce generator emissions and
Increase generator service life.
Flywheel technical considerations
Motor/Generator
High Voltage
No. of Poles
Power Electronics
Magnetic bearings
Vaccum Container