Introduction:
Electricity, the base of modern civilization, is produced by electric generators, which are devices converting mechanical energy into electric energy [1-2]. As the need for energy is increasing, while the reserves of fossil fuels are dwindling, renewable energy sources gain importance. The renewable energy can be obtained using solar, geothermal, or wind turbine technologies. Significant research effort has been made in those areas.
In recent years, wind energy has become the fastest growing electrical power source and expected to be widely adopted in the future as wind energy is the most renewable and green energy source in natural resources. The fact is that the cost of energy supplied by wind turbines are continuously …show more content…
The meachanical energy of wind energy is captured by the wind turbin that have aircraft blads to transmite this power to electrical power by using different types of electrical generators.
Fig(1) shows the construction of wind energy system the wind turbines connedted to the electrical generator throgth the mechanical system( gearbox), as the electrical generator produce AC voltage source the diode bridge convert it to DC source. There are some energy stored in battery bank before the rest power inverted again from DC to AC source.
Fig(1)
The power energy available in wind can be expressed in mathematical equation as:
= Air density (approx.1.225 kg/m3 at sea level) = Velocity of wind (m/s) = Area through which the wind passes normally (m2)
This cubic relationship mean the power availability is extremely sensitive to wind speed
The power extracted from wind energy is just a fraction of this equation. Actualy the extracted power can be givin …show more content…
Increase in the temperature reduces both the remanence and coercive force of the magnet by specified factors which are dependent on the type of the magnet material. Generally the loss due to temperature effects can be classified onto three categories; reversible, irreversible and irrecoverable. Reversible losses are defined as changes in the B-H characteristics due to the variation of the temperature over a limited range where the remanence and coercivity are linearly related to the temperature. Irreversible losses are defined as the partial demagnetization of the magnet caused by exposure to temperature higher than the maximum operating temperature. Therefore, stabilization of the magnet slightly above this limit is very important to prevent irreversible losses. However these losses can be recovered by remagnetization of the magnet if they have not been exposed to temperatures above the Curie temperature, which is defined as the temperature at which the magnetization will drop to zero, and the magnet can be remagnetized to its original state assuming no metallurgical changes has occurred. The irrecoverable losses are caused by exposure of the magnet to very high temperature above the Curie temperature for a long time which causes metallurgical changes in the material and cannot be recovered by any
Electricity, the base of modern civilization, is produced by electric generators, which are devices converting mechanical energy into electric energy [1-2]. As the need for energy is increasing, while the reserves of fossil fuels are dwindling, renewable energy sources gain importance. The renewable energy can be obtained using solar, geothermal, or wind turbine technologies. Significant research effort has been made in those areas.
In recent years, wind energy has become the fastest growing electrical power source and expected to be widely adopted in the future as wind energy is the most renewable and green energy source in natural resources. The fact is that the cost of energy supplied by wind turbines are continuously …show more content…
The meachanical energy of wind energy is captured by the wind turbin that have aircraft blads to transmite this power to electrical power by using different types of electrical generators.
Fig(1) shows the construction of wind energy system the wind turbines connedted to the electrical generator throgth the mechanical system( gearbox), as the electrical generator produce AC voltage source the diode bridge convert it to DC source. There are some energy stored in battery bank before the rest power inverted again from DC to AC source.
Fig(1)
The power energy available in wind can be expressed in mathematical equation as:
= Air density (approx.1.225 kg/m3 at sea level) = Velocity of wind (m/s) = Area through which the wind passes normally (m2)
This cubic relationship mean the power availability is extremely sensitive to wind speed
The power extracted from wind energy is just a fraction of this equation. Actualy the extracted power can be givin …show more content…
Increase in the temperature reduces both the remanence and coercive force of the magnet by specified factors which are dependent on the type of the magnet material. Generally the loss due to temperature effects can be classified onto three categories; reversible, irreversible and irrecoverable. Reversible losses are defined as changes in the B-H characteristics due to the variation of the temperature over a limited range where the remanence and coercivity are linearly related to the temperature. Irreversible losses are defined as the partial demagnetization of the magnet caused by exposure to temperature higher than the maximum operating temperature. Therefore, stabilization of the magnet slightly above this limit is very important to prevent irreversible losses. However these losses can be recovered by remagnetization of the magnet if they have not been exposed to temperatures above the Curie temperature, which is defined as the temperature at which the magnetization will drop to zero, and the magnet can be remagnetized to its original state assuming no metallurgical changes has occurred. The irrecoverable losses are caused by exposure of the magnet to very high temperature above the Curie temperature for a long time which causes metallurgical changes in the material and cannot be recovered by any