INDUCTION GENERATOR FOR WIND POWER GENERATION

OUTLINES Introduction What is induction generator ? History Wind turbines Terminologies used Working Wind power developed by wind turbine Controlling Why induction generator is used ? Advantages and Disadvantages of wind energy Application of wind energy Conclusion References

INTRODUCTION * Wind turbines convert the kinetic energy present in the wind into mechanical energy by means of producing torque . * In the present scenario ,most wind turbine manufactures now equip power generating units by induction generators. * They are operated either at fixed speed or variable speed. * Generators driven by fixed speed turbines can directly be connected to grid. * Variable speed generators need a power electronic converter interface for interconnection with the grid. * Variable speed generation is preferred over fixed speed generation.

WHAT IS INDUCTION GENERATOR * The motor which runs in the principle of induction rather than conduction is called as induction motor. * If an induction motor is driven at a speed greater than synchronous speed by an external prime mover, the direction of its inducted torque will reverse and it will act as a generator. This is induction generator. As the torque applied to the shaft by prime mover increases, the amount of power produced by induction generator increases. * Induction generator is widely used in windmills.

FIGURES OF INDUCTION GENERATOR

HISTORY * This is the first automatically operating wind turbine for electricity generation. *It was built by Charles F. Brush in 1887-1888 , which was supplied 12 kW power to 350 incandescent lights. * Its rotor was 17 meters in diameter.

WIND TURBINES * Wind turbines convert wind energy to electricity for distribution. * Aerodynamic modeling is used to determine the optimum tower height , control systems , number of blades and blade shape. * Wind turbines are generally classified depending on their axis of rotation as - 1- Horizontal axis type 2-Vertical axis type * The horizontal axis types generally have better performance. * A quantitative measure of the wind power available at any location is called wind power density(WPD). * Commercial wind farms generally produce a wind power density of 400 watts/square meter .

HORIZONTAL AXIS WIND TURBINE VERTICAL AXIS WIND TURBINE AALBORG-TURBINE DARRIEUS-WINDMILL

TERMINOLOGIES USED *ROTOR BLADES - The blades are the sails of the system , when the wind forces the blades to move , it has transferred some of its energy to the rotor . *SHAFT SYSTEM – The wind turbine shaft is connected to the centre of the rotor, when the rotor spins the shaft spins as well. Thus rotor transfers its mechanical rotational energy to the shaft . *GEAR BOX- It turns the slow rotation of the blades into a quicker rotation that is more suitable to drive the induction generator .

WORKING * Turbine convert wind energy into rotary mechanical energy. *A mechanical interface, transmits the energy to an electrical generator. *The output of this generator is connected to the load or system grid . *The controller senses the wind direction , wind speed , power output of the generator . *Several schemes for electrical generation have been developed , such as, 1- Constant speed generation system . 2-Variable speed generating system . *At constant speed generation system suffer from a number of drawbacks hence variable generation system is preferred .

WIND POWER DEVELOPED BY THE WIND TURBINE IS GIVEN BY : P=(Cp AρV^3)/2 Where Cp: Power coefficient A: Area swept by rotor blades ρ: Air density V: Velocity of wind

CONTROLLING INDUCTION GENERATOR CONTROL - * Cage rotor induction generators can be made to operate over a wider speed range by pole changing . * A wound rotor induction generator can be controlled by varying the slip energy of the rotor circuit using following methods – a)Rotor resistance control , b)cascading * A bank of capacitors connected to the terminals can be used . 2) TRANSMISSION CONTROL - * The transmission control can be happened by using silicon controlled rectifier device .

WHY INDUCTION GENERATOR IS USED ? It is Simple and vigorous in construction . It Can run independently . It is not expensive . It has inherent overload protection . It requires very low maintenance .

ADVANTAGES OF WIND ENERGY * Wind power system is a renewable source of energy . * Wind power systems are non-polluting . * Wind energy systems avoid fuel provision . DISADVANTAGES OF WIND ENERGY *The available of wind energy is fluctuating in nature so wind energy needs storage capacity because of its irregularities . *Wind energy systems are noisy in operating . *Wind power systems have a relatively high overall weight .

APPLICATION OF WIND ENERGY * Wind energy is used in various industrial process like , food processing , textile processing , production of inorganic chemicals like chlorine , bromine etc . *Wind powered pump can be used to desalinate water . * Wind powered pump can be used for irrigation purpose .

CONCLUSION * Wind is one of the most flexible and easily handled comparing to all energy sources , since the mechanical energy derived directly from the wind can be readily and efficiently converted to other forms of energy . *The cost of power generation from wind farms has now become lower than diesel power * Wind farms are situated generally in coastal areas . * Induction generators are widely used in wind mill.

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REFERENCES 1)Renewable Energy Sources and Emerging Technologies By D.P. Kothari , K.C. Singal , R.Ranjan. 2) Non-conventional Energy Resources By B.H. Khan. 3) Wind Electrical Systems By S.N. Bhadra , D.Kastha,S.Banerjee. 4) Renewable Energy Sources and Their Environmental Impact By S.A.Abbasi,N.Abbasi