wind generators

WIND GENERATOR

Under the esteemed guidance of

Mr. G. Ravindra, M. Tech., (Ph. D.),

Asst. Professor,

Dept. of EEE, SVEC.

By

D. Subhash Reddy,

12121A0234.

DEPARTMENT OF ELECTRICAL AND ELECTRONICS ENGINEERING

SREE VIDYANIKETHAN ENGINEERING COLLEGE(An autonomous institution affiliated to JNTUA, Anantapuram)

Sree Sainath Nagar, Tirupati – 517 102

A Seminar on

Dept. of EEE

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Contents

Introduction

Wind turbines

Types of Wind Turbines

Types of Generators in Wind Turbines

Wind Energy Conversion Systems

Advantages of Adjustable Speed Generators

Disadvantages

Conclusion

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Introduction 3

Wind turbines convert the kinetic energy present in the wind into mechanical energy by means of producing torque.

Among all the parts of a turbine the generator plays a vital role.

In the present scenario, most wind turbine manufacturers now equip power generating units by induction generators.

They are operated either at fixed speed or adjustable speed.

Adjustable speed generation is preferred over fixed speed generation.

Wind Turbine

A wind turbine is a device that converts kinetic energy from the wind into electrical power.

The modeling of a turbine includes parameters such as optimum tower height, control systems, number of blades and blade shape.

A quantitative measure of the wind power available at any location is called Wind Power Density(WPD).

Wind turbines are generally classified depending on their axis of rotation as:

Horizontal axis type and

Vertical axis type.

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Types Of Wind Turbines

Horizontal Axis Wind Turbine Vertical Axis Wind Turbine

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Fig.1 Fig.2

Parts Of Wind Turbine6

Fig.3

Types of Generators in Wind Turbines

Generators driven by fixed speed turbines can directly be connected to grid called Fixed Speed Generators (FSG).

Ex: Squirrel Cage Induction Generator.

Adjustable Speed Generators (ASG) need a power electronic converter interface for interconnection with the grid.

Ex: Doubly Fed Induction Generator (DFIG).

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Fixed Speed Wind Energy Conversion System(Danish Concept)

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Fig.4

Adjustable Speed Wind Energy Conversion System

In adjustable speed systems, the turbines rotor absorbs the mechanical power fluctuations by changing its

speed.

So the output power curve is smoother which greatly enhances the quality of power.

However, since adjustable speed operation produces a variable frequency voltage, so a power electronic

converter must be connected to the constant frequency grid.

It can be achieved by using:

Direct-in-Line ASG System

Doubly Fed Induction Generator ASG System

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Direct-in-Line ASG System

In this set up the stator of the induction generator will be connected to the grid by the means of back to back connected power electronic converter bridges.

Since the power converter has to convert all the stator power, the converter size depends on the stator power rating.

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Fig.5

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Fig.6

Doubly Fed Induction Generator ASG System

Advantages of ASG over FSG

Reduced acoustic noise, because low-speed operation is possible at low power conditions.

Improves system efficiency as turbine speed can be adjusted as a function of wind speed to maximize output.

Reduced mechanical stresses.

Improved power quality.

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Disadvantages of ASG 13

Use of Power Converter makes the system expensive.

The system efficiency mostly depends on the converter efficiency.

Conclusion 14

Large scale wind power projects are an attractive alternative to conventional capacity expansion as they are getting depleted.

The use of adjustable speed generators utilizing wind power as input can become a sustainable renewable energy resource in the coming future.

REFERENCES

[1] R. Pena, J. C. Clare, G. M. Asher, “Doubly-fed Induction Generator Using Back-to-back PWM Converters and Its

Application to Variable-speed Wind-energy Generation”, IEE hoc.-Electr. Power appl., Vol.143,no.3,pp.231-241,

1996.

[2] F. Blaabjerg, Z. Chen, and S. B. Kjaer, “Power electronics as efficient interface in dispersed power generation

systems”, IEEE Trans. Power Electron., Vol. 19, No. 5, pp. 1184–1194, Sep. 2004.

[3] T. Sun, Z. Chen, Frede Blaabjerg, “Voltage Recovery of Grid-connected Wind Turbines with DFIG After a Short-circuit

Fault”, 35th Annual IEEE Power Electronics Specialists Conference, 2004.

[4] http://www.intechopen.com/books

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