Presentation on

WIND ENERGY TECHNOLOGY

Ajay Bhatnagar, POWERGRID (POSOCO), New DelhiMobile: 9910952459

Wind Turbine Assembly

Overview1. Introduction and Status of Wind Energy Technology.

2. Wind Resource Assessment & Techniques.

3. Wind Turbine Components & Aerodynamics.

4. Wind Electric Generators & Types.

5. Control and Safety System of Wind Turbine System.

6. Grid Integration of wind turbines.

7. Forecasting of Wind power.

8. Offshore Wind Energy.

9. Role of NIWE in Wind Energy Development.

10. Indian Govt. policies and Overview of WTRS / WTTS.

TERMINOLOGY USED IN WIND POWER GENERATION 1/2

ANEMOMETER, SODAR & LIDAR

ANEMOMETER (A device to measure Wind speed, Force & Direction), SODAR (SOnic Detection And Ranging, used to measure the scattering of sound waves by Atmospheric Turbulance) & LIDAR (LIght Detection And Ranging, used to measure the distance of wind by illuminating the target). These instruments are used to Analyse, Measure and Study the Qulaities, Properties & Historical Data Analysis of Wind including Speed, Direction, Pressure, Temperature & Humidity etc. Anemometer: Cup, Vane, Ultra sonic & Hot wire.

CAPACITOR It is used to improve Voltage/Current but, impairs the harmonics.

DEIFIt is an organization in Denmark which was esatablished in 1933. It is a global supplier of green, safe & reliable control solutions for decentralized Power production, Marine, Off shore & Wind turbines.

ENDURANCE LIMIT It is the stress level at which a material can withstand infinite number of cycles.

FATIGUE STRENGTH It is the stress level that a material can sustain for ‘N’ no. of cycles.FILTER It is used for setting of Harmonics.GEOSTROPHIC WIND It is the steady wind, having NO Turbulance at certain height.GUST OF WIND It is sudden brief increase in speed of Wind & sustains usually for

lesser than 20 seconds.HUB GEAR It is a Gear Ratio chnging system, having arrangement of Planetary &

Epicyclic Gears used for Pitching.IREDA Indian Renewable Energy Development Agency. A non banking

financial institution for providing Term Loan to Renewable Energy.

TERMINOLOGY USED IN WIND POWER GENERATION 2/2LVRT It is Low Voltage Ride Through. It is capability of Generator to

operate during low voltage conditions.NACELLE It is a complete body structure (except Blades) at top of wind

tower, containing Rotor, Gear Box & Generator etc.PERTURBATIONS It is a small change, occurred due to Gravtational pull of a

celestial body.PITCH It is the abiltiy for change of angle of inclination of Blade for

optimising RPMs.REYNOLDS NUMBER It is the ratio of Inertial force and Viscous force.SLIP FACTOR It is the ratio of difference of speed of Motor & that of Rotor

to the speed of Motor.

STOKE'S LAWThe force that retards the sphere, moving in a viscous fluid is directly proportional to the Velocity & Radius of Sphere & Viscocity of fluid.

TORQUE It is defined as the twisting force that tends to cause the rotation.

WIND It is nothing but moving air.YAWING SYSTEM It is an arrangement of motor to rotate Nacelle according to

the direction of wind.

Introduction and Status of Wind Energy Technology

Background.

Machine design & related concepts.

Grid management issues.

New ideas

Background

• Installed capacity is more than 23 GW (& growing) which is around 9% of total installed capacity of India.

• India is 5th largest Wind power producing country in world.

• India is the only country to have separate Ministry of Non-conventional & Renewable Energy (MNRE).

• The Wind energy technology is among most technologically advanced systems. • The cost of production of Wind power is around `7 crore per MW. • Wind Power is directly proportional to V3 where, V=Velocity of wind.

• Non sharing of knowledge & versatile weather conditions are big challenges in India as compared to same in Europe.

To begin with, India had more than 20 companies largely engaged inwind turbine trade. The wind turbines were designed, manufacturedabroad and for foundation and other superstructure such as tower, every thing else came from overseas.

-Tamil Nadu is the maximum Wind power generating state of India (more than 7000 MW).

-The wind normally flows from Western side and maximum generation occurs during May to September.

-Little change in wind speed (say for 0.5 mtr/sec) can cause variation in load from 300 – 400 kW.

-Total contribution of Wind generation in Tamil Nadu is more than 50% of total generation, available from all sources.

The following are some of the challenges, faced for installing a Wind Power plant:

-Technology, to be adopted.

-Selection of Land / Site.

-Consideration of Grid connectivity Policy .

-Installation’s Utility.

-Project development enhancements.

-Skills, required in different fields.

-O&M works & their expenditures.

-Network penetration.

State wise Installed capacity of Wind Power in India

S.no: State Installed capacity as on 31.03.2015 (in MW)

1 Andhra Pradesh 1031.40

2 Gujrat 3645.40

3 Karnataka 2638.40

4 Kerala 35.10

5 Madhya Pradesh 879.70

6 Maharashtra 4450.80

7 Rajasthan 3307.20

8 Tamil Nadu 7455.20

9 Others 4.30

Total 23447.50

Asian Installed capacity of Wind Power

S.no: Name of Country Installed capacity (ending 2013) in MW

1 PR China 91412

2 India 20150

3 Japan 2661

4 Taiwan 614

5 South Korea 561

6 Thailand 223

7 Pakistan 106

8 Sri Lanka 63

9 Mangolia 50

10 Others 87

Total 115927

Machine Design• American exercises were sporadic & were concentrating on high end aerodynamic efficiencies. There was not much commercial success. Presently, there are new models coming from US.

• The European experiences in wind turbine design had been based on a rather conservative approach. Reliability was one of the design drivers.

• The design philosophy for wind turbines to attain the:

Improved Aerodynamic Efficiency– By optimized airfoil geometry.– Optimized aero elastic behavior.‐

Improved structural dynamics– Failure of components due to fatigue and extreme wind conditions.

Better tailored grid connection– Improved power factor.– Improved power quality.– Latest turbines have incorporated fault ride through designs (LVRT).

• In a Wind farm, the gap between 2 adjacent towers is maintained 5D in two columns & 7D in two rows. D=Dia. of Rotor (including blade).

• Type of Wind Towers: Lattice type. Tubular type. Guyed type.• Outages/Shutdowns etc may be Short time (6-72 hrs), Medium (3-10 days) & Long term (above 10 days).

• Wind speed of 11 metre/sec is sufficient to produce 1 or, 2 MW Wind power.

• The life of Wind Turbine is normally 20 -25 yrs.

• Slip α Torque α Power

Machine design concepts• Technologies available for wind power exploitation can be classified based on the way power control is effected:

–Stall regulated, fixed speed turbines.–Pitch controlled, fixed speed wind turbines.–Active stall regulated.–Pitch regulated variable speed. • Another possible classification is based on the generator type.

Classification by Wind Generator• Asynchronous an induction machine driven ‐ above the synchronous speed.• Doubly Fed Induction Generator (DFIG) - It is synchronous where, the following conditions are found:-if the rpm of rotor is lesser than 1000, then, it will get the Power from Grid &-- if the rpm of rotor is more than 1000 then, it will give the Power to Grid.

• Direct drive Synchronous generators.

Types of Wind Turbine Generator (WTG)

1. Horizontal Axis Wind Turbine (HAWT).2. Vertical Axis Wind Turbine (VAWT).HAWT has several technological & economical advantages.Wind Turbines are designed to operate in different Wind conditions according to the speed of Air in that area. The turbulence also play an important role in extreme wind conditions & it affects Fatigue life.

Tip Speed Ratio (TSR) TSR = ᾨR/V where, ᾨ = Rotational speed in Radians/second,R = Rotor Radius & V = Wind ‘Free stream” Velocity.It is the ratio of the speed of the rotating blade tip to the speed of free stream wind. There is an optimum angle of attack which creates the highest lift to drag ratio. The angle of attack depends on wind speed.

The Wind turbines ought to be –Efficient.–Safe to install & operate.–Have long service life.–Cost effective.

Some electrical engineering of wind turbines

• Power flow from the turbine to grid starts from either a gear box that takes care of speed matching between rotor and generator or direct drive generators.

• The generator gets connected to grid through a soft starter.

• A carefully designed feed back control system & independent safety systems will be in control.

• A normal induction generator will have a capacitor bank that gets switched in in stages.‐

• In a Motor (below synchronous), the Rotor speed >Stator speed & vice-versa in the Motor (above Synchronous).

Soft startThe generator is linked to Grid through through thyristor bank that gradually switches in the grid. Large motors will have similar soft starting devices. Once the generator is on grid, thyristors are bypassed.

Capacitors to control RKVHSwitchable capacitors provide compensation to the reactive power requirements ofinduction generators in a phased manner to see that the reactive power requirement from the grid is minimized.

Frequency convertorsA voltage based frequency convertor takes in variable input frequency f1 and gives out desired frequency f2.

Advantages of Insulated Gate Bipolar Transistor (IGBT) based power devices: They provide controllable frequency allowing a difference in the generator frequency and the grid frequency. Some of the great advantages of this device are:– Rotor behaves as an energy storage– Lower loads on downstream elements– Power capture at low wind speeds improved– Doubles as a soft starter– Lower noise levels.– Gearless designs need it.– Lends itself to implementation of LVRT more easily.

Grid Management issuesGrid connection• When wind turbines were few in number, there were no big issues.• As the installations continued at a rapid pace, there have been somewhat alarmist reactions which were mostly triggered by commercial reasons rather than technical reasons.• One should look at penetration levels before such signals are given.

Some time scales in grid management• There are four levels in grid management.– Unit commitment – which works on a scale of days.– Scheduling needed on a day upon day basis.– Load following which has a time scale of minutes to hours.– Regulation which happen over seconds to minutes.

• We need to understand that it is a complex issue and needs detailed analysis. either to accept or reject an idea.

• Often variability is mistaken to be intermittency.

New ideas

• The idea of going off shore (land to sea) -though not very ‐promising in India, but, it has fueled development of multi MW Turbines.

• There are few ideas that are virtually floating around.

–MAGLEV wind turbines which talk of thousands of MW unit sizes.

–Solar Chimney based wind turbines.

–Balloon floated wind turbines in upper atmosphere.

Wind Resource Assessment&

Techniques

Wind Regime in India

Objective of Wind Resource Assessment

Techniques of Wind Resource Assessment

Data Quality & Reliability

Modeling Techniques

What is Micro setting?

Overview of Wind Turbine Components &

Aerodynamics

Wind Electric Generators & Types

Introduction

Principle of operation of Generators

Types of Wind Electric Generator

Introduction

• Wind turbine generators differ from conventional generating units found in an electrical grid.

• The main reason is that the generator works with a continuously varying power source (the wind turbine rotor) supplying highly fluctuating mechanical power (torque).

Principle of operation of Generators

• In Wind Turbine, the basic idea is to convert the Kinetic energy to Mechanical energy for (from Wind to rotation of Blade) and from Mechanical energy to Electric energy (from Rotor - Torque convertor to Generator).

Type of Wind Generators

Principle of Induction Generator

Foundation of Tower

COST OF VARIOUS COMPONANTS (in %age) IN WIND TURBINES

Control and Safety System of Wind Turbine System

Important functions of Control system

Grid Integration of wind turbines

Technical Regulations for Wind Power

Considering the increasing penetration of Wind Power in Grid & rapid development of Wind Turbine technology, the following controls are necessary:

Active Power Control.

Reactive Power Control.

Low Voltage Ride Through.

System Perturbations.

Fault / low Voltage Ride ThroughThe ability of the Wind Turbine to remain connected to the Grid without tripping from the Grid for a specified period of time during a voltage drop at the point of connection.

During system disturbances, if generators of large generating capacity, connected to the Grid, continue their operation, this aids the system in returning to normal operation.

During a fault that causes a voltage drop at the wind turbine terminals, the reactive power demand of induction generators increases. Unless a reactive power support is available at the generator terminals, the reactive power will be drawn from the grid and further instability.

Certification requirements

Forecasting of Wind power

FORECASTINGThe purpose of Wind Generation forecasting is to minimise the deviation of forecasted vs actual generation.• Numerical Weather Prediction gives global weather forecasts with 6 hour intervals• This would be interpolated to the wind farm site and wind speeds are determined. The interpolation is– Spatial (Geographical area) &– Temporal (Time period)

• Based on past data the conversion between wind farm wind speed and power is determined.• It would be corrected using data from immediate past (SCADA).large scale integration needs• At this stage, we need to include RE power in overall grid planning with an assigned capacity.• There is a need to assign capacity to Wind power at the planning stage. • We need to improve forecasting accuracy.– The problem at input data level (weather data collection itself) needs to be addressed.– New limited area high resolution NWP models need to be developed and used.• We need to move away from approach of control by commerce. Think of rewarding a good forecast instead of penal regime. Get SLDCs to have uniform ways of dealing with schedules.• Settlement accounts should be generated automatically.

Wind power forecasting is an estimate of the expected production of one or more wind turbines in the near future

Need for forecasting

• Performance requirements for a forecasting - need of both the grid operator and the windenergy generators.• Wind energy generators - the priority is to minimize the deviation between forecasted andactual plant output.• First priority: To anticipate changes in wind production as accurately as possible in very short time (up to few hours ahead).• To enable the Load Dispatch Centers (LDCs) to manage the grid operations in an optimalfashion.• Second priority :To forecast the wind generation for the next day - to enable the LDCs toschedule the reserve capacity as efficiently as possible.• Practiced in Denmark, Germany, Spain, U.K. and U.S.A.What is a Model

Offshore Wind Energy

Overview of Offshore Wind Energy

Why Offshore Wind energy ?

World’s largest Wind farm

Offshore Wind energy – United Kingdom

Offshore Wind Energy – Indian ScenarioIndia is blessed with a huge coastline of about 7600 kms & it has significant Wind energy potential.

Environment Impact on Birds

No significant effect on fishes.- Some fish avoided/were attracted to underwater cable.- Seals did not change behavior due to wind farms.

Environment Impact on Birds

Role of NIWE in Wind Energy Development

National Institute of Wind Energry, Chennai (since 1998)

Expertise offered to Wind & Solar Energy Stakeholders

Role of NIWE:

• Research & Development.

• Wind Resource Assessment.

• Testing and Certification Services.

• Training programmes.

• Solar Radiation Resource Assessment.

Indian government policies and Overview of WTRS / WTTS

Thanks!