Wind Energy Technology: Wind Turbines working and operation.

1. Renewable Energy.

Renewable energy is a source of clean, everlasting and progressively competitive energy. They differ from fossil fuels principally in their diversity, abundance and potential for use anywhere on the planet.

2. BioEnergy.

3. Geothermal Energy:

4. Wind Energy:

5. Solar Energy.

6. Hydropower:

1. Wind Energy Advantages.

Followings are the advantages of wind energy production.

a. Combat Climate Change.

b. Energy Security.

c. Cost Effective.

d. Jobs Creation.

e. Fast Installation.

f. Inexhaustible and Renewable energy source.

g. No Water consumption.

2. Disadvantages of Wind Energy.

Followings are the disadvantages of wind energy production.

a. Reliability issue.

b. Disturbance to Wildlife.

c. Turbine Noise.

d. Remote Location.

e. Require Massive Space.

1. History.

The Wind has been used as a source of energy for more than 1500 years. In times when other sources of energy were unknown or uncommon, wind energy represented a successful means for industrial and economic development.

a. Worldwide Business of Wind Energy:

The latest report by the World Wind Energy Association 2018 revealed very surprising facts above the development of Wind power in the world.

The overall capacity of all wind turbines installed worldwide by the end of 2018 reached 591 Gigawatt, according to initial statistics published by WWEA. 50’100 Megawatt were added in the year 2018.

2. Wind Energy extraction Techniques:

Four main technologies are used to extract wind energy; these are.

i. Rotating lift based machine.

ii. Rotating Drag based Machines.

iii. Flying lift based machine.

iv. Machines using flow-induced vibration.

3. Turbine Types w.r.t Wind Direction.

Considering the direction of the wind, the wind turbines are divided into two types which are upwind turbines and downwind turbines.

i. Upwind turbines.

ii. Downwind Turbines.

1. Wind Energy Basics.

Wind turbines work by converting the kinetic energy in the wind first into rotational mechanical energy through turbine rotor and then electrical energy through generator coupled with a high-speed gearbox. The simplified mechanical conversion formal is shown below.

The theoretical maximum power coefficient could be 59%. As the 100% of the kinetic energy of wind is converted into power only if the wind on backside of the rotor blade is zero which is practically impossible.

2. Turbines Power Curve.

As already explained, power production from a wind turbine is a function of wind speed. The relationship between wind speed and power is defined by a power curve, which is unique to each turbine model and, in some cases, unique to site-specific settings.

3. Why large Wind turbines have Three Blades.

The power production from three blades is optimal and the cost is also reasonable therefore most wind turbines have three blades.

1. Energy Projections for Wind Project.

The feasibility study of a wind project is crucial for the selection of best project site. Among the many factors in feasibility, one of the critical factors is wind modelling and wind resources assessment. The wind project could be installed only if the project site has plenty of winds available throughout the year.

Energy Projection.

Special software packages are used for the calculations of energy projection of wind farm. One of the common software which is specially designed for wind energy project is wind Atlas analysis (WAsP). The WAsP software package is the industry standard for wind resource assessment, siting and energy yield calculation for wind turbines and wind farms. The WAsP software is used for sites located in all kinds of terrain all over the world.

There are several types of energy losses in a wind farm, common losses are

Wake Losses

Availability Losses

Electrical Losses

Performance Losses

Curtailment

Uncertainty

1. Wind Turbine Components

The wind turbines consist of multiple components, the multi-megawatt onshore and offshore wind turbines have similar external components. In this module, I am explaining the main external components and components inside the nacelle of a wind turbine.

followings are the main components of the wind turbine.

a. Wind Turbine Foundation.

The type and design of the offshore foundations are selected by studying the depth and undersea soil characteristics. Typically, five types of offshore foundations are installed, these are

Monopile

Jacket

Tripod

Semisub

Floating Spar Buoy

b. Tower.

The tower is the largest and heaviest part of the wind turbine. The towers could be of different heights ranging between 40 meters to 150 meters tall and weigh several hundred tonnes.

Tubular Steel Towers.

Lattice towers.

Tripod tower.

c. Nacelle.

d. Rotor.

2. Wind Turbine Drivetrain.

The drivetrain is the component of the wind turbine that transforms the rotational mechanical energy generated by the rotor into electrical energy. The drivetrain composed of several elements, each of which contributes to a specific task. There are many possible configurations for the drivetrain depending upon the designer criteria.

Four common configurations include

The modular drive

The integrated drivetrain,

The partially integrated drivetrain,

The direct drivetrain.

3. Degree of Freedom in Wind Turbines.

The large wind turbines have three degrees of freedom which are Yaw, Pitch and Azimuth.

Yaw.

Pitch.

Azimuth.

1. Wind Turbine Yaw System:

The wind is natural phenomena and it keeps changing the direction frequently. For the optimal production of energy, the wind turbines must be fully aligned with the wind direction. The yaw mechanism allows the turbine to face the wind that is to align the plane of rotation to be perpendicular to the direction of the wind. Followings are the two main types of Yaw control.

a. Passive Yaw.

b. Active Yaw.

2. Yaw Drive Mechanism:

To actively monitor Yaw, a set of equipment are installed between the nacelle and the tower of the wind turbine. This set of equipment is known as yaw drive.

3. Yaw Control:

The active yaw control system uses a closed-loop feedback control technology. In a closed-loop control system, the sensors measure the actual state of the process and pass on these measurements to the controller, the controller analysis the received signals and execute a built-in algorithm, after analyzing the system status the controller sends output signals to actuators to change the state of the process.

a. Yaw Brake. The wind turbines are continuously under several external forces. The yaw mechanism is also equipped with yaw brake to stable turbines.

1. Wind Turbine’s Power control:

The wind turbines aerodynamic pitch control is designed to control the power output and speed of wind turbines. The cutting edge pitch control enables wind turbines to control power output by increasing or decreasing the angle of attack of turbine blades.

Usually, three types of pitch controls are used in wind turbine design.

Ø Stall control.

Ø Active Stall control.

Ø Pitch control.

2. Pitch Drive Mechanism.

Two types of pitch drive mechanisms are used in modern wind turbines. Some turbines manufacture use Hydraulic pitch drive while the others use an Electrical pitch drive system.

a. Hydraulic Pitch Drive.

b. Electrical Pitch Drive.

3. Pitch Control System.

The pitch controller receives wind measurements from anemometer and torque demand from the generator, each controller has built-in control instructions, based on feedback, these control instructions generate pitch angle set-points for every single blade.

a. Pitch Brake.

The electrical pitch system has integrated electromagnetic pitch brakes to stable pitch angles at specific degree and to hold pitch blades.

The hydraulic pitch has a piston-cylinder mechanism to control blades angles and piston-cylinder movement also control pitch braking system; therefore, there is no need for pitch brakes in the hydraulic pitch system.

The layout of a Wind Farm.

A wind farm consists of several wind turbines in the same location used to produce electricity. Wind farms vary in size from a small number of turbines to several hundred-wind turbines covering a widespread area. Wind farms can be either onshore or offshore. The wind turbines are connected with the electrical substation. The electrical substation is the part of a power system in which the voltage is transformed from high to low or low to high for transmission, distribution, protection and switching. The power transformer, circuit breaker, bus-bar, disconnector/insulator, lightning arrester/surge arrester, CTs and VTs are the main components of an electrical substation.

I will explain the following topics in Windfarm layout.

I. Wind Turbines Loops.

II. MV (Medium Voltage) Switchgear.

III. MV collection System.

IV. Power transformers.

V. HV (High Voltage) Switchgear.

VI. HV busbar.

VII. Voltage Levels in Wind Farm.

Careers in Wind Energy.

Wind energy is one of the fastest-growing renewable energy. In 2019, the global Wind installations were observed at 60.4 GW.

According to 2019 international renewable energy agency report, the wind industry can employ 3.74 million people by 2030 and more than 6 million people by 2050. To maximize outcomes of the energy transition, however, a holistic policy framework is needed.

I will discuss the main career opportunities in wind energy lifecycle.

a. Project Developers.

b. GIS specialists.

c. Wind Energy Analyst.

d. Wind Energy Engineers.

e. Wind Turbine Technicians.