Wind turbines are normally used for following purpose
- Generation of electricity with the help of velocity of wind
- Wind turbines have ability to store electricity those are excess for future demands.
- Wind turbine also provides electricity to grid
Electricity generation basics via wind turbines
In following figure we will come to know that how electricity is generated via velocity of wind or how kinetic energy of wind is converted in to electrical energy.
Steps for installation of a wind turbine
There are following steps that we have to consider during the designing of given wind turbine.
Phase I- Site and feasibility assessment
Observation & study of wind resources
First of all we have to observe about the wind resources, it could be done with the help of anemometer that monitors the wind. We may also refer the wind speed indicator or some technical tools that provides the knowledge about wind flowing for a given time.
Location of turbine
During the designing of wind turbine we have to select the location of turbine as it will play a vital role in its performance, we should always care to locate the turbine after considering following points.
- Environmental point of view for example birds may affect the performance of our unit.
- Obstacles (like trees)availability are more or less.
- Public density
Estimation of cost
In this step we have to consider all those points where we have to pay and these are as following.
- Costing of selection and studying of sites.
- Third party consultation charges.
- Components costs such as inverter ,turbine, tower , foundation of tower , transmission system grid & wind turbine controller.
- Permission securing charges.
- Agreement charges.
- Erection & commissioning expenditures.
- Maintenance (higher) & operational costs (minor)
Phase II- Designing & financial calculations
In this step we have to carry out the following tasks
- Preparing the layout, foundation and other civil work design.
- Selection of turbine , inverter ,tower & controller on the basis of capacity of unit and site condition.
- Costing by demanding and comparing quotations of erection, commissioning & maintenance of unit and on the basis of lower cost quotation and best quality work we have to place the order.
Phase III- planning & Permission
In this step we have to secure the permission to go ahead after convenience our requirements, investment & benefits.
Phase IV- Installation or Erection of unit
In this step we have to start our civil foundation & erection work, normally we consult and appoint an installer to supervise & support the team members during erection work. We also always prefer to minimize the cost & time of erection after consulting with appointed installer.
We have to secure the permission from electric cooperation to connect our system with the grid.
Phase V- Operation & routine inspection phase
Once installation and grid connection completed, we may run our unit and it must be noted clearly that our wind turbine should be inspected on routine basis and undergoes with preventive & predictive maintenance.
Estimation of wind speed
In order to predict the power production of our turbine, first we have to understand the average speed of wind at the position of wind turbine, in order to know how average speed of wind will affect the performance and production capacity of turbine, we may refer following graph between changes in the yield of wind turbine, frequency with respect to speed of wind.
The main factor that affects the power performance will be the rotor size. Another point that affects will be the control principles for example stall control, pitch control & active stall control etc.
Power production by wind turbine may be calculated by following formula.
P= (1/2) ρ V3 A CP
P= Output power
ρ= Air density
V= wind speed
A= rotor area
CP =Efficiency factor
CP Efficiency factor is basically product of the mechanical efficiency, electrical efficiency & aerodynamics and it must be noted that these mentioned factors are dependent on speed of wind and generated power simultaneously.
Mechanical efficiency is estimated by losses in gearboxes and it must be in range of 0.95 to 0.97 as this range is acceptable at full load.
Electrical efficiency is estimated by losses in electrical circuit & generator and it must be in range of 0.97 to 0.98 as this range is acceptable at full load.
Aerodynamics efficiency -Maximum possible value = 0.59 (according to Betz law)
It is observed that the maximum value of efficiency factor will be at wind speed of 7-9 m/s and it will be maximum 50%.
In following power curve we may easily see that power generation will vary along with the speed of wind power.
Specification of 100 KW wind turbine
We may refer the following table to aware about the required specification for 100 KW wind turbine
Induction,3 Phase,480 VAC(60 Hz) or 380 VAC(50Hz)
Rated generated output power 100 KW
Double stage-Helical gear box
Gear box ratio 25:1 for 60 Hz and 20.8 : 1 for 50Hz
Input RPM = 70 and
output RPM 1800 (60 Hz) & for 50 Hz RPM will be 1500
Variable pitch designing of blade
Rotor diameter = 18 m
Swept area = 229 m2
Rotational speed 72 rpm
Fiberglass 8.3 m
Web based automated -controlling system
Energy production on annual basis
In following curve we may secure the basic information about the energy production in KWh on annual basis for given annual average wind speed.
Wind turbine foundation
Wind power unit are based on its foundation, so we need to know that how foundation of wind turbine units are made.
In following figure we have represented the elevation for tower foundation and its plan.
Points that we have to follow are specified below.
Drilling of center of piles approximate 6 m below the end of pile in order to install RCC
Installation of Reber cage in drilled out pile about 510 mm inside pile for preparing the concrete
There should be total 6 no. of piles for installation of one tower
Now pile will be undergoes through inspection of load carrying capacity, with the help of hydraulic jack as shown in below figure about a load 580 KN with allowable movement of 0.48 mm.
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