Wind Energy Control
Wind Energy Control
INTRODUCTION
1.1 ENERGY
Any physical activity in this world, whether by human beings or
by nature is caused due to flow of energy in one form or the other,
energy is required to do any kind of work. The capability to do a
work depends on the amount of energy one can control and utilize.
Energy is most basic infrastructure input required for economic
growth and development of the country.
Consumption of more energy in a country indicates better quality
of life therefore the per capita energy consumption of a country is
an index of standard of living or prosperity of the people of that
country. In such a way, the total annual energy consumption of
India is 10.5*1018 joules and the per capita annual energy
consumption is 9.0*109 joules.
1.2 NON -CONVETIONAL ENERGY SOURCES IMPORTANCE
In 1973, OPEC (Organization of Petrol Exporting Countries,
founded in 1960) put an embargo on oil production and started and
oil pricing control strategy. Oil prices short up four folds
causing severe energy crisis the world over. This result in
spiraling prices rise of various commercial energy sources leading
to global inflation. The world put this shock very enormously
sensitive and for the first time, a need for developing alternative
sources of energy was felt. The result of such a situation brought
the use of non-conventional energy resources.
1.3. SALIENT FEATURES OF NON-CONVENTIONAL ENERGY
RESOURCESMerits1. Non-conventional sources are available in nature,
free of cost.2. The cause no or very little pollution. Thus by and
large, they are environment friendly.3. They are in exhaustible.4.
They have low gestation period.Demerits 1. Though available freely
in nature, the cost of harnessing energy from non- conventional
energy resources is high, as in general, these are available in
dilute forms of energy.2. Uncertainty of availability: the energy
flow depends upon various natural phenomena beyond human control.3.
Difficulty in transporting these forms of energy.
1.4 WIND ENERGY IMPORTANCE
Non-conventional technologies are presently under development
stage. At present, its share is very small. Some of those resources
are solar energy, wind energy, biomass energy, geo-thermal energy,
ocean tidal energy, ocean wave and ocean thermal energies.
Among all the prescribed, wind energy is promising and excellent
source because of its relative competitiveness in cost and absence
of atmospheric pollution. It has gain considerable attention and
acceptability throughout the world and also in our country, for
electric power generation.
The installation cost of wind energy is Rs.4crore/MW which is
comparatively far less than the installation cost of solar energy
i.e., Rs.20crore/MW. Although, wind energy may not be able to
replace the conventional sources of power which are likely to be
the main stay for the near future, wind can definitely compliment
the main conventional sources of energy for immediate short fall of
power. The interest in wind energy has been renewed after the oil
crisis of 1973. Most modern, large scale-wind energy systems, built
after 1980 use modern engineering designs, materials and
incorporate micro-electronics monitoring and control. With modern
blade materials, the expected life of wind turbine has exceeded
20years, improved turbine designs and plant utilization have
contribute to reduction of large scale wind energy generation cost
from Rs.17.0/Kwh in 1980 to Rs.2.50/Kwh at present in favorable
locations. The installation cost has come down to Rs.4crore per MW
with only one year energy payback period. It is the fastest growing
energy source among all renewable in recent years with record
annual growth of 30%. Due to these reasons wind energy is gaining
an increasing acceptance and is competing with all conventional and
non-conventional sources.
1.5 INTRODUCTION TO WIND ENERGYThe circulation of air in the
atmosphere is caused by the non-uniform heating of the earths
surface by the sun. When the air immediately above a warm area
expands, it is forced upwards by cool, denser air which flows in
from surrounding areas causing a wind. Wind Energy is the Kinetic
Energy associated with the movement of large masses of air. These
motions result from uneven heating of atmosphere by the sun,
creating temperature, density and pressure differences. It is
estimated that 1% of all solar radiation falling on earth is
converted into Kinetic energy of the atmosphere, 30% of which occur
in the lowest 1000m of elevation. It is thus an indirect form of
solar energy. In contrast to diurnal availability of direct solar
radiation, wind energy can be available continuously throughout a
24 hour day for much longer periods, though it can vary a renewable
source. It is clean, cheap and eco-friendly renewable resource.Wind
energy is harnessed as mechanical energy with the help of wind
turbine. The mechanical energy thus obtained can either be used as
such to operate farm appliances, water pumping etc., or converted
in to electric power and used locally or fed to a grid. A generator
coupled to wind turbine is known as Aero generator. Very slow winds
are useless, having no possibilities of power generation. On the
other hand, very strong stormy winds cant be utilized due to the
safety of turbine. Moderate to high-speed winds typically from
5mts/sec to about 25mts/sec are considered favorable for most wind
turbines. India has wind power installed capacity of 9645MW ranks
fifth in its size of wind power program. Indias wind energy program
was initiated in the year 1984. The demonstration projects began in
1985, and are still being implemented through nodal agencies and
state electricity boards in India.Usually, the highest average wind
velocities are found near the coasts and in mountainous areas in
land. In general, there are two main types of wind turbine.
Vertical Axis wind turbines (VAWTS) and Horizontal Axis wind
turbines (HAWTS).
HAWTS are much more common in domestic situations and the most
familiar type. VAWTS are more suited to commercial applications and
are excellent at operating in confused wind areas. They are less
aesthetically pleasing but very effective at lower wind speed.
TECHNICAL DETAILS2.1 Site Selection ConsiderationsThe power
available in the wind increases rapidly with speed, hence wind
energy conversion machines should be located preferable in areas
where the winds are strong and persistent. High annual average wind
speed Availability of anemometry data Availability of wind Vt curve
at the proposed site Wind structure at the proposed site Altitude
of the proposed site Terrain and its aerodynamic Local ecology
Distance to Roads or Railways Nearness of site to local
center/users Nature of ground Favorable land cost Other
conditionsBy considering above points the reasonable sites are
First best site, for wind energy are found offshore and the
seacoast an average value on the coast is 2400kwh/m2 per year The
second best sites are in mountains. A typical average value is
1600kwh/m2 per year The lowest level of the wind energy is found in
plains where values are generally three or four times lower than
that at the coast. A typical average is 750kwh/m2 f2.2 Wind power
density Wind power density is a useful way to evaluate the wind
resources available at a potential site. The wind power density,
measured in watts per square meter, indicates how much energy is
available at the site for conversation by a wind turbine. Classes
of wind power density for two standard wind measurements heights
are listed in the below table. Wind speed generally increases with
height above ground. They have been measured traditionally at a
standard height of ten meters where they are found to be 20-25%
greater than close to the surface. At a height of 60 m they may be
30-60% higher because of the reduction in the drag effect of the
earths surface.
Table: Wind power densityClasses of Wind Power Density at 10 m
and 50 m
10 m (33 ft)50 m (164 ft)
Wind Power ClassWind powerDensity(W/m2)Speedm/s (mph)Wind
powerDensity(W/m2)Speedm/s (mph
18.8(19.7)
WIND TURBINEWind turbines available in many sizes and
configurations and are built from wide range of materials. In
simple terms, a wind turbine consists of a rotor that has wing
shaped blades attached to a hub, a nacelle that houses a drive
train consisting of a gearbox, connecting shafts, support bearings,
the generator, plus other machinery, a tower and ground mounted
electrical equipment.
Fig.3. Typical upwind vertical-axis Wind Turbine The wing shaped
blades on the rotor actually harvest the energy in the wind stream.
The rotor converts the kinetic energy in the wind to rotational
energy transmitted through the drive train to the generator.
Generated electricity can be connected directly to the load or feed
to the utility grid.3.1 MAIN COMPONENTS OF WIND TURBINETOWERS`The
tower on which a wind turbine is mounted is not just a support
structure. It also raises the wind turbine so that its blades
safely clear the ground and so it can reach the stronger winds at
higher elevations. Maximum tower height is optional in most cases,
except where zoning restrictions apply. The decision of what height
tower to use will be based on the cost of taller towers versus the
value of the increase in energy production resulting from their
use. Larger wind turbines are usually mounted on towers ranging
from 40 to 70 meters tall. Fig.4.TowerTowers must be strong enough
to support the wind turbine and to sustain vibration, wind loading
and the overall weather elements for the lifetime of the wind
turbine. Tower costs will vary widely as a function of design and
height. Some wind turbines are sold complete with tower. More
frequently, however, towers are sold separately.WIND VANEA weather
vane is also called a wind vane. It is one of the weather tool for
measuring wind direction. It is used to measure the direction of
the wind. Weather vanes can only measure wind direction a few yards
(meters) off the ground. The weather vane spins on a rod and points
in the direction from which the wind comes. Large, helium-filled
weather balloons are used to measure winds high above the earth's
surface. The balloons move with the same speed and direction as the
wind.
To determine wind direction, a wind vane spins and points in the
direction from which the wind is coming and generally has two
parts, or ends: one that is usually shaped like an arrow and turns
into the wind and one end that is wider so that it catches the
breeze. Fig.5. Wind VaneThe arrow will point to the direction the
wind is blowing from so if it is pointing to the east, it means the
wind is coming from the east. Additionally, wind direction is where
the wind is blowing from. WIND ANEMOMETER Fig.6. Wind AnemometerAn
anemometer with 4 evenly spaced cups would barely turn in a wind
where as a 3 cup version would spin rapidly. With 3 cups spaced 120
apart, one cup will always be more strongly pushed in one direction
than the other two cups are pushed in the opposite direction. In a
4-cup design the forces might balance and cancel out. Additionally
a half spherical shaped cup offers more resistance to air movement
coming toward the open end than air coming from the rounder back of
the cup.
WIND ROTOR BLADESUsually flat objects connected to a centre
shaft that converts the push of the wind into a circular motion in
a wind turbine. Most wind turbines have three blades. Very small
turbines may use two blades for ease of construction and
installation. Vibration intensity decreases with larger numbers of
blades. Noise and wear are generally lower, and efficiency higher,
with three instead of two blades. Fig.7. rotor BladesTurbines with
larger numbers of smaller blades operate at a lower Reynolds number
and so are less efficient. Small turbines with 4 or more blades
suffer further losses as each blade operates partly in the wake of
the other blades. Also, the cost of the turbine usually increases
with the number of blades. One of the strongest construction
materials available (in 2006) is graphite-fibre in epoxy, but it is
very expensive and only used by some manufactures for special
load-bearing parts of the rotor blades. Modern rotor blades (up to
126 m diameter) are made of lightweight pultruded glass-reinforced
plastic, smaller ones also from aluminium, or sometimes laminated
wood.HUBThe blades on the wind turbines are bolted to the hub.
Older wind turbines (up to and including the 95 kW models) with
Aero star blades, have a flange joint, where the glass fibre is
moulded out in a ring with steel bushes for the bolts. The newer
wind turbines (from the 150 kW models) have threaded bushes glued
into the blade root itself. In both cases bolts from the blade pass
through a flange on the cast hub. The flange bolt-holes are
elongated, enabling the blade tip angle to be adjusted.
Fig.8. Wind Turbine Hub In producing SG cast iron several
special materials, mainly silicon, are added during casting. After
casting has taken place, it is further heat treated for about 24
hours, thereby changing the free carbon from their usual flakes
into small round balls. The name SG cast iron is also short for
Spherical Graphite cast iron.GEAR BOXOne of the most important
component in the wind turbine is gearbox. Placed between the main
shaft and the generator, its task is to increase the slow
rotational speed of the rotor blades to the generator rotation
speed of 1000 or 1500 revolutions per minute (rpm). Without much
previous experience with wind turbines, one might think that the
gearbox could be used to change speed, just like a normal car
gearbox.Gears connect the low speed shaft to the high speed shaft
and increase the rotational speeds from about 30 to 60 rotations
per minute (rpm) to about 1200 to 1500 rpm, the rotational speed
required by most generators to produce electricity. The gear box is
costly (and heavy) part of the wind turbine and engineers are
exploring direct-drive generators that operate at lower rotational
speeds and dont need gear boxes. 1 Hollow shaft2 Intermediate
shaft3 High speed shaft for the generator Slow set4 Large toothed
wheel5 Small toothed wheelHigh speed set6 Large toothed wheel7
Small toothed wheel
Fig.9. Gear BoxIn this case the gearbox has always a constant
and a speed increasing ratio, so that if a wind turbine has
different operational speeds, it is because it has two different
sized generators, each with its own different speed of rotation (or
one generator with two different stator windings).
BRAKEA disc brake which can be applied mechanically,
electrically, or hydraulically to stop the rotor in
emergenciesCONTROLLERThe controller starts up the machine at wind
speeds of about 8 to 16 miles per hour (mph) and shuts off machine
at about 65 mph. Turbines cannot operate at wind speeds above about
65 mph because their generators could over heat.Low-speed shaft The
rotor turns the low-speed shaft at about 30 to 60 rotations per
minute.High speed shaftDrives the generator.Nacelle The rotor
attaches to the nacelle, which sits atop the tower and includes the
gear box, low- and high-speed shafts, generators, controller, and
brake. A cover protects the components inside the nacelle. Some
nacelles are large enough for a technician to stand inside while
working.Pitch Blades are turned, or pitched, out of the wind to
keep the rotor from turning in winds that are too high or too low
produce electricity.Yaw driveUpwind turbine face into the wind; the
yaw drive is used to keep the rotor facing into the wind direction
changes. Downwind turbine dont require a yaw drive; the wind blows
the rotor down wind.Yaw motorPowers the yaw drive.
3.2 Tip Speed RatioIn reference to a wind energy conversion
devices blades, the difference between the rotational speed of the
tip the blade and the actual velocity of the wind. High efficiency
3-blade turbine have tip sped ratios of 6-7. On the whole, high tip
speed ratio is better, but not to the point where the machine
becomes noisy and highly stressed. The tip speed ratio will
determine how fast the wind turbine will want to turn and slow has
implications for the alternator that can be used.Modern wind
turbine are designed to spin at varying speeds. Use of aluminium
and composites in their blades has contributed to low rotational
inertia, which means that newer wind turbines can accelerate
quickly if the winds pick up, keeping the tip speed ratio more
nearly constant. Operating closer to their optimal tip speed ratio
during ener allows wind turbines to improve energy capture from
sudden gusts that are typical in urban settings. In contrast, older
style wind turbines were designed with heavier steel blades, which
have higher inertia, and rotated at speeds governed by the AC
frequency of the power lines. The high inertia buffered the changes
in rotation speed and thus made power output more stable.A wind
energy conversion device that produce electricity; it typically has
one, two, or three blades. Wind turbines can be classified into the
vertical axis type and the horizontal axis type. Most modern wind
turbines use a horizontal axis configuration with two or three
blades, operating either downward or upwind.Wind turbines can be
for used stand-alone applications, or they can be connected to a
utility power grid or even combined with a photovoltaic (solar
cell) system, batteries, and diesel generators, called hybrid
systems. Stand-alone turbines are typically used for water pumping
or communications. However, homeowners and farmers in windy areas
can also use turbines to generators electricity. For utility-scale
sources of wind energy, a large number of turbines to generate
electricity built close together to form a wind turbine.A wind
turbine can be designed for a constant speed of variable speed
operation. Variable speed wind turbines can produce 8% to 15% more
energy output as compared speed counterparts; however, they
necessitate power electronic converters to provide a fixed
frequency and fixed voltage power to their loads. Most turbine
manufactures have opted for reduction gears between the low speed
turbine rotor and the high speed three-phase generators. Direct
drive configuration, where a generator is coupled to rotor of a
wind turbine directly, offers high reliability, low maintenance,
and possibly low cost for certain turbines. 3.3 Generator A device
for converting chemical, mechanical, or some other type of energy,
into electricity power. Electromagnetic generators are the main
source of electricity in the world today. They may be driven by
steam turbines, wind turbines, internal combustion engines.Or a
moving part of some other type of machine. A generator is the
reverse of an electric motor, which uses electricity to produce
another form of energy. Fig.10. Generator
In the case of solar technology, a solar module, or a system of
modules, is considered to be a generator. Generators are rated by
watts (W). To determine which size generator is right for your
needs following these steps1. Find amperage and voltage and
information for each appliance of tool being used2. Multiply the
volts (V) by the amps(A) to determine the watts youll need3. Choose
a generator that meets or exceeds your total wattage requirement3.4
Wind Turbine Braking Over sped control of a wind is exerted in two
main ways; aerodynamic stalling or furling and mechanical braking.
Furling is the preferred method of slowing wind turbines. Braking
of wind turbine can also be done by dumping energy from the
generator into a resistor bank, thereby converting the kinetic
energy of the turbine rotation into heat. This method is useful if
the connected load on the generator is suddenly reduced or is too
small to keep the turbine speed within its allowed limit.
Cyclically braking causes the blades to slow down, which increases
the stalling effect, reducing the efficiency of the blades. This
way, the turbines rotation can be kept at a safe aped in faster in
winds while maintaining (nominal) power output.A mechanical drum
brake or disk brake is used to hold the turbine at rest for
maintenance. Such brake are applied only after furling and
electromagnetic braking have reduced the turbine speed, as the
mechanical brakes would wear quickly if used to stop the turbine
from full speed.Constant-Speed Wind TurbineA wind turbine that
operates at a constant rotor revolutions per minute (RPM) and is
optimized for energy capture at a given rotor diameter at a
particular speed in the wind power curve.Cut-in Speed Cut-in speed
is the minimum wind speed at which the wind turbine will generate
usable power. This wind speed is typically between 7 and 10
mph.Rated SpeedThe rated speed is the minimum wind speed at which
the wind turbine will generate its designated rated power. For
example, a "10 kilowatt" wind turbine may not generate 10 kilowatts
until wind speeds reach 25 mph. Rated speed for most machines is in
the range of 25 to 35 mph. At wind speeds between cut-in and rated,
the power output from a wind turbine increases as the wind
increases. The output of most machines levels off above the rated
speed. Most manufacturers provide graphs, called "power curves,"
showing how their wind turbine output varies with wind
speed.Cut-out SpeedAt very high wind speeds, typically between 45
and 80, mph most wind turbines cease power generation and shut
down. The wind speed at which shut down occurs is called the
cut-out speed. Having a cut-out speed is a safety feature which
protects the wind turbine from damage. Shut down may occur in one
of several ways. In some machines an automatic brake is activated
by a wind speed sensor. Some machines twist or "pitch" the blades
to spill the wind.
CONVERSION OF KINETIC ENERGY TO ELECTRICAL ENERGY 4.1. WIND
ENERGY CONVERSION SYSTEMS (WECS)
A wind energy conversion system converts wind power into some
form of electrical energy. In particular, medium and large scale
WECS are designed to operate in parallel with a public or local AC
grid. This is known as Grid Connected system. A small system,
isolated from grid, feeding only to local load is known as
Autonomous mode, decentralized and Stand alone or Isolated power
system. A general block diagram of a grid connected WECS is shown
in figure11. The turbine shaft speed is stepped up with help of
gears, with fixed gear ratio, to suit the electrical generator and
fine tuning of speed is incorporated by pitch control. This block
acts as a drive for generator.
Fig.11. General Block Diagram of WECS
DC, Synchronous or Induction generators are used for mechanical
to electrical power conversion depending up on the design of
system, The interface, that may consists of power electronic
converter, transformer and filter, conditions the generated power
to grid quality power. The control unit monitors and controls the
interaction among various blocks. It derives the reference voltage
and frequency signals from the grid and receives wind speed,
direction, wind turbine speed signals etc. process them and
accordingly controls various blocks for optimal energy
balance.Before converting supply is fed from grid to rotor through
control room for excitation of blades after blades attaining 7m/sec
grid is cutoff by the control room.
Based on the generator drive, two schemes have been developed
for the operation of WECS1. Fixed Speed drive scheme2. Variable
speed drive scheme.
4.1.1 Fixed Speed Drive Scheme
In this scheme, constant speed is maintained at the shaft of the
generator by pitch control. A synchronous or induction generator is
used to generate Electrical Energy. Induction generator is gaining
more acceptability due to its ability to absorb small variations in
shaft speed. Two types of fixed-speed drive schemes are
possible.
i. FIXED-SPEED DRIVE
Shaft speed is held fixed for the whole range of wind speed. The
major disadvantage of one fixed speed drive is that it never
captures the wind energy at peak value of power coefficient, Cp.
Wind energy is wasted when wind speed is higher or lower than the
optimal value, corresponding to Cpmax. Because of low annual energy
yield, the use of fixed-speed drive is limited to small
machines.
ii. DUAL FIXED-SPEED DRIVE
This scheme increases the energy capture, reduces electrical
losses & reduces gear noise. The speed setting is changed by
setting the gear ratio. The Induction generator is designed to
operate at two speeds. This is achieved by either having two stator
windings with different number of poles or using single winding
with pole changing arrangement by connecting windings coils in
series or parallel.
4.1.2 Variable Speed Drive Scheme
The mechanical power produced by a wind turbine is proportional
to the cube of the wind speed. The rotational speed of the wind
turbine for which maximum power is obtained is different for
different wind speeds. Therefore variable speed operation is
necessary to maximize the energy yield. Variable speed turbines are
connected to the grid via a PEC that decouples the rotational speed
of the wind turbine from the grid frequency, enabling variable
speed operation. Two basic concepts exist for variable speed
turbines. The first concept has a electric generator with a
converter connected between the stator windings and the grid
network shown in Fig.12.
Fig.12. Variable Speed Wind Turbines with Full-Size Converter
Fig.13. Variable Speed Wind Turbines with Double-Fed Induction
Generator
The converter has to be designed for the rated power of the
turbine. The generator is mostly a (permanent magnet) synchronous
machine. Some types do not have a gearbox: the direct-drive
concept. An alternative concept is a wind turbine with a double-fed
induction generator (DFIG), which has a converter connected to the
rotor windings of the wound-rotor induction machine, in Fig.13.
This converter can be designed for a fraction (~ 30%) of the rated
power.
4.2 GENERATOR OPERATIONAs we have previously mentioned, the
asynchronous motor can also run as agenerator. This simply happens
when you, instead of forcing the rotor to turn at a rotational
speed lower than the synchronous speed, exceed this synchronous
speed by applying an outside energy source, such as a diesel motor
or a set of wind turbine rotor blades. Once again, the greater the
difference between the rotating magnetic field of the stator (which
is always 1.500 rpm) and the speed of the rotor, the greater the
torque produced by the rotor. When a working as a generator, the
rotating field however acts as a brake in slowing the rotor. The
stator experiences a variable magnetic field from the rotor that
drags its rotating magnetic field and thereby induces an electrical
current in the stator. In comparison to motor operation the induced
currents in the rotor and stator will flow in the opposite
direction, which means that power will be sent to the grid. The
faster the rotor turns in relation to the rotating magnetic field
of the stator, the greater the induction in the stator and the
greater the production of power. In practice the difference between
the speed of rotational magnetic field of the stator and the
rotational speed of the rotor is very little. A rotor will
typically turn about 1% faster at full power production. If the
synchronous rotational speed is 1.500 rpm then the rotor rotational
speed at full power will be 1.515 rpm. The interesting torque curve
of the asynchronous electric motor, also operating as a generator,
is shown below. At speeds below the synchronous rotational speed,
the motor yields a positive torque.
Typically a maximum torque of about 2.5 times the torque of the
nominal power. If the rotational speed exceeds the synchronous
level, the torque becomes negative,generator acts as a brake. All
these action are controlled by control room where reading of
frequency,speed, faultcalculation,working hours are noted
clearly.Generated power for daily,weekly,monthly,annnually are
noted clearly. The generated power is step up to transformer and
fed to 33kv lines through grid which is utilised by houses and
industries nearby . Benefits and Disadvantage of Wind EnergyWind
energy is an ideal renewable energy because It is a pollution-free,
infinitely sustainable form of energy. It doesnt require fuel. It
doesnt create greenhouse gases. It doesnt produce toxic or
radioactive wasteWind energy is quiet and doesnt present any
significant hazard to birds or other wildlife. When large arrays of
wind turbines are installed on farmland, only about 2% of the land
area is required for the wind turbines. The rest is available for
farming, livestock, and other uses.Landowners often receive payment
for the use of their land, which enhances their income and
increases the value of the land. Ownership of wind turbine
generators by individuals and the community allows people to
participate directly in the preservation of our environment.Each
megawatt-hour of electricity that is generated by wind energy helps
to reduce the 0.8 to 0.9 tones of greenhouse gas emissions that are
produced by coal or diesel fuel generation each year. Financial
Benefits 80% Depreciation the first year. Operation and maintenance
costs are low. Zero input fuel cost. Pay back in shorter duration.
Cost of generation is almost zero after the pay back period. Zero
import duty on certain parts. Tax holiday for newer power projects
for 5 years. Wheeling to SEB is easy, so no marketing problems.
The below table shows variation in capital cost which plays a
vital role in selection of renewal source for generation of
powerTable.4. Renewable Source cost of GenerationRENEWABLE SOURCES
COST OF GENERATION
SOURCECAPITALCOST (Rs. Crores /MW)GENERATION COST (Rs. /
KWH)
WIND POWER 3.5 2.25SMALL HYDRO 3.5-6.0 1.50-3.50CO-GENERATION
2.0-2.5 2.00-2.50SOLAR 30.0 15.00-20.00PHOTOVOLATAIC 9.0 5.80SEA
WAVE 2.4 1.10BIOMASS - -GASIFIER - -
DisadvantagesWind power must compete with conventional
generation sources on a cost basis. Depending on how energetic a
wind site is, the wind farm may not be cost competitive. Even
though the cost of wind power has decreased dramatically in the
past 10 years, the technology requires a higher initial investment
than fossil fuelled generators.The major challenge to using wind as
a source of power is that wind is intermittent and it does not
always blow when electricity is needed. Wind energy cannot be
stored (unless batteries are used); and not all winds can be
harnessed to the timing of electricity demands. Good wind sites are
often located in remote locations, far from cities where the
electricity is needed. Wind resource development may complete with
other uses for the land and those alternative uses may be more
highly valued than electricity generation.Although wind power
plants have relatively little impact on the environment compared to
other conventional power plants, there is some concern over the
noise produced by the rotor blades, aesthetic (visual) impacts, and
sometimes birds have been killed by flying in to the rotors. Most
of these problems have been resolved or greatly reduced through
technological development or by properly sitting wind plants.5.2
Safety RegulationsInspections of Wind Turbine Do not stay under the
turbine if unnecessary and never directly under the blades when the
turbine is in operation. If the turbine is to be looked at when
operating, it must be done from the wind side in a reasonable
distance (about 25m). Do not let the area around the turbine or the
turbine itself becomes a playground for children. The owner of the
turbine has a responsibility her too. If necessary, the turbine can
be enclosed with a fence. The controller must be locked after use,
to prevent unauthorized personal from operating, and eventually
damaging the machine.The Controller When working in the controller
and the switch board, the main switch must be switched off. It is
extremely dangerous to open the switch board when the main switch
is not in the OFF-position. When the main switch is the
OFF-position, the door to the switch board can be opened, and the
16A thermal cut-out (fuse) can be switched off. After doing this
there is no current in switch board after the main switch. The
cabinets must only be opened by the electrician or servicemen. No
seals must be broken in insertion modules. If the seal is broken,
or if modules otherwise have been put out of operation, the
guarantee and the product responsibility is no longer valid .Safety
Equipments Firm footwear with a rubber-sole . Safety-helmet .
Safety-belt with safety lock(supplied for the wind farm).RGUKTPage
14