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