EXPERIMENT1WIND TURBINE

1.1 OBJECTIVESAfter the experiment, the students are expected: To understand the relationship between the generator's output voltage and rotation speed To determine the relationship between frequency and speed To understand how a rectifier influences the generator voltage's signal characteristic To examine operation in the storage mode at various loads and wind speeds.

1.2 BASIC THEORYA wind turbine is a device that converts kinetic energy from the wind, also called wind energy, into mechanical energy, a process known as wind power. If the mechanical energy is used to produce electricity, the device may be called a wind turbine or wind power plant. If the mechanical energy is used to drive machinery, such as for grinding grain or pumping water, the device is called a windmill or wind pump. Similarly, it may be referred to as a wind charger when used for charging batteries.The result of over a millennium of windmill development and modern engineering, today's wind turbines are manufactured in a wide range of vertical and horizontal axis types. The smallest turbines are used for applications such as battery charging or auxiliary power on boats; while large grid-connected arrays of turbines are becoming an increasingly important source of wind power-produced commercial electricity.

Theoretical power captured by a wind turbineTotal wind power could be captured only if the wind velocity is reduced to zero. In a realistic wind turbine this is impossible, as the captured air must also leave the turbine. A relation between the input and output wind velocity must be considered. Using the concept of stream tube, the maximal achievable extraction of wind power by a wind turbine is 59% of the total theoretical wind power.

Practical wind turbine powerFurther inefficiencies, such as rotor blade friction and drag, gearbox losses, generator and converter losses, reduce the power delivered by a wind turbine. The basic relation that the turbine power is (approximately) proportional to the third power of velocity remains.

TypesWind turbines can rotate about either a horizontal or a vertical axis, the former being both older and more common.Horizontal axisComponents of a horizontal axis wind turbine (gearbox, rotor shaft and brake assembly) being lifted into position A turbine blade convoy passing through Eden field, UKHorizontal-axis wind turbines (HAWT) have the main rotor shaft and electrical generator at the top of a tower, and must be pointed into the wind. Small turbines are pointed by a simple wind vane, while large turbines generally use a wind sensor coupled with a servo motor. Most have a gearbox, which turns the slow rotation of the blades into a quicker rotation that is more suitable to drive an electrical generator.Since a tower produces turbulence behind it, the turbine is usually positioned upwind of its supporting tower. Turbine blades are made stiff to prevent the blades from being pushed into the tower by high winds. Additionally, the blades are placed a considerable distance in front of the tower and are sometimes tilted forward into the wind a small amount.Downwind machines have been built, despite the problem of turbulence (mast wake), because they don't need an additional mechanism for keeping them in line with the wind, and because in high winds the blades can be allowed to bend which reduces their swept area and thus their wind resistance. Since cyclical (that is repetitive) turbulence may lead to fatigue failures, most HAWTs are of upwind design.Turbines used in wind farms for commercial production of electric power are usually three-bladed and pointed into the wind by computer-controlled motors. These have high tip speeds of over 320 km/h (200 mph), high efficiency, and low torque ripple, which contribute to good reliability. The blades are usually colored white for daytime visibility by aircraft and range in length from 20 to 40 meters (66 to 130 ft) or more. The tubular steel towers range from 60 to 90 meters (200 to 300 ft) tall. The blades rotate at 10 to 22 revolutions per minute. At 22 rotations per minute the tip speed exceeds 90 meter per second (300 ft/s). A gear box is commonly used for stepping up the speed of the generator, although designs may also use direct drive of an annular generator. Some models operate at constant speed, but more energy can be collected by variable-speed turbines which use a solid-state power converter to interface to the transmission system. All turbines are equipped with protective features to avoid damage at high wind speeds, by feathering the blades into the wind which ceases their rotation, supplemented by brakes.Vertical axis designVertical-axis wind turbines (or VAWTs) have the main rotor shaft arranged vertically. Key advantages of this arrangement are that the turbine does not need to be pointed into the wind to be effective. This is an advantage on sites where the wind direction is highly variable, for example when integrated into buildings. The key disadvantages include the low rotational speed with the consequential higher torque and hence higher cost of the drive train, the inherently lower power coefficient, the 360 degree rotation of the aerofoil within the wind flow during each cycle and hence the highly dynamic loading on the blade, the pulsating torque generated by some rotor designs on the drive train, and the difficulty of modeling the wind flow accurately and hence the challenges of analyzing and designing the rotor prior to fabricating a prototype.With a vertical axis, the generator and gearbox can be placed near the ground, using a direct drive from the rotor assembly to the ground-based gearbox, hence improving accessibility for maintenance.When a turbine is mounted on a rooftop, the building generally redirects wind over the roof and this cans double the wind speed at the turbine. If the height of the rooftop mounted turbine tower is approximately 50% of the building height, this is near the optimum for maximum wind energy and minimum wind turbulence. It should be borne in mind that wind speeds within the built environment are generally much lower than at exposed rural sites, noise may be a concern and an existing structure may not adequately resist the additional stress.Another type of vertical axis is the Parallel turbine similar to the cross flow fan or centrifugal fan it uses the ground effect. Vertical axis turbines of this type have been tried for many years: a large unit producing up to 10 kW was built by Israeli wind pioneer Bruce Brill in 1980s the device is mentioned in Dr. Moshe Dan Hirsch's 1990 report, which decided the Israeli energy department investments and support in the next 20 years.[citation needed] The Magenn Wind Kite blimp uses this configuration as well, chosen because of the ease of running.

Component of small wind turbineSmall wind turbine systems can be broken down into the following functional units: Rotor with rotor blade Wind vane Generator (permanently-excited synchronous generator) Rectifier Slip-rings for the transfer of energy Charge regulator or controller Rechargeable storage battery Inverter for operating appliances using mains voltageThe following block circuit diagram features an overview of the operational components of a small wind turbine.

Figure 1 Block circuit diagram features an overview of a small wind turbine.

1.3 EQUIPMENT1. Servo machine test (system) stand (300W) 1 each 2. Synchronous generator (12V) for small wind turbines 1 each 3. Charge controller for small wind turbines 1 each 4. Lamp board (12V) 1 each 5. Lamp board (230V) 1 each 6. Load unit 1 each 7. Stand-alone inverter (230V, 275VA) 1 each 8. Coupling sleeve (300W) 1 each 9. Coupling guard (300W) 1 each 10. Analog/digital multimeter, power and power-factor meter 1 each 11. Set of safety measuring leads (4mm) 1 each 12. Set of safety bridging plugs (4mm) 20 items 13. Safety plug connector (19/4mm) with tap 5 items

1.4 WIRING DIAGRAM

Figure 2. Determining the no-load characteristic of the generator ; Frequency and voltage of the generator

Figure 3. Voltage and frequency after rectification

Figure 4. Operation of the inverter under various loads1.5 PROCEDURE1.5.1 Determining the no-load characteristic of the generator1) Checking all equipment before start.2) Assembling the circuit as shown in the setup and wiring diagram below.3) Turning on the power switch of the control unit and the analog-digital multimeter.4) Setting the various torque or rotation speeds by turning the rotary knob manually.5) Selecting voltage button (U) in the measurement variable selector switch of the analog-digital multimeter.6) Measuring the output voltage UUW at speeds of 100 rpm to 1000 rpm. Selecting the n-const modus on the servo machine test system.7) Turning of the power switch after finish. 1.5.2 Frequency and voltage of the generator1) Checking all equipment before start.2) Assembling the circuit as shown in the setup and wiring diagram below.3) Turning on the power switch of the control unit and the analog-digital multimeter.4) Setting the various torque or rotation speeds by turning the rotary knob manually.5) Recording the signal characteristic of the output voltage UUW at speeds of 400 rpm, 700 rpm and 1000 rpm by using the oscilloscope (multimeter CO5127-1Z).6) Turning of the power switch after finish.

1.5.3 Voltage and frequency after rectification1) Checking all equipment before start.2) Assembling the circuit as shown in the setup and wiring diagram below.3) Turning on the power switch of the control unit and the analog-digital multimeter.4) Setting the various torque or rotation speeds by turning the rotary knob manually.5) Recording the signal characteristic of the output voltage UUW at speeds of 400 rpm by using the oscilloscope (multimeter CO5127-1Z).6) Turning of the power switch after finish. 1.5.4 Operation of the inverter under various loads1) Checking all equipment before start.2) Assembling the circuit as shown in the setup and wiring diagram below.3) Turning on the power switch of the control unit and the analog-digital multimeter.4) Setting the various torque or rotation speeds by turning the rotary knob manually.5) Recording the signal characteristic of the output voltage UUW at speeds of 400 rpm, 700 rpm and 1000 rpm by using the oscilloscope (multimeter CO5127-1Z).6) Turning of the power switch after finish.

1.6 RESULTS1.6.1 Determining the no-load characteristic of the generatorTable 1.1 Experiments result of the no-load characteristic of the generatorn [rpm]1002003004005006007008009001000

UUW[V]1.83.55.37.18.810.612.714.215.817.3

1.6.2 Frequency and voltage of the generator

Figure 5.Signal characteristic of the output voltage UUW at speed 300 rpm (volt/div = 10 volt ; time/div = 20 ms)

Figure 6.Signal characteristic of the output voltage UUW at speed 700 rpm (volt/div = 10 volt ; time/div = 20 ms)

Figure 7.Signal characteristic of the output voltage UUW at speed 1000 rpm (volt/div = 10 volt ; time/div = 20 ms)

1.6.3 Frequency and voltage after rectification

Figure 8.Signal characteristic of the output voltage UUW at speed 300 rpm after rectification (volt/div = 10 volt ; time/div = 20 ms)

Figure 9.Signal characteristic of the output voltage UUW at speed 700 rpm after rectification (volt/div = 10 volt ; time/div = 20 ms)

Figure 10.Signal characteristic of the output voltage UUW at speed 1000 rpm after rectification (volt/div = 10 volt ; time/div = 5 ms)

1.6.4 Operation of the inverter under various loadsTable 1.2 Inverters output voltage, current, and power at various loadsLampVoltage[V]Current[A]Power[W]

Incandescent226.70.1125.1

Energy-saving227.40.034.2

LED226.30.033.7

Figure 1.8Signal characteristic of the inverters output voltage and current (load = incandescent lamp ; volt/div = 100 volt ; ampere/div = 300 mA ; time/div = 5 ms)

Figure 1.9Signal characteristic of the inverters output voltage and current (load = energy-saving lamp ; volt/div = 200 volt ; ampere/div = 300 mA ; time/div = 5 ms)

Figure 1.10Signal characteristic of the inverters output voltage and current (load = LED lamp ; volt/div = 200 volt ; ampere/div = 300 mA ; time/div = 5 ms)

1.7 ANALYSIS1.6.1 Determining the no-load characteristic of the generator

Chart 1.1Relationship between various speed and output voltage of the generator

1.6.2 Frequency and voltage of the generator1) The generators output at 400 rpm

2) The generators output at 700 rpm

3) The generators output at 1000 rpm

The number of pole pairs on the generator

1.6.3 Frequency and voltage after rectification1) The generators output at 400 rpm

2) The generators output at 700 rpm

3) The generators output at 1000 rpm

1.6.4 Operation of the inverter under various loads1) The inverters output of incandescent lamp

2) The inverters output of energy-saving lamp

3) The inverters output of LED lamp

1.8 CONCLUSIONS1) The generator voltage increases proportionally with the speed.2) The frequency is directly proportional to the speed.3) The generator has 3 pole pairs.4) The generator voltage is rectified and has a positive value. 5) The rectified voltage contains the original generator voltage's positive and negative components. Wind Turbine1-1