| System Description
Wind Turbine System
The major components of the FD500W wind turbine are shown as below.
 Components of a wind energy system.
Blades/Rotor System
The rotor system consists of three aluminium blades. Acting like aircraft wings, the blades convert the energy of the wind into rotational forces that can drive a generator. The aluminium blades are exceptionally strong . The rotor has three blades because three blades will run much smoother than rotors with two blades.
Alternator
The FD500W wind generator is a horizontal axis wind generator. The alternator utilizes permanent magnets and has an inverted configuration in that the outside housing(magnet can) rotates, while the internal windings and central shaft are stationary.
The output from the alternator is three-phase alternating current(ac), but it is rectified to direct current by the charge controller which is a part of the system. Since it uses permanent magnets, the alternator is generating voltage whenever the rotor is turning.
Nacelle
The nacelle is the aluminium housing around the main body of the machine. It contains the main structural backbone of the turbine(called the mainframe), assembly the yaw bearings, and the tower mount. The yaw bearings allow the wind turbine to freely pivot around the tope of the tower so that the rotor will face into the wind.
Charge Controller
The charge controller serves as the central connection point for the electrical components in the system and it provides 2 valuable control functions. It rectifies the AC output from the turbine into direct current(DC) and charge the battery. And it continually monitors the battery voltage and compares it to the regulation set point. The regulation set point is factory set to 28.2V(24V Turbine). Or 41.2V(36V Turbine). When the battery voltage rises above the set point, it automatically stops charging the battery. It will wait for the battery voltage to drop. Normal charging will resume when the battery voltage drops slightly below the fully charge level. For 24 V turbine the controller will resume charging at 22V(34V for 36V turbine).
Tower Kit(optional)
The FD500W is offered with the guyed tubular tilt tower. For installation procedures on this tower please refer to the manual of 6m LAND TOWER KIT
System Operation
Normal Operation
The rotor of the FD500W should begin to rotate when the wind speed reaches approximately 3m/s. (for the first several weeks of operation, however, the start-up wind speed will be higher because the bearing seals have not worn in) battery charging should commence shortly after the rotor spins up to speed. Once turning, the rotor will continue to turn in lower wind speeds, down to approximately 2.5m/s. the rotor speed will increase with increasing wind speed and the system will provide a higher output. This output increase rapidly because the energy available in the wind varies as the third power(cube) of the wind speed. For example, if the wind speed doubles from 5m/s to 10m/s, the energy in the wind increases by a factor of eight(2 3=2x2x2=8). One result of this relationship is that there is very little energy available in light winds. For the average site, winds in the range of 5.5 -12m/s will provide most of the system annual energy production.
High Winds – AutoFurl
During periods of high wind speeds the AutoFurl system will automatically protect the wind turbine. When furled, the power output of the turbine will be significantly reduced. In winds between 13m/s and 18m/s it is normal for the turbine to repeatedly furl, unfurl and then furl again. In winds above 18m/s the turbine should remain continuously furled.
AutoFurl is a simple and elegant method of providing high wind speed protection. The AutoFurl system is based on aerodynamic forces on the rotor, gravity, and the carefully engineered geometry of the wind turbine. As shown in Figure, the aerodynamic forces acting on the blades cause a thrust force pushing back on the
rotor. This force increases with increasing wind speeds. The thrust force acts through the centreline of the rotor, which is offset from the centreline of the tower pivot axis(yaw axis). Therefore, the thrust force on the rotor is always trying to push the rotor over to the side, away from the wind.
But the rotor is kept facing into the wind at speeds up to 12.5m /s by the wind turbine tail assembly. The tail, in turn, is kept straight by its own weight because its pivot at the back of the nacelle is inclined. So the weight of the tail holds it against a rubber bumper and the tail holds the rotor into the wind.
The geometries in the systems are carefully balanced so that at 12.5m /s the rotor force acting on the yaw-offset is large enough to overcome the preset force holding the tail straight. At this point the rotor will start turning away from the wind or furling. The tail stays aligned with the wind direction. The speed of furling depends on the severity of the wind gusts and whether the wind turbine stays furled depends on the wind speed.
As the wind turbine furls the geometry of the tail pivot caused the tail to lift slightly. When the high winds subside the weight of the tail assembly returns the whole turbine to the straight position. The AutoFurl system works whether the turbine is loaded or unloaded.
The AutoFurl system is completely passive, so it is very reliable and since there are no wear points, like in a mechanical brake system, it is very robust.
There is one situation in the field, however, that we have found can disrupt the operation of AutoFurl. If the wind turbine is installed on a sharp hill or next to a cliff so that the wind can come up through the rotor on an incline(e.g., from below; as opposed to horizontally) we know that this will affect furling and can produce higher peak outputs. We strongly recommend avoiding this situation.
The wind generator is designed to survive in wind speeds of up to 30 m /s .
Charge Controller Installation
The general electrical configuration is shown in Figure as below. In most cases the loads will be AC(alternating current) and they will be supplied through a DC-to-AC inverter.
The charge controller must be installed indoors and should be located relatively close the battery bank. Do not install the charge controller outdoors; it is not waterproof.
Step 1.
Connect battery leads. First connect the battery negative(-) wire to the terminal marked (-). Touch the positive terminal (red colo u r) with battery positive wire and withdraw quickly. If a big spark takes place, the connections are reversed. Double check everything to find the cause. Connect the battery positive wire to the terminal of red colo u r after checking.
Step 2.
Connect the three wind turbine leads to the three terminals on the controller panel. The three wires are interchangeable and are not labelled. Any leads can go to any terminal. The turbine leads should still be shorted from the turbine installation. In order to make the connections to the controller a small wire can connected to allow the turbine wires to remain shorted until the wires are fully connected to the controller.
Once all turbine leads are connected, remove the shorting wire. If there is sufficient wind then the turbine will begin turning and the turbine LED will begin blinking, indicating that the turbine is charging the battery.
Step 3.
Connect inverter. If the system includes a DC to AC inverter, connect the inverter input leads to the battery terminals, not to the charge controller. The controller circuit board is not designed to handle the high currents that are possible with inverters. Ensure that you have the correct battery size for your system ( 500 W units normally utilise 24V or 36V batteries. Ensure that the batteries used are identical types and of identical age. Mixing different types/sizes/ages of battery will cause all the batteries in the bank to fail prematurely. If you need to replace batteries, you should replace all at once.
4. Batteries
You can use any type or size of battery. However, car batteries are not designed to cope with deep charge/discharge cycles, and so they will not have a long lifespan. Truck batteries are a little better, and leisure batteries are better still. Dedicated ‘deep cycle’ batteries are the best option, as they have larger plates, larger gaps between plates, and more clearance between the plates and the bottom of the battery casing, to allow greater debris build-up before problems arise. If you are unsure about the batteries, please contact your supplier, who can advise you further.
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