Two Blade Teetering Rotor. Many existing small turbines use 3 rigidly mounted blades. When a three bladed turbine yaws, the rotor places large gyroscopic loads on the turbine and supporting tower. In order to resist these loads the structure must be heavily built. This increases the weight and cost of both the turbine and tower. The two blade teetering rotor virtually eliminates these large gyroscopic loads allowing the weight and complexity of the turbine and tower structure to be substantially reduced. The teetering rotor hub allows the turbine to run as smooth and vibration free as any 3 bladed turbine.
Advanced Rotor Design. We have often been complemented on how attractive our turbine is, especially the rotor blades. It is a perfect example of form following function. The blades were not designed to be attractive. The design was based solely on achieving the best aerodynamics. The Aerostar 6 Meter blades use AS 200 proprietary low reynolds number airfoils developed by Aerostar. The airfoils are optimized to produce energy at low wind speeds. Some turbines use untwisted rectangular shaped blades, sometimes called "constant chord" blades. The primary advantage is lower cost. Unfortunately, performance can suffer. Becase the speed of a turbine blade changes with the blade radius, optimum design requires the width of the blade to vary. Inner portions of the blade move slowly so they need to be wider to extract energy from the wind. Outboard blade sections travel at high speed so they can be narrower. The angle that the wind makes with the blade also changes with blade radius so, for a blade to be efficient, it must be twisted. Sections near the root need much more twist than sections near the blade tip.
Aerostar 6 Meter blades are made from advanced composites for high strength and light weight. Each blade set is matched by being made from the same mold so that the blades are identical and perform exactly the same. Many wind turbine blades travel more than 125 MPH so over time, rain and airborne dirt act like a sandblaster wearing away the leading edges. The leading edges of the blades are coated with a special impact resistant urethane so that rain and flying dirt bounce off saving the blades from erosion.
Advanced Rotor Design
Aerodynamic Rotor Control. Safety is the most important consideration when evaluating wind turbines. Experienced turbine designers and European turbine certification rules all require that there be some means of limiting rotor speed by aerodynamic control. Mechanical, electrical or hydraulic brakes should never be depended upon as the sole means of stopping a rotor. Although the Aerostar 6 Meter does have a fail safe stopping brake, the rotor is designed with articulating blade tips which automatically activate and slow the rotor if the RPM exceeds a certain value. The blade tips turn and provide aerodynamic braking. By articulating the tips, the useful area of the rotor is also reduced, further limiting rotor energy. This is the same type of system used on many large wind turbines installed all over the world. The system is completely automatic and not dependant on an external source ol power, which could fail precisely at the time when it was needed.
Aerodynamic Rotor Control
Induction Generator. Many small turbines use variable frequency alternators. Because the voltage and frequency of the electricity generated by these turbines varies with wind speed, the electricity they produce is incompatible with the utility grid. The power must be conditioned with an inverter before it can be interfaced with utility power. Inverters are complex, expensive and, oftentimes the most vunerable trouble prone component of a wind turbine installation. Induction generators are very similar to the induction motors which are used almost exclusively on every piece of rotating electrical machinery being produced today. They are simple, robust, reliable, efficient and trouble free. Because induction generators contain no solid state components, they are not subject to voltage transient such as lightning, which can easily damage the sensitive electronic components of an inverter.
Generator Excitation Control. All generators require magnetic excitation in order to produce power. The excitation required for an induction generator comes from the utility grid. If the generator and generator controls are not carefully designed, the excitation losses can substantially detract from power output of the turbine, particularly at low wind speeds when there is very little energy available in the wind. Aerostar has solved this problem by designing a control system that monitors wind conditions and reduces excitation losses at low wind speeds, greatly increasing energy capture.
Simple Control System. All Aerostar wind turbines use induction generators so there is no inverter. This makes the control system simple and robust. Interfacing with the utility company is simply a matter of connecting 3 wires. In fact, the control box can be plugged into an ordinary electric stove outlet. It doesn't get much simpler than that. At the same time, the control box gives you complete control over the turbine. When the lever switch (lower left corner of the box) is turned to the right, the turbine will be in the fully automatic mode. If there is enough wind the rotor will come up to speed and begin generating. If there is too much wind - more than 50 MPH - the system will shut down and automatically reset when the wind speed decreases. If you ever want to stop the turbine, simply turn the lever to the left and the brake will gently slow and stop the rotor. It will remain locked until you decide to put it in automatic mode again.
The control box has a large panel meter that shows how much power the turbine produces. There are indicator lights to show that utility power is available and when the generator is connected to the grid. The backlit LCD display shows the wind speed, wind gusts and generator RPM. There is an optional provision for a web interface so you can monitor the turbine from your local wired or wireless network. You can also upgrade the standard control box with a digital multifunction meter that shows power, kilowatt hours produced, power factor, volts, amps. and just about every type of electrical and power quality measurement in existence.
Color Touchscreen Display
NEW COLOR TOUCHSCREEN DISPLAY. All of our standard control boxes now include a color touchscreen display. The display includes a number of preconfigured screens that will provide you with the information that you need to know about the operation of your turbine. If you decide you need additional information, as a custom order, we can even customize the display to meet your needs. Standard screens include the following: 1. KW, Windspeed and Generator RPM. 2. Max values such as maximum wind speed, maximum kW and maximum generator RPM. 3. Average values for the last 10 minutes and the last hour, including average wind speed, average kW and average kWH. 4. Turbine set up parameter such as cut-in RPM, cut-out RPM, shut down wind speed, etc.
You can also opt for a special digital kWH meter that is capable of measuring the kW of the turbine, kW usage of your house and the kW that you feed back into the grid. This option will store an entire year's worth of data and let you look back to see how much power you produced, used or sent back into the grid on any date or between any two dates. You will also be able to recall average wind speeds for these periods. All of the information is shown on the color LCD touchscreen.
Another option that is available is an ethernet module that will allow you to view data such as wind speed and kW output in real time on your computer, any computer on your network or even from work if you have a static IP address. Another advantage of this option is that we can upgrade your control software from our factory at no charge to you so you will always have the latest software available. The ethernet module also has an email function that can send anyone an email if there is a problem or if you just want periodic emails sent to you giving the day's performance of the turbine.
