Hello turbine enthusiasts.
At the risk of appearing that we are using this forum to promote our turbine I would like to take an opportunity to clarify a few points. Before though, I would like to say that I enjoy pouring over the information and topics of discussion on this board. When I found this forum last year I quickly realized that an induction grid-tie is drastically different then DC turbine also I am impressed by the level of knowledge and skill to be found here.
The first point about our turbine I would like to respond to is the power output statements that we have made and continue to make. Most of the information on our web site is written for individuals who probably do not have as much understanding of wind power as the folks who participate in discussion here in this forum. In an effort to make an issue "simple" it would appear to the informed that we are being deceptive when say that Breezy 5.5 will produce 2.1KW at kick-in with a wind speed of 6-8 mph.
Technically: when "Joe, (person interested in our turbine)" steps out on his back porch, raises his handheld wind speed meter and measures 6-8 mph wind speed he can be assured that Breezy will be just starting to cycle in and out of production. The turbine 60+ feet in the air is seeing approximately twice the wind measured on the ground. In addition I have programmed the controller to bring the turbine online far into "slip" which allows us it to take advantage of a turbine rotor weighing nearly 175 lbs and the inertia stored in it while the turbine operates in low wind speeds near the threshold of production. This is also a benefit gained by using the torque limiter in the drive system (and zero-cross interconnect relay). The power realized at this kick-in speed will be seen as 5 to 6 second bursts of power as the generator extracts the inertia from the turbine followed by 5 to 6 seconds of build up when the turbine is released from the grid at a balanced speed of 1800 rpm and again allowed to climb far into slip. As the wind speed increases to 9 mph and above there is power enough applied to the rotor to keep the generator above 1800 and continuous power is produced.
I would like to concede that total power produced annually is a hypothetical best case scenario. The wind speed data is taken from government wind study in our area and is accurate in what it is. The average is all wind speeds for our area (hour by hour). That means that all wind above 23 mph which will not result in more power output and of course all wind below 6-8 mph will not count at all. The actual data may be manually extracted hour by hour and compiled for the year to get a realistic picture of the turbines capability. Since there is pretty much a level playing field for wind turbine output comparisons (wind is wind) we're pretty much left with comparing turbine output per wind speed and density.
You have seen the pictures posted here by others and on our web site. If you are unfamiliar with some of the older commercial built induction generators (10 to 50KW) you may not notice the changes we have made. In our design we have moved the rotor away from the gearbox and placed it on its own large flange bearing. Almost all previous designs mounted the rotor directly to the gearbox, subjecting the gear box to all the vibration and shock produced by the rotor. The torque limiter and chain coupling serve to isolate the rotor from the gearbox, provide a slip-point for rotor shock and during shutdown. The material used in this design is equal to or larger then the 25 KW Carter (one of which still sits on an 80' tower at our test site, broken of course) from the ½" plate frame, 2-1/4" drive shaft, and right down to the 5/8 " steel cables keeping it upright.
Grid-tied induction turbine generators (in my opinion and I am biased) offer many advantages of their own. Being grid-tied it produces a replica of the sine-wave of which it is drawing as reactive current. That is, it is generating back exactly what it sees coming from the power company, on frequency, in phase, and at the proper voltage. And it does it all without inverters or batteries. Once "locked" to the grid (the generator rotor is magnetically locked to the rotating 60HZ field and resists all force to break it free) the induction generator is the primary control of the stall point of the turbine. That is, one can control the power produced by the turbine rotor by absolutely fixing the forward speed of the turbine blades (which is done for us automatically) allowing the frontal wind seen by the turbine to stall the rotor at just the point where our generator reaches maximum safe operation. Farther, the generator is locked to the 60HZ line freq. (or 50HZ) at a speed near 1800rpm, the generator is connected to the turbine rotor through a 14.55 to 1 gear reducer, so... the turbine rotor is (fixed) at a speed near 120 RPM and remains locked at this speed while in operation.
Basically micro-controller really just oversees the operation of the turbine. First, it controls the brake by releasing it on power-up and applying it if grid connection is lost or there is an over-speed condition detected (129 rpm rotor). Second, the controller uses a tach signal to energize the interconnect relay when the generator is above 1800 rpm and release the relay if shaft speed falls below 1800.
While Breezy 5.5 may not be indestructible (show us a turbine that is) it is definitely a brute.
The requirements from power companies have varied from none to the same requirements that a large megawatt wind farm might have to meet. Check with your power company to get and understand their application process. We'll be happy to assist with the process.
Alan and I continue of offer an open invitation to all who wish to see one of the turbines in operation. You are welcome to bring your own meters, etc. We only ask is that you call first so that we can schedule your visit.
