Is This a Single Bladed Wind Turbine?

[Jacob Rojas]

Hello guys I'm new to the forums. I have some questions mainly about loading a generator but first I would like to ask everyone's opinion about a new design and if it is a one bladed wind turbine. It has a 220ac generator full wave rectified to 24 dc. At 4ms wind it makes 7 volts.

It's called T-Vawt Crow (https://drive.google.com/file/d/1hcl133BYIQTvzhJn_T_rESuZG7NrfGPb/view?usp=drivesdk). Video link (https://drive.google.com/file/d/1Bw6g3lLVpZF1RcRJmF4-aIgOuwn31iUZ/view?usp=drivesdk)

[Rob Beckers]

Not sure what that is Jacob...

This is a single-bladed wind turbine: http://aerotrope.com/what-we-do/wind/wind-turbine-design-case-studies/riva-calzoni.html

-RoB-

[Jacob Rojas]

Thanks Rob. Can you please tell me the proper ohms to use to load a 1.5kw generator for test? Ive been very confused trying to find the resistors online. I read 100ohms is used? What actual resistor is it because the only ohms resistors I know of are the smalls ones.

[Rob Beckers]

Jacob, the value of a load resistor depends on the Voltage the generator produces. The Watt (in heat) dissipated by a resistor is equal to:

P (Watt) = U x U (Volt) / R (Ohm)

turning this around:

R (Ohm) = U x U (Volt) / P (Watt)

So, for a generator that produces 250 Volt and 1500 Watt, a resistor of 250 x 250 / 1500 = 41.7 Ohm will do the job. With 1.5kW this will NOT be a "small" resistor...

-RoB-

[Jacob Rojas]

Again I appreciate your reply Rob. Can you give me an idea what this resistor would look like? This would be a load resistor for test not for dumping.

[Dave Schwartz]

There's no resistor in that power rating of that resistance but it would work to put two 1000 watt 82 ohm resistors (https://www.digikey.com/product-detail/en/te-connectivity-passive-product/TE1000B82RJ/TE1000B82RJ-ND/2367702) in parallel. They're about a foot long and 2.5" in diameter, surprisingly only USD$48.98. You would probably want to employ fan-forced cooling because its going to be like a space heater on high.

https://media.digikey.com/photos/TE%20Connectivity/1-1879453-3.JPG

[Jacob Rojas]

Dave,

Thanks alot for the info. That resistor is it used to stop the turbine or just slow it down? My goal is to show how much voltage the wind turbine makes under load in a live test. Im hoping with the loaded/unloaded test we can show how much of a larger generator can be mated to the wind turbine chassis. I had found these resistors (https://www.mouser.com/productdetail/ohmite/teh100m20r0je?qs=sGAEpiMZZMu61qfTUdNhGx%2FMhSLX4N0 m7cv%252bDp8uHOI%3D) but I guess they could not affect the output? Our next test is the 10th here in Korea so I need to find the proper resistors here.

I want to be able to show 4ms wind = 6volts dc no load and then maybe 4ms wind = 5 volts @ 100ohms/500watts resistance. With the difference in performance under load we would be able to supply some pretty good live test numbers and estimate how large of a generator we can facilitate with this new design.

[Dave Schwartz]

I'm not a wind power expert.

Depending on how you are going to supply the input motive power to the generator under test you might be better off creating a variable load. The trick is to not have such a great load that the generator can't start but be able to increase the load demand up to your driving power capacity. Real generator manufacturers probably achieve this with a huge rheostat but you may be able to do something similar by switching individual smaller resistors like the 100w ones you reference in parallel.

The controller's trick, informed by the power map, is to match the load to the input voltage (which depends on wind speed) to allow the generator to remain within its operating range.

[Jacob Rojas]

Guys,

Thanks for the info. I went out shopping to the components area here where I live and was able to get 4 100watt X 50ohm resistors. I did some research and I wanted to confirm that when I hook 4 of these 100watt by 50ohm resistors together in parallel the actual resistance will be 400 watts by 50 ohm? I was going to wire the control box so that each switch closed the circuit for 1 more resistors.

I can understand the importance of the watts resistance since it slows down the turbine but I am unsure of the effect the ohms restricts. I had read somewhere 100ohms is a good goal but I'm not even really sure of that importance.

So on one part if I were to put 3 in parallel and the last in series would that be around 80 ohms and 400 watts Resistance?

[Rob Beckers]

Jacob: http://www.electronics-tutorials.ws/resistor/res_5.html

"Give a Man a Fish, and You Feed Him for a Day. Teach a Man To Fish, and You Feed Him for a Lifetime"

Forgive my harsh remarks, but your questions reveal a somewhat disturbing lack of understanding and basic knowledge of (wind) turbines, physics, and the most basic of electronics. By itself that's not so bad, it's an opportunity to learn. However, you will not get the results you're looking for unless you actually understand what you're doing, and so far you've only been asking others to do the thinking for you. Sizing resistors is so basic that you could (and probably should) have learned that for yourself by now.

Hooking up a bunch of resistors won't get you a happily running turbine. As others pointed out there's the problem of startup with a load on it, more disastrous is that power from the turbine increased with the cube of the wind speed while the load posed by the resistors only goes up with the square of said wind speed (and the Voltage from the alternator, which is at best linear with wind speed). The end result is a very good chance of runaway and self-destruct. Just don't be anywhere near the thing when you're testing, at 1.5kW+ output there will be plenty of stored energy in inertia and such to do real damage.

Resistors are used with wind turbines as dump loads, to keep it under control at the top end of its output. At that point they are sized to walk the fine line between overloading the turbine and not burning out the alternator. The overloading is needed, essential in fact, to slow down the blades to the point where they aerodynamically stall, and the wind looses its 'grip' on the blades so the load can keep them under control, and keep the rotor from speeding up any more.

-RoB-

[Jacob Rojas]

Rob,

I hope you can understand that I literally know nothing about loading a wind turbine for test. I've searched online all over for this information of how others do it and really have been unable to find anything. This forum is basically my only option. I am simply trying my best to test a design that I have developed however I don't know the rules of this particular fields as far as what I need to show (loading-wise) for proof of concept.

I hope you all can understand. I have spent many hours traveling to get correct parts and researching/testing the best I can but this field is very new to me in regards to what the industry needs to see for proof of concept.

[Rob Beckers]

Jacob, OK, here are some basic 'edificational' links:


How wind turbine blades make power - by Hugh Piggott (http://www.scoraigwind.com/wpNotes/bladeDesign.pdf)
Paul Gipe's site, with many good articles on wind turbines (https://www.wind-works.org/cms/)
Paul Gipe's "Wind Power" book, a great resource! (https://www.amazon.com/Wind-Power-Revised-Renewable-Business/dp/1931498148/ref=sr_1_1?ie=UTF8&qid=1515529238&sr=8-1&keywords=Wind+Power%3A+Renewable+Energy+for+Home%2 C+Farm%2C+and+Business)
The Back Shed, another good place for info (http://www.thebackshed.com/windmill/Contents.asp)


To my earlier point though, the very basic stuff such as parallel/series resistance is something you can (and should) very easily find by yourself with just the most simple of Google searches.

Even from the perspective of viability it makes sense to educate yourself: You may be spending a great many hours on something that has been tried before. When it comes to turbine blades people have come up with a great many variations already, not all sensible, and an understanding on why/how turbine blades extract power from the wind would help you make the decision on design viability early on.

-RoB-