How to connect 4 micro turbines together?

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Wezelenburg
Wezelenburg Registered Users Posts: 3 ✭
in Wind Power Generation #1
Hi,

I am new here and are trying to support my solar system with a some wind power.

My plan is to connect the 4 micro turbines to a grid tie inverter.

- The inverter has an input DC voltage working area from 50-450V
- The 4 micro turbines are 24V/500W but without a controller so a pure 3-phace AC output where the voltage follows the RPM. 

I tested one micro turbine through a rectifier and the voltage output was 0-70V 

But how do I connect it all?

I tried connecting it like this below but I don't seam to get it to work, it is like one or two turbines stop rotating when others run. When I disconnect 2 of them they run better. Also I am not getting close to the amount of output that I should, could they infect each other. I hope someone can help.

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  • BB.
    BB. Super Moderators, Administrators Posts: 33,457 admin
    #2
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    Welcome to the forum Wezelenburg.

    What you are trying tro do in your drawing will not work for several reasons:

    1. In series, each turbine needs to produce the same current (Amperes)--And the micro turbines will, most likely, not all rotate at the same RPM at the same time. Meaning that each turbine will be outputting its voltage and current without respect to the other turbines. Similar issue to connecting all the turbines in parallel.

    2. In general, a typical Grid Tied (GT) inverter has an MPPT (maximum power point tracking) DC input. More or less, the MPPT input controls the input current drawn from a turbine and "adjusts" the GT inverter's input current to load the turbine to an optimum output voltage...

    Basically trying to solve the equation Pmp = Vmp * Imp ... Looking for that operating point to maximize that equation.

    With turbines in series, or in parallel, the MPPT input cannot maximize the turbine's RPM/Voltage/Current because each turbine is operating under its own conditions.

    SMA made some very nice "Windy Boy" GT inverters, but they got out of the market in 2013 because the government (various countries) subsides for small wind (less than 1.5 kWatt?) were going away.

    https://www.sma-sunny.com/us/sma-to-part-ways-with-windy-boy-inverters/

    In my humble opinion (I am not a fan of small wind), I believe this is because the small wind turbines available (at the time, and probably no better now) did not work. They either flat out did not work, or broke in less than a year, or never produced any appreciable/useful amount of power. Typically a combination of design/mfg issues, and choice of locations (i.e, city/suburban areas, parks with trees, etc.--All sites with poor wind, obstructions, and lack of laminar airflow unless mounted on very high towers--Which nobody wanted).

    The results of testing all showed that one large/utility sized turbine on a tall tower, in open fields, and based on actual measured wind conditions over time, was worth 10-20x of the smaller turbines. We have a thread from ~2009 discussing the test reports of some small wind turbines in Netherlands (some links are probably dead now, but there are others that are still good... Report was in Dutch, but Google Translate works fine on websites and even PDF files--Although graphics may not be "pretty").

    https://forum.solar-electric.com/discussion/3638/small-windpower-a-scam-survey-says-so/p1

    In any case, I believe (understand?) that you will need a separate GT inverter for each micro turbine to generate any useful/reliable amount of energy.

    I highly suggest that you measure the wind speed at the turbines themselves and see if it is fast enough to generate the power you expect. And that the wind is non-turbulent or laminar flow. Usually that means a 10 meter tower at least.

    If you have trees in the area, look for "flagging" of the trees from prevailing winds.


    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • Wezelenburg
    Wezelenburg Registered Users Posts: 3 ✭
    #3
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    Hi Bill,

    Thank you very much for the answer.

    I see the problems that you are talking about. Some of my thought about the turbines small vs large is goverment regulations here in my country. A turbine with less than 1.13m in diameter is not regulated. My home background consumtion is about 600W so I was trying to get that down with maybe 50-75% with 4 small wind turbines.

    My idea was that the inverter works from DC 50-500V with nominal voltage 350V and a max 13A, with that each turbine only needs to produce 12-13V to get the inverter to start producing power and in high wind condition I could get 4 x 70V DC and still be within the inverter working envelope.

    If it was possible to get all turbines to get close to the same RPM would it then maybe work?

    I tried to connect 2 parrallel circuits with each 2 turbines in series, but like you talked about, one will spin fast while the other will slow down, if i force the one that spins fast to slow the the other one will spin up.

    Is it a solution to maybe use a battery and 4 wind charge controllers to get the turbines to work independenly? Then the problem will be to get the power from the battery to the inverter, I have no idea if it would work but maybe have an DC to DC converter?
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  • Wezelenburg
    Wezelenburg Registered Users Posts: 3 ✭
    #4
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    Just to leave a little update

    The inverter is an 
    growatt mic 2000tl-x




    The 4 wind turbines are these
    https://www.banggood.com/800W-Peak-6-Blades-12V-or-24V-or-48V-Horizontal-Wind-Turbine-Generator-Residential-Home-Wind-Power-Generator-p-1289825.html?gmcCountry=DK&currency=DKK&cur_warehouse=CN&createTmp=1&ID=517271&utm_source=googleshopping&utm_medium=cpc_pt&utm_content=meruem&utm_campaign=aceng-pmax-dk-en-all-220602-meruem&ad_id=&gclid=CjwKCAjw8JKbBhBYEiwAs3sxN_4J9Rcr5ogHHgdPQbCH5eUvIaVMJ45MNcrwx5VRZFKRA5DucrMUGhoCjaMQAvD_BwE

    It is the 24V model, not that I think they are different when it is without the controller.

    And lastly this is the rectifier 100A version.

    https://heschen.com/es/products/heschen-sql-100a

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  • WebPower
    WebPower Registered Users Posts: 73 ✭✭
    #5
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    You should characterize your inverter. Spec sheet says 50v turn on. Where does it clamp the voltage at when "on?" See what it does at different supply currents. Your using 24 v turbines. They will get to 50+  volts when not loaded but nowhere near 50 under the load of an inverter or battery. Also, how long does it take to turn on? At what voltage does it turn off? Wind turbines don't play well with inverters designed for solar. You need some kind of interface. Even though my circuit clamps at 16v or so when on, a 48 volt turbine provides more consistent power than a 24v turbine. The 24v turbine has to be spinning faster to turn my inverter on. 

    I finally got my 500w turbine up tonight. If you look at my postings it's connected to an enphase microinverter. This turbine is a 5 blade 500w 48 volt. I'll post some numbers from bench testing it. I'm hoping it has better low wind performance than the 3 blade version. You will I believe have the best luck with an inverter for each turbine, but not the with inverter you listed.

    Good luck. Pat
    9000+W grid tied IQ7 22 panel rooftop and 6 panel ground combination with 1 additional IQ7 connected to 500W wind turbine+200w solar+2 IQ7s with 300W+600W on the RV grid tied when it's in the driveway.
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