Windspot in Antarctic

[Marek Klon]

Finally I am sending one windspot turbine to polish arctic station Arctowski located in Antarctica
https://sphotos-a-lhr.xx.fbcdn.net/hphotos-ash3/q71/s720x720/535812_544914898895662_397319133_n.jpg

There are 3 diesel generators working 24/7 supplying energy to station (freazers, heating, lights etc ). Lowest station consumption is 30 kW.
The plan is to connect turbine to one phase of that 3 phase grid what exist there (phases are not equally loaded so will connect to a phase with highest load ).
The grid is small so it fluctuates a little sometimes within this range:
Frequency change from 48 do 52,5 Hz
Voltage 400 V +/- 5V

I am planning 9 m mast and 6kW power one inverter but my concern is will it work ? (I mean will inverter feed to that grid ? )

here is one more photo of location
https://fbcdn-sphotos-g-a.akamaihd.net/hphotos-ak-prn1/535812_544914895562329_660717182_n.jpg

thanks for any feedback and help.
Marek

[Rob Beckers]

Hi Marek,

Unfortunately that will not work. At least not with a Power-One inverter (and likely not with any other grid-tie inverter). The frequency requirements for grid-tie inverters are very strict, and to get UL/CSA/CE listing they have to disconnect from the grid when the frequency strays out of bounds. For our North American Power-One inverters the allowed frequency range is just 59.72 to 60.28 Hz. It will very briefly tolerate excursions outside this range, for example, at 59.38 Hz the inverter will disconnect when this exceeds 120ms., the further it strays the faster the inverter disconnects from the grid.

In other words, you need frequency stability of the grid it's feeding into within about +/- 0.25 Hz.

-RoB-

[Marek Klon]

thanks Rob
just found out that such a big frequency fluctuations occurs only when big loads are being connected (not very often ). I can accept that on this moments inverter will swith off. As generators are good quality they keep 50 Hz so I hope they should feed then.

Anyway I got that email from tech support power one

"Inverter doesn

[Shaun Burgess]

hi Rob , Marek.
so the goal is to reduce the fuel that the generator burns . Am i rite in saying that . Would it not be very low the saving . If the generator is running anyway the difference would be the engine running with a little less of a load. i wonder how much fuel is a lt in antarctica . I suppose every little helps

[Marek Klon]

small upgrade on this Antarctic project

turbine installed in December 2013 and since beginning did not have fluid for low temperatures in a hydraulic dumper (pitch mechanism ). Fluid never changed and at the end of winter (there) blades fell off... (In my opinion due to excessive rpm as one blade was 150m from the turbine ... also some malfunction of inverter reported at this time ).

Turbine is only on 7.5 m mast and in not best site (turbulent wind as it's just beside hill).
Few pictures (http://www.energyfreedom.ie/Projects/Arctowski) and few more (https://plus.google.com/photos/116413123506663905974/albums/6049760065448764257?authkey=CJKKl6nGvMiirwE)

turbine is working with sieb and mayer 5kW inverter on frequency vs power curve
https://lh4.googleusercontent.com/-624xeAJPico/VJVRFsG6ZrI/AAAAAAAABXk/teuJw8IoyaE/w897-h638-no/sieb%2Bkrzywa.jpg

Sieb and mayer inverter works in wide range of grid parameters and that works fine.

Turbine gave 80 kWh in 24 h (here (https://www.dropbox.com/sh/krsrepcwrv31293/AAAquHCLReTIcTHJT75GNYn_a?dl=0) data log we were able to download from aeocon - one of those files shows that 80 kWh per 24h )

now we have new sets of blades and proper stop switch for the turbine (with resistor in it ). I just wonder if I should change power curve to load the turbine more at 250 rpm ?
Sieb and mayer Hz vs Power curve shows that inverter loading turbine with 3037 Watt at 42.32 Hz (aprox 250prm ) and jumps to full power after that. I just think that it should be changed to full power at that Hz.

and what about Voltage vs Power curve ? which one is better ?
this one is from UK installer
https://lh4.googleusercontent.com/-srRzW7dJbSA/VJVTnvw5oMI/AAAAAAAABYE/UPxU9q5-AEg/w731-h533-no/aurora2.jpg


and this one is one of mines
https://lh3.googleusercontent.com/-FZbRmFHjYVw/VJVTlIwmn0I/AAAAAAAABX8/zCh-WP-PrrE/w770-h590-no/aurora1.jpg


Marek

[Rob Beckers]

Marek, I can't make the link to the power curve load (the one titled "photo"). There are two power curves in the pictures you link to from "few more", and if you're running those they are likely far from optimal. Power vs. frequency or Voltage should be (nearly) a cube curve (ie. frequency or Voltage to the third power with a scaling factor). It flattens off at the top since alternator losses start to mount (square of the current, causing heating of the alternator).

If high winds and the ability to control the turbine are an issue at the top end then purposely overloading the turbine once you get closer to peak power is one way to force the blades towards stall, and make it handle those gusts a bit better (a gust will stall the blades, generating less torque than it otherwise would). Of course, if this turbine uses pitch control and you loose that mechanism there's little to save the turbine...

You'll have lots of turbulence that close to the ground. No two ways about it. Being at the bottom of a hill will slow down the airflow, possibly as much as 50% (see this link (http://www.solacity.com/siteselection.htm)). Maybe that's not a bad thing if extreme wind speeds are one of the problems.

One of the issues we ran into with wind turbines here in Canada is that regular metals are not meant for use at temperatures below (about) -45C. Their structure changes below those temps, causing them to become very brittle and easily shatter. There are special metal compositions that go down further in temperature, those are not normally used though (and I would think it would also add quite the expense). Another one, that you already ran into, is that special greases and other lubricants need to be used.

Neat though to run a turbine in Antarctica! Buy me a return ticket and I'll come program the inverter! :blink:

-RoB-

[Marek Klon]

thanks Rob
I wasn't placing turbine there (actually I have showed location but they ignored it saying that it has to be there due to safety reasons - they were afraid of flying blades ). Site is not perfect and turbulence depends on wind direction - as you can see turbine made world record of production in 24 hours (80kWh ).
Thanks for suggestions regarding power curve and cold temperatures.
I'll get you ticket there when 5 more wind turbines will land there :)

greetings from Ireland
Marek

[Marek Klon]

here is some 2sec data collected via aurora manager
https://lh4.googleusercontent.com/-Vp1DxR2m444/VJc7his-l6I/AAAAAAAABYw/85kzhwwVWVw/w406-h861-no/krzywe.jpg

this is what power curve currently in
https://lh5.googleusercontent.com/-imXUBJjwyMY/VJc8FBjW4eI/AAAAAAAABY4/yREDc87aT0M/w399-h294-no/marka%2Bpower%2Bcurve.jpg

I am advising to insert full power of inverter (4kW in this case for aurora 3.6) at 400V, I wonder if that will improve those graphs to be less "over shooted from trend lines" ... also what Pout Ramp settings - what is should be ? any reason to make less W/sec than full power/sec ?

[Marek Klon]

looks to me like those power one inverters are not ideal ... I have been experimenting with different power curves recently and looks to me like strait line with Pout Ramp about 1500W/sec works best (at least in strong winds as that was times when I have visited turbine). Having steep sqare/qubical shape curve with Pout rate 4000W/sec was giving pure results as turbine was slowing down any time reached about 3.5 - 3.8kW (steep power curve there ) and inverter never hit his max power of 4.6kW within a month !

https://lh3.googleusercontent.com/-pWM0uCsTp-w/VLl76utfOLI/AAAAAAAABas/kWfB7qgBvKM/w1051-h631-no/ramp%2B4000.jpg

ten strait line from 200V to max power at 365V DC worked well but 500W/sec in this gusty wind was not enough getting dump load on often
https://lh6.googleusercontent.com/-zK4_9JX0G2k/VLl75-vrExI/AAAAAAAABag/WWl62wDRFnc/w965-h618-no/ramp500.jpg

finally strait line with 1500W/sec
https://lh5.googleusercontent.com/-0_mBbFz-tIw/VLl76c2aHjI/AAAAAAAABao/mvE3YKupqDo/w930-h641-no/ramp1500.jpg

I wonder how it will work in smaller winds on that "flat" power curve
have a look at the movie from yesterday's storm


SMA wind inverters have extra setting for PI control ... I think that's what's missing in aurora inverters

https://lh4.googleusercontent.com/-3PvHLf_JdI8/VLl-SMRWsOI/AAAAAAAABa4/DUkkxyj2YRU/w886-h546-no/sma.jpg

[Rob Beckers]

Hi Marek,

Interesting stuff! Thank you for posting.
What does the extra "KI-wind-req" setting of the WindyBoy do? I.e. what does it control?

The "Pout Ramp" setting of the Aurora inverters controls how fast the inverter responds to changes in Voltage or frequency (depending on the mode used). In general, you would want that to be a high value, for most turbines I've set it to 5000 Watt/sec, so that what the inverter does actually matches what the turbine does (rather than lagging behind). However, we've also found that the inverter has some dynamic behavior where it will oscillate in output power for high values of Pout Ramp.

In theory a cube curve would be the best match for optimally loading up a turbine rotor, however, rotors are not ideal, alternators are not ideal, so what works best for your particular turbine may well deviate. It's not all that hard to develop the ideal MPPT curve for a turbine though, if you have the ability to log output power vs. wind speed (preferably at hub height), the anemometer doesn't even have to be calibrated as all you're interested in are relative measures.

By logging wind speed vs. output power you get the turbine's power curve. Ultimately you want to optimize that: Get the most output power for every wind speed on the curve. Since energy is in essence the integral of that power curve (with time thrown in), maximizing the power curve maximizes overall energy harvest.

Just run the turbine with one curve for a while, plot there resulting power curve. Then change the MPPT values by, say, 20% in one direction and do it all over. Do the same again changing the MPPT values 20% the other way. Compare resulting power curves and it should be pretty obvious in what direction changes should be made to optimize things (and it may well be that the low wind speeds need changes in one direction, while the high wind speeds need changes in the other direction). Iteratively you should get to what is the best MPPT curve for your turbine.

Regarding the dump load, you want to keep that off as much as possible since it (generally) is a waste of energy. So if (over)loading the turbine at the high-end of the wind scale keeps it producing energy without switching on the dump load that is desirable.

-RoB-

[Marek Klon]

PI (http://stackoverflow.com/questions/23421987/formula-for-pi-regulation-proportional-integral-algorithm) regulation (or PID (http://en.wikipedia.org/wiki/PID_controller)) in my words is kind of clever regulation you need to use if you want to balance ball on the middle of the moving table ... do not move to fast, move gently according to moves of the ball ... so smaller ball and bigger ball can be hold on the table etc ...
I have try this power curve with SMA 3300 inverter and Fortis wind turbine today
https://lh5.googleusercontent.com/-3RR7kDl7tMo/VLwnop4iZSI/AAAAAAAABc8/SIXfTFto7Pc/w845-h619-no/krzywa%2Bfortis1.jpg
looks much better holding curve than power one ... but wind was also less turbulent and not very windy (more (https://plus.google.com/photos/116413123506663905974/albums/6105798530653736081) pictures)

[Cor van Houtum]

looking at your movie
I am sure that your curve is not optimal
at 400 volt you should hit 4200 watts on the windspot.
otherwise it pitches every time
see your movie and you will see also max power drops off more then 1000 watts
and spins up again

kind regards
Cor