2kw on grid

[Ulf Hansén]

Here is my 2kw generator with the Aurora 3.6 kw grid inverter and my
own made manoeuvring box to comply with the grid owner rules. It includes
voltage and frequency control.
Voltage control for protection of the generator, I used the solution from Cor Van Houtum
Lightning protection
Time relay for restart in strong winds.
If grid failure no automatic restart (grid owner demand)

Since middle of October I have got 388kwh and a lot of fun.

I will thank Cor for providing the Aurora inverter and great service and patient with my questions and all you in this forum for tip and tricks
Ulf
control box is up side down

[Rob Beckers]

Looking good Ulf! :cool:
What wind turbine is this?

-RoB-

[Ulf Hansén]

It is a chinesee one, Exmork but I think that is just a trade mark.
I have "pulled out" over 3.5 kw before I installed a voltage relay to brake it down.

[Wolfgang Wan]

Looks good performence from this unit. How much you have this from China? Total cost including transportation.

Thanks
Wolfgang
Zytech Aerodyne (http://www.zytechaerodyne.com)

[Ulf Hansén]

I don't now about the performance I have nothing to compare with. I have an advantage to live on a small hill that is quite windy the generator wasn't to expensive, its a bigger cost in the inverter/controller, as usual you get what you pay for.
This is a hobby project I'm just glad to have it working and its satisfying to make some own kW. Thinking about complete with solar heaters.

Ulf

YouTube- P1010709.MOV

YouTube- vindsnurra

[Cor van Houtum]

Hello Ulf,
I was happy to help you
why do you have a helmet on
is it that cold now in Sweden ?

[Edgar Paternina]

Here is my 2kw generator with the Aurora 3.6 kw grid inverter and my
own made manoeuvring box to comply with the grid owner rules. It includes
voltage and frequency control.
Voltage control for protection of the generator, I used the solution from Cor Van Houtum
Lightning protection
Time relay for restart in strong winds.
If grid failure no automatic restart (grid owner demand)

Since middle of October I have got 388kwh and a lot of fun.

I will thank Cor for providing the Aurora inverter and great service and patient with my questions and all you in this forum for tip and tricks
Ulf
control box is up side down

Hello Ulf,

I installed a Chineese 2kw-grid tie system too, a Yueniao one, but yesterday I had a big problem with very high winds that I want to share. See the attachment.

Fortunately the Aurora is a great inverter that records all its behavior, see the attachment!!!

1. In it we can find that from 10:49 to 11:26 the grid was off. During 11:27 to 11:33 a moment of very high winds I ask who consumed all this power?

2. At 11:34 the wind generator went off in spite there were high winds to 11:50.

3. When the grid entered again at 11:51 the wind generator started working relatively low as there were more wind that the DCV shown, please note that I have an independent wind measurement instrument.

4 At 11:56 the wind generator went off and did not enter again.

5. NOW IT IS OFF AND CAN NOT ENTER AGAIN. WHAT HAPPENS?

It is certainly the same kind of problem I had with my Kipor IG backup generator and the need to have another dump load controller when the grid is off to consume the excess of power.

Today I will continue having fun by putting down the wind generator to investigate what happens, fortunately I have as a backup my great Kipor inverter generator!

Best regards

Edgar

[Edgar Paternina]

Hello Ulf,

I installed a Chineese 2kw-grid tie system too, a Yueniao one, but yesterday I had a big problem with very high winds that I want to share. See the attachment.

Fortunately the Aurora is a great inverter that records all its behavior, see the attachment!!!

1. In it we can find that from 10:49 to 11:26 the grid was off. During 11:27 to 11:33 a moment of very high winds I ask who consumed all this power?

2. At 11:34 the wind generator went off in spite there were high winds to 11:50.

3. When the grid entered again at 11:51 the wind generator started working relatively low as there were more wind that the DCV shown, please note that I have an independent wind measurement instrument.

4 At 11:56 the wind generator went off and did not enter again.

5. NOW IT IS OFF AND CAN NOT ENTER AGAIN. WHAT HAPPENS?

It is certainly the same kind of problem I had with my Kipor IG backup generator and the need to have another dump load controller when the grid is off to consume the excess of power.

Today I will continue having fun by putting down the wind generator to investigate what happens, fortunately I have as a backup my great Kipor inverter generator!

Best regards

Edgar

Hello Everyone reading along,

Well the problem that I had was with a ball bearing that failed, I'll replace it and I hope everything will be working again quite good.

Best regards

Edgar:rolleyes:

[Ulf Hansén]

Glad to hear that.
I have notice that the gen,inverter(connections) is sensitive to moist and that give me ground fault.and the inverter went on and off. Cor gave me that tips to me out and I found moist in one of my temporary extension cables.

How many kwh are you getting from your generator?
Regards
Ulf

[Edgar Paternina]

Glad to hear that.
I have notice that the gen,inverter(connections) is sensitive to moist and that give me ground fault.and the inverter went on and off. Cor gave me that tips to me out and I found moist in one of my temporary extension cables.

How many kwh are you getting from your generator?
Regards
Ulf
Thank you Ulf! It was producing about 60 to 90kwh a month as an average as just recently I was having good winds, I mean in January, see the best day of it, on the 21st. It seems that you have had 6m/s of average winds too.

In February it started very very windy and then it failed. December was a very bad month as there were no wind.
This curve of the attachment was taken with the beta-communication of the Aurora I downloaded in site given by Rob. It has been very helpful as it permits to follow the behavior minute by minute, but as a beta it has some problems when starting a new day, sometimes I have lost the curve of the day before, if there were no wind at midnight.

Just want to comment something about the altitude. I am 2570meters or 8400 feet high and according to the theory this was going to be a bad place for that density of air issue, but I really have not noticed that bad behavior, I thought it was going to be worse. I don't think the problem of the bearing has to do with it!

Regards

Edgar

[Ulf Hansén]

Internet is fantastic I still get surprised over the possibilities to communicate this way

I didn't get any curve from exmork, I don't thin he couldn't get one.
My gen I ordered to give 2kw when 350v and I have just used try and error method
at first I have to steep curve and it did not accelerate. Maybe someone else have some tip but It seems hard to get out power in lo voltage I dont now if it is worth the effort
Half the fun is to get it working but it would be nice with a wind tunnel.
I haven't got the aourora communicator interface to work only the installer

Ulf

[Ulf Hansén]

Hello Ulf,
I was happy to help you
why do you have a helmet on
is it that cold now in Sweden ?

No Its protection for wings falling of!
How is it going with the 61400 ?
I have many asking questions but I really don't no what to do about selling
Nice weekend Ulf

[Rob Beckers]

Hi Ulf,

If you give me a bit more information I can probably make a proper MPPT curve/table for your turbine. If the manufacturer publishes information about rated power, at a rated windspeed, and rated voltage (AC or DC) that will help. Also the exact diameter of the turbine is needed. If you don't have rated power/voltage/windspeed I would need to know design TSR of the blades, and something about the alternator (RPM vs. voltage).

-RoB-

[Edgar Paternina]

Internet is fantastic I still get surprised over the possibilities to communicate this way

I didn't get any curve from exmork, I don't thin he couldn't get one.
My gen I ordered to give 2kw when 350v and I have just used try and error method
at first I have to steep curve and it did not accelerate. Maybe someone else have some tip but It seems hard to get out power in lo voltage I dont now if it is worth the effort
Half the fun is to get it working but it would be nice with a wind tunnel.
I haven't got the aourora communicator interface to work only the installer

Ulf

Well in my case the Aurora engineer asked for a DCV vs Power curve, and finally when the controller I bought from Yueniao was shipped, they gave me a DCV range from 100DCV to 400DCV and with this the Aurora engineer programmed the inverter. In fact now it starts producing power at 75DCV and it has a maximum of 400DCV, but with the average you gave as production, it seems your exmork wind generator is working similar to mine; on this Monday I saw 388DCV when I had the problem. The aurora communicator interface is connected through USB to a PC, and you can obtain the behavior of the inverter. Rob, can tell you where to download it, I am sure.

I am sure you will have much fun as I have done with it!

Best regards

Edgar

[Edgar Paternina]

Internet is fantastic I still get surprised over the possibilities to communicate this way

I didn't get any curve from exmork, I don't thin he couldn't get one.
My gen I ordered to give 2kw when 350v and I have just used try and error method
at first I have to steep curve and it did not accelerate. Maybe someone else have some tip but It seems hard to get out power in lo voltage I dont now if it is worth the effort
Half the fun is to get it working but it would be nice with a wind tunnel.
I haven't got the aourora communicator interface to work only the installer

Ulf
Hi Ulf and Rob,

Now it seems Exmork has available more information regarding curves and Power vs RPM, see:

http://www.exmork.com/2kw-wind-turbine.htm

I don't know if this is your same model, Ulf. Another way to obtain that data is with the aurora communication software.

I hope this helps

Edgar

[Rob Beckers]

Edgar, if I read Ulf's messages correctly he already has AuroraInstaller working with his inverter. That's all that is needed to program the MPPT table. I offered Ulf to determine a (better) MPPT table, though I'll need some turbine information to be able to do so.

-RoB-

[Edgar Paternina]

Edgar, if I read Ulf's messages correctly he already has AuroraInstaller working with his inverter. That's all that is needed to program the MPPT table. I offered Ulf to determine a (better) MPPT table, though I'll need some turbine information to be able to do so.

-RoB-

Rob, what I tried to suggest was that maybe both with the new turbine information in the attachment taken from the Exmork site, and the corresponding data obtained with the communication software, that MPPT table could be programmed easier, as I thought the MPPT table was sort Power vs DCV curve.

[Rob Beckers]

That's correct Edgar. The table is good (if they're not exaggerating power, as unfortunately many wind turbine makers do). It shows power out of the alternator, so for the MPPT table this needs to be converted to power out of the inverter (taking standby and efficiency losses into account). What's also needed is voltage vs. RPM, DC or AC. With that one can make an MPPT curve.

-RoB-

[Edgar Paternina]

That's correct Edgar. The table is good (if they're not exaggerating power, as unfortunately many wind turbine makers do). It shows power out of the alternator, so for the MPPT table this needs to be converted to power out of the inverter (taking standby and efficiency losses into account). What's also needed is voltage vs. RPM, DC or AC. With that one can make an MPPT curve.

-RoB-

Rob, let me make some supposition.

What about if we have both nominal RPM and nominal DCV, i.e., the data at nominal power, then we have:

k= RPM/DCV

this DCV can be measured or can be obtained with the aurora communication software if it has not been given by Exmork, and with this value then we can convert the RPM in the table to DCV, and there you have the MPPT curve, don't you?

[Rob Beckers]

Yeah, I just need a single point. Voltage at rated power is good (as long as I know what power/wind/voltage that is). For the calculations I assume there is a certain amount of internal resistance in the alternator, and voltage is not quite linear with RPM (as power ramps up too).

-RoB-

[Ulf Hansén]

Hi
I have been away on work so I haven't read this thread until now.
I be back tomorrow with some inputs
Thank you all
Ulf

[Ulf Hansén]

Best Rob and Edgar

The power curve that is on exmorks page now is a newer one with 3,8 m vings

my is rated
2kw 410 rpm 360vdc
2.8kw 510 rpm 600vdc

the inverter is programmed to bigger load after 370 vdc to star slowing it down but it just
put out more watts up to 3500w before I installed a omron voltage relay and a time relay that admits the generator to cool down for 20 min.
Here is the wind/power curve

[Rob Beckers]

Hi Ulf,

There are some discrepancies in the values: The Exmork docs list 2kW @ 10 m/s @ 400RPM @ 300V DC. You list 360V DC, that's a 20% difference (the 10 RPM difference doesn't matter). By the way, that 400 RPM gives it a TSR of 8, which is a bit high but quite usual for small turbines.

If 410 RPM is 360V DC, then 510 RPM should be around 445V DC (you're listing 600V). Alternators are close to linear in voltage vs. RPM.

So, if I assume your value that 410 RPM equals 360V DC is the correct one, and 2kW from the alternator happens at 10 m/s and 400 RPM, then the following MPPT curve should be pretty close:

Voltage Power
117 0
136 40
154 80
172 130
190 200
225 380
259 630
293 950
325 1400
356 1900
386 2500
415 3300
427 3600

Vin Start = 117V
Pout Ramp = 10000 W/sec
Tprot UV = 240 sec

Of course, if 400 RPM is 300V DC instead of 360V the curve would look quite a bit differently. If that's the case just let me know and I'll re-run the values.

-RoB-

[Ulf Hansén]

Of course its the 410 rpm/360 that is right I ordered the 350v (not listed on web page)
And its rated 400rpm/350vdc
Can you help me out with this things

Vin start I understand but what is Pout Ramp and Tprot UV ?

Vin Start = 117V
Pout Ramp = 10000 W/sec
Tprot UV = 240 sec


Regards Ulf

[Rob Beckers]

Hi Ulf,

Those are the other parameters at the bottom of the wind page in the AuroraInstaller program, see http://www.solacity.com/Docs/AuroraInstaller%20Manual.pdf, and scroll down to the screen shots on page 13. They are in the part that is marked as "3" on the screenshot.

"Pout Ramp" sets how fast the inverter should change power output due to wind/voltage changes. In general, the faster the better since that keeps the turbine better under control, and keeps it running closer to optimal load. That value of 10 kW/sec is as high as it'll go (after saving it, the inverter rounds it down to 9900-something, but it's close enough).

"Tprot UV" is how long the inverter should stay powered up after the voltage dips below Vstart. A short setting saves power, but means it takes time (and looses energy from wind) while the inverter reconnects to the grid after the wind comes back. A long setting keeps the inverter online longer, avoiding the numerous reconnection delays, but meanwhile it uses 20 - 50 Watt in idle power. A few minutes, ie. 240 seconds, is a good middle ground.

-RoB-

[Ulf Hansén]

Hi Rob thank you for this.
I am trying this table this weekend

Ulf

[Cor van Houtum]

Hello Rob,
About the Pout Ramp setting I am not realy in the clear here.

We have connected a big waterwheel to a 3kw generator
and true a windbox 4000 we connect the system to a PVI 3600 wind inverter.
what we see now is that the inverter is never satisfied with the input.
When we assume that the generator can do 1000 watts at a certain waterpower
and we put the table within range of the voltage and put just one pointer on
900 watts max the system works good.
this is because the generator can deliver more power as we ask.
BUT if we put a second curve point that is higher in power as the generator
can deliver with the present water flow then the waterwheel will start to ocillate.
the rpm starts to float up and down.
This gives enormes extra force on the spindle axis.

With a windmill you are never able to see this event from close but this waterwheel generator is grounded so we can study this thing.

It makes no difference if we change the voltage in the relation table
everytime it reaches max power it sems that the aurora wants to have more.
and the wheel is not able to give this power and ocillates.

Because the waterflow is not always on maximum it is not possible to put a good table insite the aurora.
it is just working for the moment.
when the waterflow decreases then the ocilation starts again.

It seems to me that between points the mppt tracking is not working and the aurora acts like a hungry pig :)

do you have any ideas

greetings

Cor

[Rob Beckers]

Hi Cor,

I've not heard of anything indicating that the Aurora is not interpolating correctly between MPPT table points.

To find out what is happening, can you log frequency, voltage (DC), and output power from the inverter. It has to be logged fast enough to show what's happening, so the log frequency has to be multiple times the oscillation frequency. Then send it to me, together with the programming you have in that inverter. That info should give a better insight, and show exactly what the inverter is doing.

-RoB-

[Rob Beckers]

Cor, I've been thinking what you said over a bit more...
If the inverters were truly 'a hungry pig' (I like that term! :weird:) the result with wind turbines would be to stall the turbine and result in very poor performance. We know that's not the case, so something else must be at play here. A water wheel may well have very different dynamics from the average turbine (even if both are ruled by fluid dynamics). I would really need that log information to be able to say something one way or another. You're well-equipped for setting up that kind of logging, so if you want to get to the bottom of this I'm certainly game, and will be happy to help as much as I can.

-RoB-

P.S. Maybe we should start a new thread about this though, since it has nothing to do with Ulf's turbine.

[Cor van Houtum]

Hello Rob,

I have made a different test and do not like the outcome
we have taken a 1000 watt series of solar panels and connected them to the aurora windinverter. (new one)
the output is reading then between 900 and 600 watts pumping
means occilating !!!

I have put the same solar string on to a pvi 6000 windinverter and
no problem it gives about 900 watts steady (when sun offcourse)

It seams to me that the algoritme of the mppt is not the same with 3600 and 6000

is there anybody out there who has seen this event ?

kind regards

Cor

[Rob Beckers]

Hi Cor,

You'll have to talk to tech support on that one then. We don't even have the PVI-3600 here, it was never released on the North American market (there's an old 3600 inverter, but that's different from the one you use, and no longer sold here either)....

-RoB-

[Cor van Houtum]

Thanks Rob,

I have put the question again to the tech people in Italy

ill keep you informed

[Ulf Hansén]

Friends
I have now used the inverter a couple of days with the new table in god wind
The first thing I noticed is that the generator runs more stable it doesn't go up and down in output.

Thanks
Ulf
ps good luck with the Italians Cor !

[Edgar Paternina]

Hi Ulf,

There are some discrepancies in the values: The Exmork docs list 2kW @ 10 m/s @ 400RPM @ 300V DC. You list 360V DC, that's a 20% difference (the 10 RPM difference doesn't matter). By the way, that 400 RPM gives it a TSR of 8, which is a bit high but quite usual for small turbines.

If 410 RPM is 360V DC, then 510 RPM should be around 445V DC (you're listing 600V). Alternators are close to linear in voltage vs. RPM.

So, if I assume your value that 410 RPM equals 360V DC is the correct one, and 2kW from the alternator happens at 10 m/s and 400 RPM, then the following MPPT curve should be pretty close:

Voltage Power
117 0
136 40
154 80
172 130
190 200
225 380
259 630
293 950
325 1400
356 1900
386 2500
415 3300
427 3600

Vin Start = 117V
Pout Ramp = 10000 W/sec
Tprot UV = 240 sec

Of course, if 400 RPM is 300V DC instead of 360V the curve would look quite a bit differently. If that's the case just let me know and I'll re-run the values.

-RoB-

Hi Rob,

There is a question I have always wondered. If the MPPT curve of Ulf's generator has been wrong all this time, then it means that its 388kwh obtained during all this period is wrong too?

Best regards

Edgar

[Rob Beckers]

Edgar, no, the energy measured is correct: It is the total that was fed into the grid over that time.

What the "wrong" MPPT curve will do is run the blades of the turbine at the wrong TSR. That means the blades will run at an angle-of-attack to the wind that is not optimal, and they will not produce as much energy as they could. Consequently, an optimal MPPT curve will keep the blades running at the best angle, or close to it, for all wind speeds (as in best lift-to-drag ratio). That maximizes energy production.

Most blade profiles are not all that sensitive to the angle that they run at, so the MPPT curve can be off, even by quite a bit, without having much effect on energy production. That is why a curve based on just the diameter and a few turbine parameters generally works really well. To actually make the best MPPT curve you would need to install an anemometer (preferably close to hub height), measure the turbine's power curve, move the MPPT curve up or down by a few percent, measure again, and repeat. That will show where the best power curve lies (output power vs. wind speed) for the turbine, and what the corresponding MPPT curve is.

-RoB-

[Edgar Paternina]

Egar, no, the energy measured is correct: It is the total that was fed into the grid over that time.

What the "wrong" MPPT curve will do is run the blades of the turbine at the wrong TSR. That means the blades will run at an angle-of-attack to the wind that is not optimal, and they will not produce as much energy as they could. Consequently, an optimal MPPT curve will keep the blades running at the best angle, or close to it, for all wind speeds (as in best lift-to-drag ratio). That maximizes energy production.

Most blade profiles are not all that sensitive to the angle that they run at, so the MPPT curve can be off, even by quite a bit, without having much effect on energy production. That is why a curve based on just the diameter and a few turbine parameters generally works really well. To actually make the best MPPT curve you would need to install an anemometer (preferably close to hub height), measure the turbine's power curve, move the MPPT curve up or down by a few percent, measure again, and repeat. That will show where the best power curve lies (output power vs. wind speed) for the turbine, and what the corresponding MPPT curve is.

-RoB-

Thank you, Rob, for such a beautiful explanation!


Then just another question:

then the MPPT curve has to do with wind turbine itself and not much with the Aurora inverter? It seems it can work with good results regarding energy with a wrong MPPT curve?

Regards

Edgar

[Rob Beckers]

then the MPPT curve has to do with wind turbine itself and not much with the Aurora inverter? It seems it can work with good results regarding energy with a wrong MPPT curve?


Correct. The MPPT curve has little or nothing to do with the inverter; once a curve has been made for a specific wind turbine it could be used with any MPPT type inverter or charge controller.

There is some overlap where the inverter plays a role: The way MPPT inverters work is that they want output power as a function of voltage (or frequency). That means the inverter efficiency needs to be taken into account for the MPPT curve. All inverters have voltage limits that have to be obeyed, and those can force the MPPT curve as well (for example, the turbine may have to run faster than optimal at the low wind speeds just to reach cut-in voltage of the inverter, on the other end of the curve, the turbine may need to spin faster than optimal to keep the maximum current below the limit etc.).

-RoB-

[Edgar Paternina]

Correct. The MPPT curve has little or nothing to do with the inverter; once a curve has been made for a specific wind turbine it could be used with any MPPT type inverter or charge controller.

There is some overlap where the inverter plays a role: The way MPPT inverters work is that they want output power as a function of voltage (or frequency). That means the inverter efficiency needs to be taken into account for the MPPT curve. All inverters have voltage limits that have to be obeyed, and those can force the MPPT curve as well (for example, the turbine may have to run faster than optimal at the low wind speeds just to reach cut-in voltage of the inverter, on the other end of the curve, the turbine may need to spin faster than optimal to keep the maximum current below the limit etc.).

-RoB-

Thank you Rob, I just want to tell you about my case. Initially I started conversation with Exmork to buy my wind turbine, but then the people of Magnetek -when they were distribuitors of Aurora inverters- demanded the MPPT curve of the wind turbine to program the inverter as they would not sell it to me without that curve, and as I could not obtain that curve from Exmork we stopped conversations, and I bought the wind turbine from another chineese supplier from which I just obtained, as it were, the Vmin_MPPT and Vmax_MPPT and the nominal data, with it I could extrapolate the corresponding curve I sent to Magnetek engineers, so you can understand the concern of my questions.

As a matter of fact, from the books by Hugh Piggott, I use this formula for tsr:

tsr = (RPM/WINDSPEED)x(3.1416x Diameter)/60

Best regards

Edgar

[Edgar Paternina]

Correct. The MPPT curve has little or nothing to do with the inverter; once a curve has been made for a specific wind turbine it could be used with any MPPT type inverter or charge controller.

There is some overlap where the inverter plays a role: The way MPPT inverters work is that they want output power as a function of voltage (or frequency). That means the inverter efficiency needs to be taken into account for the MPPT curve. All inverters have voltage limits that have to be obeyed, and those can force the MPPT curve as well (for example, the turbine may have to run faster than optimal at the low wind speeds just to reach cut-in voltage of the inverter, on the other end of the curve, the turbine may need to spin faster than optimal to keep the maximum current below the limit etc.).

-RoB-

Hi Rob,

Just another question-observation.

Normally in the information given by the Aurora communication software, the PDC1(DC POWER) and the PAC(AC POWER IN THE INVERTER SIDE), there is a difference that in some cases is about 6%, that does not seem to be ok. My question is: does it has to do with the need of a better MPPT curve?

Regards

Edgar

[Rob Beckers]

Edgar, yeah, the equation is correct (for metric units): TSR is simply the speed of the blade tips divided by the speed of the wind. The blade tips travel Pi * D meters each turn, and turn RPM/60 times per second, so they travel at Pi * D * RPM/60 meters per second. Now divide by wind speed in m/s and you have TSR.

The difference between input (DC) and output (AC) power of the inverter is determined by efficiency. This varies with the input voltage and power level. Normally (but not always) the Aurora inverter powers itself from the DC side, so most of the time the DC power will be greater than the AC power. Especially at low power levels this can be quite a difference as it takes a baseline amount (20 - 30 Watt) to keep the inverter powered. At higher power levels it should quickly climb to 94% or more, up to 96% efficiency.

Not sure why Magnetek required an MPPT curve to sell you an Aurora inverter. Maybe it was a requirement of their agreement with Power-One? I have no such limitation, if you want an 'empty' inverter I'll quite happily sell you one. Though these days I want to make sure that the customer actually knows what they get themselves into, so I don't create a support nightmare for myself. Having said that, the vast, vast majority of the time the customer simply supplies me the turbine details and I create a curve that's then programmed into the inverter before shipping it.

-RoB-

[Edgar Paternina]

Edgar, yeah, the equation is correct (for metric units): TSR is simply the speed of the blade tips divided by the speed of the wind. The blade tips travel Pi * D meters each turn, and turn RPM/60 times per second, so they travel at Pi * D * RPM/60 meters per second. Now divide by wind speed in m/s and you have TSR.

The difference between input (DC) and output (AC) power of the inverter is determined by efficiency. This varies with the input voltage and power level. Normally (but not always) the Aurora inverter powers itself from the DC side, so most of the time the DC power will be greater than the AC power. Especially at low power levels this can be quite a difference as it takes a baseline amount (20 - 30 Watt) to keep the inverter powered. At higher power levels it should quickly climb to 94% or more, up to 96% efficiency.

Not sure why Magnetek required an MPPT curve to sell you an Aurora inverter. Maybe it was a requirement of their agreement with Power-One? I have no such limitation, if you want an 'empty' inverter I'll quite happily sell you one. Though these days I want to make sure that the customer actually knows what they get themselves into, so I don't create a support nightmare for myself. Having said that, the vast, vast majority of the time the customer simply supplies me the turbine details and I create a curve that's then programmed into the inverter before shipping it.

-RoB-

Thank you Rob, yes, I think it was a limitation of Power-One to avoid that nightmare.

I have been really thinking in you to buy my future inverters, I hope very soon! Do you order them directly from Power-One?... so you can sell directly to a client in USA?

Best regards

Edgar

[Rob Beckers]

Edgar, yes, I get them directly from Power-One. We buy many pallet loads at a time from them. My business is their main distributor for Canada (I sell to both Canada and the USA though).

-RoB-

[Edgar Paternina]

Edgar, yes, I get them directly from Power-One. We buy many pallet loads at a time from them. My business is their main distributor for Canada (I sell to both Canada and the USA though).

-RoB-

Rob, if things go on as now, soon I will order my first Aurora inverters from you! My bad experience with the Yueniao controller has opened for me a whole world of friends that are very interested in my proyect and have been really helping me!

Regards

Edgar

[Rob Beckers]

What does the Yueniao controller do, other than rectifying 3-phase AC to DC? I was just looking at your older thread and the diagram in there; you already have an Aurora inverter, what would the purpose be of another one? Or are you planning to put up an Exmork turbine? How is the other controller working out, the Huangya controller?

-RoB-

[Edgar Paternina]

What does the Yueniao controller do, other than rectifying 3-phase AC to DC? I was just looking at your older thread and the diagram in there; you already have an Aurora inverter, what would the purpose be of another one? Or are you planning to put up an Exmork turbine? How is the other controller working out, the Huangya controller?

-RoB-

Yesterday, we changed the two Mosfets of the Yueniao controller, the ones that failed during a very high wind the 1st of February, so my system is in operation again today! That controller was supposed to support such a situation with dump load, but it didn't!

Yes, I have already an Aurora inverter, and the point is that we(me and my son in law) are thinking in making business in this field as there are already potential clients, around here where I live, and in the coast, in Cartagena, the city where I was born.

The Huangya controller, I have to test it yet, not with the system, but in another scenario, as I am not sure it will be safe! I don't want to take that risk!

The Kipor engine has been tested during low wind, and the Aurora accepted it as if the grid were on. In this experience with the Yueniao controller, I have been in contact with good electronic engineers and even friends that can design too such a dump load controller, both for the wind system and the Kipor engine.

Regards

Edgar

[Ulf Hansén]

Best Friends

Trying to explain my box

There are two parts of my box
Swedish grid owners do not accept The inverters own protection against over/under
voltage,frequency on the 230 volt " side"
And I have to build in some other things to.

The generator can not restart by it self,you have to open the box and push a button and if grid power goes out it have to short cut the generator.

To protect the generator I use Cors Idea with the omron relay but I have added
a time relay omron H3DS-AL that is connected to a ABB relay that is closed when no voltage. The ABB relay is connected to a brake resistor.
So the function is.

1. push the green on button and if grid voltage, frequency are within limits the big cont actor pulls and get a self hold and connect to the inverter.
2. If voltage is below 400 V (adjustable) the omron relay pulls and connect to the time relay that is adjustable between parts of sec up to many hours .
3. When time is up the ABB relay opens and disconnect the brake resistor.
4. Generator starts turning
5. if grid power is out of value or dissapear the 230 v contactor falls and shut down the generator because the K8 relay lose voltage .The generator can not restart by itself.
6. If its windy and the generator produce to many watts the K8 relay dropps and the ABB relay lose voltage and brake the generator, but now it can restart by itself after the time is up on the time relay.
7. Hope this make sense

Ulf

[Rob Littiken]

Best Friends

Trying to explain my box

There are two parts of my box
Swedish grid owners do not accept The inverters own protection against over/under
voltage,frequency on the 230 volt " side"
And I have to build in some other things to.

The generator can not restart by it self,you have to open the box and push a button and if grid power goes out it have to short cut the generator.

To protect the generator I use Cors Idea with the omron relay but I have added
a time relay omron H3DS-AL that is connected to a ABB relay that is closed when no voltage. The ABB relay is connected to a brake resistor.
So the function is.

1. push the green on button and if grid voltage, frequency are within limits the big cont actor pulls and get a self hold and connect to the inverter.
2. If voltage is below 400 V (adjustable) the omron relay pulls and connect to the time relay that is adjustable between parts of sec up to many hours .
3. When time is up the ABB relay opens and disconnect the brake resistor.
4. Generator starts turning
5. if grid power is out of value or dissapear the 230 v contactor falls and shut down the generator because the K8 relay lose voltage .The generator can not restart by itself.
6. If its windy and the generator produce to many watts the K8 relay dropps and the ABB relay lose voltage and brake the generator, but now it can restart by itself after the time is up on the time relay.
7. Hope this make sense

Ulf

Ulf,
Could you tell me the part # of the ABB relay that is connected to your brake resistor. I'm looking to use this same part in my system.

Thanks,
Rob L

[Ulf Hansén]

Hi Rob'

ABB
ESB 24-04
You have it on the pdf drawing earlier on the tread

Ulf

[John Szegda]

Hi RoB,

Upon reading this tread, I noticed the power curve you configured for Ulf is much different then the curve I programed in my 3.6 Aurora. When you have time, can you check my the following power curve. The 2kw Exmork has 3.8 meter blade and is a 300v
Alternator.

V P
100.00 0.00

160.00 89.00

200.00 236.00

240.00 410.00

280.00 650.00

300.00 945.00

315.00 1380.00

335.00 1870.00

340.00 2010.00

360.00 2463.00

390.00 3230.00

420.00 3564.00

450.00 3672.00


Pout Ramp 500.0

Vin Start 100

TPout UV 1

Vgrid N 245.0

[Rob Beckers]

John, those values you list are a bit strange as an MPPT curve. Power in the wind goes with the cube of the wind speed. To keep the TSR of the turbine constant (best lift-to-drag ratio in essence), the RPM of the turbine has to follow the wind speed linearly. Voltage is nearly linear with RPM. So, output power is nearly the cube of the voltage for an MPPT curve. There are factors causing it to deviate, particularly on the high end of the curve, due to changes in alternator efficiency, blade drag increasing at high RPMs etc. Still, it should look more or less like a cube function. Yours does not.

-RoB-

[John Szegda]

Hi RoB,

I got these figures from Exmork. How do you think the Turbine will act at high winds with this curve ?
Also can you run the correct numbers for me. As I mentioned, the Turbine is 300v with a wing span of 3.8m.

Thanks,
John

[Rob Beckers]

John, you can find the numbers I calculated earlier in this thread. Try running it with that MPPT curve and see what you get.

The curve you have puts a load of only 945 Watt on the turbine at 300V DC. According to Exmork's own documentation they should reach 2kW @ 300V. Now, I think 1900 Watt is more realistic at that voltage, but that's a small difference. Yours is a large difference. Underloading it means the rotor will keep speeding up until the voltage reaches a point there the combination of blade drag and alternator torque extract that 2kW, so your turbine will run much faster than what it would do with my curve. The curve I made runs the turbine at a TSR of 8, which is already on the high side (high RPM type turbine, and probably pretty noisy at higher wind speeds), yours runs it even faster.

-RoB-