aurora 3,6 with generator 120vac

[Robert Bilski]

Hello. Thank you for helping to reactivate my Aurora 3.6 inverter. The fun with photovoltaics ends on the tracker I am building. I always wanted to have a wind farm working properly and since now I have a wind inverter I would like to run a forgotten project complete set FD3.6 2000 120VAC. Will the generator's 120ac voltage, or approximately 165 dc nominal, be well supported by the inverter? If possible, please help me calculate the power curve. 120v, 17a, 2000w, 400rpm, 3.2m rotor, 9m / s. I am using google translator for which I apologize. greetings

[Rob Beckers]

Hi Robert,

So you managed to convert a solar PV Aurora into a wind inverter with the posted instructions? If so, great! I was waiting for people to try it and report back.

165V DC is no problem for the inverter, though you're working on the low end of the range and may run into the maximum current (won't damage the inverter, but will clip output power).

Have a look at your numbers, you can't have 2000W out for a 3.2m rotor at 9 m/s wind speed. Before losses, with good rotor efficiency, you would only generate about 1200 Watt coming from the rotor at that wind speed.

For an MPPT curve I need the exact diameter (3.2m), assuming it's a HAWT type turbine. and a point that links power, wind speed, and DC Voltage. That can be rated output power, or any other point. A point higher up on the power curve will help make the lower points more accurate (interpolating is more accurate than extrapolating). I can create power curves from more fundamental parameters for homebrew turbines, but that will require a lot more info.

-RoB-

[Robert Bilski]

Hello. I have never started this generator because the production is too small for heating and the controller is damaged. I bought a set for 300 USD where the cost of the mast itself is higher. And since you can connect to an inverter, the heat pump will multiply the profits will be fine. In winter, there is a lot of wind in my area and the photovoltaic produces little, so I want to start a windmill for the next winter. I gave the parameters from the documentation I have for the device, I know they are too good. I will attach a pdf with such a device, only the driver is different. greetings

[Rob Beckers]

Robert, looks like they may have moved the "wind speed" axis over about 2 m/s to make the turbine look better. Usually rated wind speed is around 11 m/s, and for the size turbine you have that would indeed produce around 2kW output. Assuming the 120 VDC is at 11 m/s and about 2 kW, you'd get the following MPPT points:


Wind (m/s) DC Volt Watt Out
3 37 2
3.5 42 26
4 48 58
4.5 54 98
5 60 149
6 71 283
7 81 470
8 92 716
9 102 1030
10 111 1420
11 121 1894
12 130 2460
13 139 3125


The Aurora inverter has a startup Voltage of 50 VDC, so values below that are irrelevant (and of little power). An MPPT curve to load in the inverter could be:


DC Volt Watt
50 0
55 100
70 280
90 700
120 1900
135 3000


The inverter startup Voltage should be set at 50 VDC.

The Aurora 3.6 inverter has a maximum DC input current of 32 Amp. Luckily this table keeps the currents under that, so the inverter can follow it.

Of course, with the sketchy info about your wind turbine this MPPT table is equally sketchy and may be utterly off.

-RoB-

[Robert Bilski]

Hello. The device was reworked according to your instructions, thank you very much. Regarding the limit value of 50-70 v inverter, you write about the possibility of connecting a resistor that causes a start from the voltage on the dc side. I understand that despite the set value of 50 v, the voltage drop on the resistor will cause proper operation. The device, in the absence of production, turns off and starts only when the dc voltage is appropriate and does not charge 40w when stopped. Thank you for the mppt tables, voltage 120 to ac generator, after rectification, the voltage will increase by √3, minus the loss on the diodes 1.4v. Will I multiply the whole table by √3 and everything should be fine? Earlier I wrote 165vdc but it's a three-phase generator and it seems to me that it comes out nominally 206.4vdc. Much better value for an inverter. With such values, it makes sense to install a dc tripping protection at 540vdc. I would limit myself to protection of power failure and power dump. Does the resistor value remain unchanged at this dc voltage? And the current will be safe, it will be reduced to 10A. Please judge if I think correctly. GREETINGS

[Robert Bilski]

Hello. I wanted to clarify, the problem is in the manufacturer's description because this set is actually 120Vac. I made a mistake twice, the first one did not write that on the generator nameplate there is a delta connection of 120 v [I guess ac], the second is the multiplier is not √3 but √2. I confirm the fact that I accelerated the rotor and measured the voltage after straightening and before and actually the value on the meter increased from 120v to 170v. The power value is the same in the wind speed function, I just change the voltage. Thank you for your help and sorry for the inconvenience, I can boast of the effects of my work in the fall. I am concerned
confrontation with reality because the production from wind, as I can see in others, looks very poor compared to photovoltaics. But it's not about money, it's a hobby. Regards

[Rob Beckers]

Hi Robert,

The spec sheet mentioned 120V DC, guess that spec sheet is about as reliable as the turbine!

The 3-phase AC-to-DC ratio is not quite √3 due to various inefficiencies. I've found a factor of 1.33 to work reasonably well in actual measurements. Of course, each case is different, and at the end of the the MPPT curve I can generate from these few parameters is just an approximation (though it turns out they work reasonably well in many cases).

Delta or Star connection of the windings doesn't really matter for AC-to-DC conversion. Either is just a 3-phase AC source, and you get the same DC.

If you have the parameters I mentioned in another post (today) I can do somewhat better in generating an MPPT curve.

-RoB-

[Robert Bilski]

Hello. I will try to get a complete set of information about the generator, only there will be a problem with the TSR. Probably not soon [no time]. greetings

[Robert Bilski]

Hello. Rob generator winding resistance is 2.7 ohms, the winding design is 10/48. Dumpload is two 1.8 ohma 2000w resistors connected in series, can they be used in a circuit according to your scheme. Because it's almost like a short circuit. Somewhere I read Cora's statement that such Chinese swg 120v generators block at 250v. It follows that if the aurora is damaged and is still powered from the mains, the turbine will rotate to a voltage of 250v. Whether the only way out is to manually disconnect. Contact missing inverter fault?

[Cor van Houtum]

Hello Robert

The voltage from the generator is depending on the RPM
this generator can easy go up to a voltage of 800 volts
if it is on the loose

If this happenes then the party is on , the inverter will blow

So it is very important to keep the generator within limits

depending on the wingspan there will be a horsepower coming from the blades
and now you want to use the generator to brake this power
Let's say in high winds the force on the blades equals 3 HP
The generator is only 2 kw
do you think that this can go on for a while ?
No the generator wil burn if you brake it on this HP for a longer time.

This is something the chinese seem not to understand or it is because of the money that they deliver always controllers with to little resistor power
or the relays are to small to handle this power.

at the same time they advertise a low wind turbine,
a low wind turbine is a small turbine generator with to big blades !!
What happeness when this comes in high wind ?
you cannot brake it anymore.

What is the bad thing of a SWG 2kw generator ?
The bearings are bad
The isolation will go bad after a year
then the inverter will go on RISO error and does not absorb any power
The blades will spin up and the generator reaches the high voltage that will kill the inverter and even throw the blades in the garden from the people next door.

So it is very important not to look at the inverter
this is not interesting yet !

First and first and first you must tame the windmill without use of the inverter.
the controller should do this.
It must be so that the windmill will not run away in every weather without it is connected to an inverter.

We found that the 2kw generator must be braked at maximum voltage of 230 volts DC output of the rectifier bridge

The braking should be done on the 3phase AC site
In high wind it is possible that the generator produces 4000 watt easy.
not long offcourse because it will burn.

To start with is the wiring in the tower !
this should be minimum 10mm2 on every leg
a thinner wire will act as a elastic on the braking system.

Then you can start calculating what the resistor should be that is used as a dumpload.
and the relays that make the short circuit to the resistors .
This is the first point of faillure

When you want to brake 4000 watts of power on a voltage of 230 volt
The Amps that occur will be NOT BE 17 amps

17 amps is the power when we generate 4000 watts

If you dump this power to a 3 ohm resistor
you get a complete other story

U=IxR so with 17 amps and 4000 watts the resistance of the turbine is
U/I = 13 ohm

When you in running mode short circuit this generator to a resistor from 3 ohms then the amps will be about 80 amps for
a short moment on every leg

It jumps back to a lower voltage and your controller senses this , and let go again
in the fly time of the relays the windmill spins up and up and up
So your controller should have a timer that brings the generator down for several seconds so it becomes in the accepted speed , and then it must let it go again.
It is not to say how many seconds it should hold the relays
this is to see in practice because the resistance of the complete system also depends on cables etc.

[Cor van Houtum]

Hello. Thank you for your response . I understand that the most important thing is to protect the devices against 530v voltage and destructive rotation. I am afraid that the problem of the winding breakdown is too aggressive consumption of power and I will use a full shutdown for 1 hour. I will use the device only in the winter, then there are less violent winds and the wind is more stable and has a higher speed. I will ask if I am to use a dump on the ac side, will they be enough for 3 1.5kw 230v heaters. And will the inverter start receiving power after such a 1-hour standstill before the turbine starts up and turns off again? I assume a starting voltage of 70v. greetings


Kind regards Robert

[Cor van Houtum]

When I say the dumpload should be on the AC site of the turbine
I mean the AC site coming from the turbine generator , the 3 wires AC

so never to dump after the rectifier
there you have DC and this is not the place to connect any dumpload

dumpload is not on the grid , but on the generator

A other thing to understand is that the chinese say in advertizing this is a 120 volt engine
this has nothing to do with the grid
these are the nomimal windings and the output of the generator

sometimes they say a 120/240 volt and now you think this is the grid amerika/europe
but also this is nonsense .

the used inverter makes this difference and not the windmill

[Rob Beckers]

To add to Cor's words of wisdom: You have to assume that the grid is most likely to fail during a wind storm (trees falling through power lines and such, unfortunately a frequent event where I live). That means your inverter is useless to keep a wind turbine under control. A safe setup means the turbine will not run away regardless of wind speed, grid AC, etc. Of course, at the same time you want to keep the alternator from burning up as well, which limits what you can do with a dump load. It's a fine line...

There's another wrinkle to this, that hasn't been mentioned yet. While a rotor producing, say, 5 HP cannot be kept under control by funnelling 3 HP into a dump load, rotors are actually highly non-linear. The trick for keeping a turbine under control with a dump load is to make sure there's enough load to slow down the blades so they aerodynamically stall, and the rotor stops producing large amounts of power. This means putting on the 'brakes' at a low-enough wind speed where this can still be done without burning up the alternator, and then keeping it stalled. The harder the wind blows into a stalled rotor, the higher the angle-of-attack of the wind vs. the blades, and the more it stalls.

The better designs do not rely on just a dump load or stalled rotor, but add backup in the way of furling, blade re-pitching, a mechanical (disk) brake etc.

Getting this right involves much voodoo & black magic (and lots of testing and destroying turbines and alternators)... :nuts:

-RoB-

[Cor van Houtum]

Thats how I know you
Right in the middle :D

[Robert Bilski]

Hello . This is how it works, the receiving resistance must be lower than the winding resistance, otherwise the turbine heats up. According to Cor calculation 13ohm is the ac side load. I understand that it is 3x 13ohm, delta connected.

[Cor van Houtum]

you only have circuit resistance

and one can not be lower or higher then the other

the resistance on your dumploads is and stay's about the same (temp not calculated)

The voltage however drops if you start to brake , but this does not happen instantly
because of the enertia of the machine it will take time to react
this creates a peak in power to the dumpload resistors and the electronics
(its like almost a short circuit)

to keep the resitors in good state you must have about tripple absorbsion power of these dumploads

so a 2kw machine will be dumped on 6kw resitors in practice
and offcourse with the right value in ohms

this is how it works

[Cor van Houtum]

please Rob HELP !!!!

[Robert Bilski]

Hello. I start with the bearings because there is longitudinal play. The winding looks like new, no earth faults. Thank you greetings

[Robert Bilski]

Hello. The first test was negative. Error on my side, the connection to the generator is terrible. I have the tail deflection cables and the measurement from the commutator is 3 ohms per phase. And what goes to the rectifier is 3 and 6 and 9 ohms. The balance of the blades was also bad. In the wind 3ms with no load 170vdc. It looks good. regards

[Robert Bilski]

Hello. I started it with small errors .1- the cable from the generator to the inverter only 6mm 2-commutator brushes had to get in so that the resistances on the windings were equal. Due to legal regulations, the mast is only 6 m high, but it is attached to the building which acts as a diffuser. Now I have to trim the trees that are obstructing my airflow. Using the Cora posts by creating the power curve, I set the maximum voltage value to 230vdc. I also set the value of turning off the turbine with a load of 3x2000w using a cheap Chinese relay Grv8-01 ad240 at 230 vdc. I noticed that when the wind turbine is working with a stable wind, everything is fine, but when the wind is not stable, it always turns in one direction. The wind weakens and the turbine performs the folding motion. Maybe it's a turbine thrust effect. I am only happy with the fact that I have not had the opportunity to test the devices in higher winds. Thank you again and happy holidays.

[Robert Bilski]

Hello. I confirm that the power of the wind is difficult to tame with 4kw chiles. It works very well, but for the next winter I don't think I will mount it again, because I only visit the house on weekends and I am not able to control it. In fact, this generator is very quiet, it can stand outside the window. I learned the principles of operation and such a simple model without the possibility of mechanical braking is dangerous. Another toy is the sofar hyd 3600. Regards

[Rob Beckers]

Robert, do you have any pictures of your turbine as it is mounted on the side of the house?

-RoB-

[Robert Bilski]

Hi . Currently, there is a generator without blades and tail. I only have one photo of my Siberian cat with a turbine in the background and this unfinished roof. It's fun and all you need to do is replace the bearings, balance it dynamically and it is very pleasant to sleep in the winter when the wind is blowing outside. Once again, thank you very much because thanks to such enthusiasts who are able to share their knowledge, you can build something useful. I increase the power of the panels to 6kwp. 3.3kwp ongrid rest onoffgrid .10kw agm batteries almost free. I put up the topic of a wind turbine whose location casts a shadow on the solar panels. The reason is a monoblock heat pump that works without glycol and in the current political situation, the solution was to buy Sofar solar hyd3600es.