basic 3 phase turbine won't run

[baffled]

Hello Panel,
We've been long time off grid people. We have a new turbine purchased a year ago. A 24 volt 2 KW  We were one of the first if not first purchasers of this new design and it has been problems for a year. It is a 3 phase turbine. The controller awaits repair and is a complicated affair since the turbine has no furling mechanism. It relies on the controller to slow itself down in high winds and when fully charged.

I am exploring simpler controller options. A simple diversion charger. Here is the problem. I have tried a test. I have 3 components. Turbine, 3 phase rectifier and 24 volt battery bank connected. The turbine starts easily in 4-5 mph wind and starts to produce  a couple amps at 10 mph. So far so good. But as wind speed increases, the turbine barely speeds up. In 20 + mph I might be making 4-5 amps. It self regulates and loads down and just won't turn with any speed.

I tried another experiment. I disconnected the 24 volt battery bank and connected a 12 volt car battery. It actually was a little worse. In strong winds, it turned a little slower and I could only get a couple amps regardless of wind speed.

I am aware of cut in voltage but am uncertain how to measure properly and whether it applies here to our problem.  Although the turbine is supposed to be a 24 volt configuration, I really have no idea what the actual turbine is wired for and how the electronic controller works with that voltage to make it run properly.

As it stands, we have a turbine and rectifier and cannot get it to fly with our batteries. Neither 12 volt or 24 volt battery size. It is the most basic system and I'm hoping someone has a clue. Thank you all in advance for any input you may have.

[bob g]

who made this thing?

got any pictures of it, or a link to the product?

how big is the blade set, diameter?

how many blades does it have?

lots of questions, a picture could probably answer.

bob g

[Flux]

At  a guess I would assume that the complicated controller is a form of mppt converter and without it you are just hitting hard stall. The fact that it was worse at 12v just confirms this.

I would imagine the alternator is deliberately made very efficient to get good results with the proper controller. If so you are unlikely to get anything like the original performance, It may better suit 48v or higher without the controller and even then you may have to deliberately introduce losses. If you manage to get it out of stall then without furling you will be in big trouble if you live in a windy area.

Flux

[baffled]

Hi Panel. Thanks for taking some time with this. The turbine is a wind Arrow 2 KW from True North Power. It has 3 blades. My understanding is it is manufactured in the US. I believe the head to be decent but am uncertain about the controller. It's a long story but the turbine did not work satisfactorily. Then the controller developed a problem. The company would not send out a new controller and sent me the parts to repair. The repair did not work so it is back at the factory. Meanwhile we sit and wait and wait. It's been quite the fiasco and I certainly regret our purchase.

I am of the belief that a higher voltage may get it to work. Like 48 volts. I don't have the batteries to try that as an experiment. Even if it worked our system and inverter are 24 volt and it would be quite costly to switch up to the higher voltage.

What is it about this 3 phase alternator that is different from any other alternator that it can't fly freely and needs some fancy controller? What is the controller doing to allow the turbine to run freely and produce power? Am I really stuck with relying on this companies controller with no other viable options. 

[Watt]

As Flux suggested, I believe the controller to also be a MPPT variety. 

Have you tried letting the turbine spin OC to see what sorta voltages you get?  If the voltages are under 250voc, you could put a controller such as a Classic from Midnite Solar on it and build a quick power curve just to see what kinda power it will make yet allow you to retain the 24v battery and inverter system. 

Three phase is a very common turbine electrical scheme.  The difference in requiring a complicated controller is probably nothing more than the MPPT logic suspected. 

Try adding some resistance in series on the dc side to see if your turbine rpm will go up. 

[tanner0441]

Hi
 
I looked at the manufacturers site. It doesn't tell you much about it, looking at the graphs it needs over 30 MPH winds to reach the rated output, but it also mentions 30 to 60 MPH, a swept area of 2.1mtrs seens small for a 1KW turbine, and I could not make up my mind if it is a synchronous generator. It mentions active motor to spin it up and look for winds.  It also seems to be the only product they make.

Brian

[bob g]

i too took a look at the website for the arrow 2kw machine
it appears they advertize 2kwatts at ~26mph windspeed and between
600-1000watts in 30-60mph winds?  not sure whats up with that.

it does look to me like the controller is anything but "simple" likely as Flux and others have concurred with "mppt" or somesuch in nature, which btw might be interesting to learn how they do it.

one side note they list is the blade pitch is adjustable? if so you might be able to get it up to something useful by adjusting the pitch to something a bit steeper than it is setup with now?  it might allow it to
spin up a bit faster and get something out of it.

failing that adding resistance to the DC side would get it to spin up as already stated, but that resistor has to be large enough to handle the full power of the generator?  shouldn't it?  if not what happens in a stiff wind and the resistor melts down?  a runaway?

if it was me, i would be on the phone with their engineering dept, talk to them about replacement parts, and get that thing to someone qualified to make the repairs needed... you might get lucky and talk to a sympathetic person that might even forward you a copy of the controllers schematic?  stranger things have happened and it sure can't hurt to try.  lean on them about being offgrid, poor as a church mouse, and needing the machine in operation to provide life support for a family member if you have to.

you paid for the thing, the least they should do is either fix it, "or" provide parts and a schematic so that you can get someone to fix it for you...

that schematic would be very interesting, and i would suspect there would be much interest on the forum in taking a look at it.

what i would not expect is any sort of "code" that they have developed to make the microprocessor work, that is asking way too much and the odds are very good it is proprietary and likely better that you will win a huge lottery before they agree to passing that out.

but it can't hurt to ask "after" you have the parts and "after" you get a schematic.

remember, be patient and persistent, and by all means do whatever you have to... to actually talk to someone in the engineering dept. not in the technical dept or certainly no one in sales. you have to get creative to get to them, but it can be done.

just to help take the sting out of things, i would gladly give you 20 bucks for a full copy of the schematic!  i suspect others might follow here as well, who knows you might (if successful in getting the schematic) recoup some of the money you are out.

fwiw, just something to think about.

bob g

[baffled]

Without going into a lengthy discourse.... we have been off grid since 1979. The manufacturer in the U.S. I believe is pretty much a one man show building this turbine. We have dealt directly with him as well as True North. No amount of pleading and emails and phone calls has swayed either company to promptly resolve the problem. I don't think they have a clue as to what it's like to be off grid and actually be so dependent on solar/wind for their power. They are connected to the grid and all is well with them. Meanwhile, we're firing up the generator frequently to keep our freezers going.

The controller died in December. I had a career in electronics so am capable of a fix. No schematic or instructions were sent with the parts so somehow manufacturer and I were not on the same page as to what they actually wanted me to replace.

No way I am aware of to adjust the blade pitch. There are several blade configurations. This is a fixed blade. I just received a response from the company. Doesn't make much sense to me. Basically, the rectifier output is too low (battery terminal voltage, 24 v nominal) and is loading the turbine. It is an AFC controller and somehow the 24 volt turbine via this controller operates at 40-60 volts , pulses the battery to charge and allows it to spin at proper RPM.

I let the turbine run briefly at open circuit and got to 70 VAC on one of the 3 phase windings. I have looked at the midnite controllers. It would be an expensive experiment if it still didn't allow this turbine to put out proper power. When I was troubleshooting the unit last Fall I was getting 50 VDC on the output of the rectifier with the controller hooked up so there's no doubt that the controller is somehow conditioning the voltage on the rectifier output much higher than if the rectifier output was tied directly to the batteries.

At some point this summer I am hoping to finally get a repaired controller back. In my frustration here I was hoping to at least utilize this gizmo to charge up our batteries. Since this doesn't seem to be a simple procedure, I don't want to do something to destroy the turbine and make the situation worse. We have about $7000 invested just in the turbine and controller. Far more if you add in generator fuel, shipping etc.

I may consider the resistor option. As it stands now, the rectifier output goes directly to the batteries. Is the suggestion to take the positive lead off and stick a resistor in series with that to the battery? What value of resistor?  I have two .75 ohm 1000 watt resistors. I have other power resistors but not nearly that big. Any suggestions on value.  It's a dicey experiment since if the resistor opens, the battery disconnects and the turbine is out of control. Maybe worth a quick try though just to see effect. Thanks folks.

[Watt]

One other thought would be, and this is if you have 70vac between two phases and not 70vac phase to star connection, three 2 to 1 step down transformers connecting one transformer per phase/phase connection.  That would bring your oc dc voltage to around 50v.  At the least it may allow you to nearly double your turbines rpm.  Any chance you have 480vac to 240vac/120vac step down transformers for industrial motor starter panels? The work pretty good for experimenting. 

You may find cut-in will be raised and lower wind speed performance may suffer a bit. 

[baffled]

Thanks Watt for the suggestion. I do not have the suggested transformers. It's an interesting thought. I'll price some out and keep it in mind. Have a good day!

[thingamajigger]

@Baffled
The wiring diagram is on page 25 of the pdf document that can be downloaded at the site link you provided. This is a basic 3 phase, rectified, buck controller with an overspeed stator shorting relay and I hope to hell they had the common sense to use caps across the overspeed relay contacts. If you have worked with electronics you could probably build one of these units in your sleep as there isn't a whole lot to them. Google wind power buck converter for more info.

Regards
Thing

[baffled]

Hi Thing...,
Good pick up on the document. Thanks for your feedback. Unfortunately, that document is for a 1KW unit and was drawn in 2008. This is a brand new turbine/controller on the market. We are one of the first to have ever bought one. I can tell you the controller is significantly different than pictured although the concept may be the same as far as operating principle. That relay is a safety thing and isn't for overspeed at least that I am aware of. The turbine never ran long enough for me to really get a good idea of performance. The relay is a good idea in that if for some reason the power is disconnected, the relay closes and effectively shorts the windings stopping the turbine. There are banks of capacitors in there also probably to act as a buffer so the turbine has something in case of battery disconnect or electronic failure.

The most interesting thing is that the old 2008 units were 48 volt wild AC . If that is still the case, maybe the suggestion from Flux is correct and it might have worked if we had a 48volt system. I will research a Buck controller but I suspect this controller is more complicated. For example, there are no user defined set points which I feel is a real problem. There is a programmable chip that has magic programming on it. PROM or EPROM  Whatever the factory ships with for set points on that chip is what you are stuck with. I have no idea what other parameters are programmed on to the chip. Forget equalization or modifying for your particular system. No tweaks possible.

Ideally, I just wanted to utilize the turbine without controller and charge our batteries until the repaired charger comes back. If it fails again, I'll have to consider other options like the midnite products.

[Flux]

I haven't looked at the web site but it does seem that they are trying to do what the Classic does but on the cheap. The Classic is basically a buck converter that lets the turbine volts match the prop output to keep the prop on the peak of its curve ( mppt).

With the Classic they got it right, it is efficient, can be programmed optimally and most important it seems to be idiot proof and this is where cheap copies will fail as you have found out.

If the rest of the turbine is well designed and built it may pay in the long run to use the Classic with it, the performance will be way above anything you will achieve with direct connection even if you transform the volts down to something more suitable.

As for protection in gales without furling, that will depend on the alternator being stiff enough to be braked to a standstill from any wind speed, I suspect the classic can be programmed to do that but I don't know. Still don't like the idea as any electrical failure in alternator or wiring will let it running flat out on no load.

Flux

[baffled]

Good advice and my thanks to the board for their input. I can see this is not the easy direct hookup I was hoping for until our controller gets fixed. I don't want to take any more of the panels time on this. Looks like I will have to continue the wait for our controller. If it fails, I will look at the classic as the next option. Thank you so much.

[thingamajigger]

@Baffled

I would imagine the 2Kw circuit is almost identical and there are only so many things which could change. Flux has it pretty much nailed however there are some details in the documents which give some insight into what they are doing.

From the manual----

If the wind is steady at approximately 10-12 km/hr (6-8 mph), the blades should begin to rotate.
Startup depends on how gusty or steady the wind is as well as local turbulence. If the wind is in
excess of approximately 12-15 km/hr (8-10 mph) the blades should quickly gain speed to the point
where the wind turbine is delivering power to the load. Power is being generated and sent to the
battery or the immersion heater when the lower BLUE LED labeled “PWM” is flickering or solid.

This means they buck/switch the DC from the rectifiers (PWM) which reduces the generator load so the rotor can spin faster to the point where it is most efficient or produces the most power. Basically we want the rotor blades to be operating at peak power(MPPT) which can be any RPM/frequency or generated voltage then we condition the power to efficiently charge the batteries at a lower voltage. The capacitors in the circuit before and after the buck converter section simply smooth the current which changes drastically as the switch cycles.

To stop the blades from turning, or prevent them from starting select the FLY/STOP switch down to
STOP. The blades can no longer “Fly” and should quickly come to a stop, although they may
continue to “rotate” very slowly in a moderate to high wind. In strong steady or gusty winds just
above 65-70km/hr (~ 45-50mph) the SOS may engage to prevent over speed and over production.

This is the part where they mention the overspeed/safety relay cutting in to brake the rotor and they use a time out to prevent the relay from rapidly cycling which would probably erode the contacts prematurely and may produce voltage spikes or transients that most electronics don't like. This is the weak point in my opinion which may have been upgraded to SCR's or an equivalent to add durability as well as smooth the sharp transition between the on and off state.

Even though the turbine rotation has been halted, either by operator action or by
SOS mode engaging, you should not attempt to restart the turbine if steady winds
or gusts are exceeding 70-80km/hr (45-50mph). If the blades are allowed to
accelerate rapidly beyond that speed the turbine's electromagnetic braking may
not be strong enough to overcome the aerodynamic lift created by the blades. This
is an unstable condition and can lead to structural failure.

Doh, I don't like this part and structural failure is never a good thing, this also means that if the contacts of that wonderful little relay ever fail to make contact which is almost guarateed in the long term if precautions are not taken then disaster is imminent.

It seems like a good enough machine however they may have a few bugs to work out with there electronics. I work with PLC's and automated systems on a daily basis because damn near everything is automated now a day's and can tell you most all the input sections I see are weak as well as the electrical/mechanical interface. I understand they are just trying to cut costs however in electronics there is a right way and a wrong way of doing things and if a person has a clue what their doing the right way is usually cheaper in the long run.

Regards
Thing