ZA Grid-connected Sytems

[dubbleUJay]

We've had some good news in South Africa recently, but first a little history just to put you into prospective: (Obviously this is my own opinion! )

After our ONLY national power utility company Eskom, made some crucial mistakes by not upgrading our grid for the past 14 years as they were told to do so when they "privatized", we now have legislation allowing private individuals to install grid-tied systems.
I remember a few years back before the S hit the fan, we had big headings in the papers about how much annual turnover they were making!
A few years later and we had national grid failures, power cuts, substations blowing up for lack of maintenance and upgrade exec.
As the "Gravy-train" came to a halt because of a lack in power, the fat-cats looked out the window and it was to late!
They now have competition which should have happened a long time ago! 

Anyway, enough of that, in a few days time someone is giving me the opportunity to take a tour of a wind turbine manufacturer plant right here in my home town.
These guys must be quite big as they have the backing of Eveready, the battery guys!

These are PM generators, but what intrigued me was that some of their products grid-tie without using any batteries! I never looked at grid-tied systems before as we couldn't use them so maybe this isn't a new thing?
What they do is generating 220Vdc (we use 220Vac in ZA) from the PM alternator, put it through a voltage limiter and then to a grid-tied inverter to convert to AC and sync to grid.
Are this a common practice in other part of the world like US & Canada? I believe that they are exporting to the US as well.
Here's a link to their site:
http://www.kestrelwind.co.za/
There are some diagrams on the site as well.

Any questions anyone want me to ask them, let me know, I'll be going there on Friday.
dubbleUJay

[mike90045]

Ask about :

monthly greasing for the bearings in the weather

If there will be a positive stop brake (Like a motorcycle disc brake)
Electronic brakes only work as long as the circuit card works. And they only get stressed in high winds !

Tower options - jib, cable-winch, hydraulic, tilt-up   (gotta get in there 2x a year at least to grease and clean)

Who controls the intergerty of the casting and welding.   Some awful ones are coming out of China

Are the electronics package UL or CA certified?

[dubbleUJay]

Thanks Mike, I can tell you the following as I've been to a site when they took one down:
No mechanical brake, only electronic that I saw.
This tower was free standing single "pipe" tilt-up. It pivoted more or less in the middle and was let down by a 12Vdc automotive winch they attach to the structure at the bottom. It was quite easy to come down, even when the wind was strong that day.
The blade hub design has a spring-loaded mechanical pitch control that regulates the max. RPM at 700.
I think the grid-tied inverters are imported from US, but the voltage limiter is made locally.
They use Windy Boy: http://www.sma-america.com/en_US/products/wind-power-inverters/windy-boy-3000us.html
Given the companies involved with this product (Eveready for 1) I presume the quality should be high as they wont associate there name with it if it wasn't.
The tower were hot-dip galvanized and all fasteners stainless.

This pic isn't the site I've been to, just found it on the web, but give you an idea of the tower construction.


I suppose they wont let me take pictures in the plant, but I'll ask anyway!

[mobile_bob]

i am guessing but it appears the rotor is over 12' diameter?

if so 700rpm is way too fast, none but those under about 6 ft will run and survive at 700rpm
the tip speeds become supersonic and rapid errosion of the tips result, and in some cases
all sorts of other dramatic failures related to vibrations/oscillation/resonance happen as you go
through the sonic barrier.

gotta watch out for the wind power claims, there are so few standards and no governing body to keep
things on the level, it really becomes a situation where "the first liar doesn't stand a chance"

not saying this about the example company, but keep a skeptical mind and a locked zipper on your wallet
till you get some serious questions answered.

bob g

[dubbleUJay]

BobG, thanks for the input.
The one he claimed can run at that speed were a smaller 1kW unit with a 3m (9'8" ?), but still sounds a bit fast now that I think of it that way! I might have misinterpret what he said though.

The pitch control on the blades are pre-adjustable to come in at various top speeds as I understand it.

I try and ask the right questions tomorrow

[dubbleUJay]

OK guys, I've been to the Kestrel factory and had some time to think about what I saw. They work in association with the battery manufacturer, Eveready, on this product.
As a matter of fact, the production line is inside the Eveready plant.
Also, I'm not associated with anything of them for those that wondered about that.
I've got no way of comparing the turbines with others as I haven't looked at any this close before.

That said, their turbines should be very competitive compared with others, because I think like this:
Eveready is a very well known brand in ZA and wont associate themselves with inferior equipment and they wont export to the US&UK if they didn't think its viable and they have a good product.
I can say this as I know how the guys over-here think and they are generally very proud of there work, a lot of us have some "German bloodlines"

OK, they manufacture the PM generators and the Voltage Limiter locally, the grid tied inverter they use/recommend is a SunnyBoy from the US. Maybe the SunnyBoy might put some prospective on the quality they have/want

The PM-gen is of Axial Flux design with metal core/plates in the coils. They have 12,24,48Vdc units, but also 110&220Vdc units. Most are wired "3-phase" to rectifiers ie, 3x rectifiers per generator. These are multi-pole, multi-phase units, ie, there are 120-pole 12-phase units available!
The quality of the design looks very good that I could see to my ability. No ugly welding, bearings all around, sturdy construction.

The aerofoil blades are also manufactured right here and so is the hub. They have an unique patented design for the pitch control which looks very good to me if that counts for anything.  

I'm still waiting to receive the costs of the units, which would be part of the deciding factor for me, should I get one.

[BruceM]

Gee, if Kestrel could just boost that 110 to 120V, I'd get interested.  Looks nice, that same mounting system is similar to what our local wind generator maker recommends. Easy to bring her down for a big wind storm, easy to service.  The axial flux PM head sounds sweet.

The Kestrel is way upscale compared to Mikeswindmillshop's truck alternator based design.   The upside of the Mallard is that it's cheap, and has a great track record locally for reliability, despite our nasty winds and weather.  The older stock blades were pretty noisy, nothing you'd want near the house. Other aftermarket blades are available, and it seems they've made some blade improvements.  

http://www.mikeswindmillshop.com/wgenerators.html

[dubbleUJay]

Bruce, I use 110Vdc loosely, we still think all of US use 110Vac, the UK 220Vac, but they have more towards 240Vac. We have anything between 210 & 250Vac I've seen in some places!

It should just be a matter of adjusting their "Voltage Limiter" a bit and I'm sure they would've made provision for such a small deviation, to get 120Vdc out of it.
The Voltage Limiter cuts in when the wind-gen starts producing whatever voltage you set it at and limits it when it goes above that voltage. Obviously with tolerances either way.
That gets fed to a grid-tied inverter. With your knowledge Bruce, you can make one yourself, for personal use that is!
Doing it this way, they're using the grid as a battery. Its obviously a $$$ saving thing with the batteries, but one wouldn't have backup power this way. This is the most basic system and you can add batteries later, or that seems to be their sales angle!
Hell, I'm starting to sound like one of their salesman!
On the Kestrel site there's a lot of PDF's for downloading. I only got them recently and haven't gone through them all yet.
There is a click-able map on their homepage, http://www.kestrelwind.co.za/ that I can see have 3or4 distributors in the US.
Maybe you guys know some of them, I've got no idea.
Here is one of them: http://www.dcpower-systems.com/group_detail.aspx?gid=27
I think they'll speak the American "lingo" to you guys and would probably give you a better answer on quality in their eyes, if you know what I'm getting at.

O-yes, almost forgot. Some of the models already out there are quite old and a lot has been done in the meantime to the new ones, making them better and more reliable I suppose. I believe there are a new shipment on its way to the US. (Overheard one of the guys speaking about it)
You also have various options for towers, 3-legged free standing, single with guide-ropes or the one in the picture above. All galvanized, or the ones here by us anyway, I don't know if they export the towers as well.
For myself, I'll also chose the one in the picture, all they do is connect a automotive 12v winch to the tower at the bottom, there is a mounting place for it at the base of the tower right on the frame, and you let it down or up, quite easy when I saw them doing it.

dubbleUJay

[mobile_bob]

what kind of wind resource do you have down there?

after looking a bit more into the product in question, i am pleased to see that they
rate it at a reasonable windspeed, albeit quite stiff, but at least not a hurricane wind.

the 1kwatt unit makes its rated power at 11m/s or about 25mph (if i converted properly)

at 12mph it will be doing good to make 1/8 that amount of power or 125watts, rather than the 250watts they
claim, but until i see otherwise i will give them the benefit of the doubt on this one.

in any event it is unlikely that the machine will make much of a return on investment in under 5.5 m/s or 12 mph winds
in my opinion, things fall off very quickly under those windspeeds.

for those with good winds, at least a couple days per week, it looks like a good machine.

much better looking blade profile than what is typical in this class of machine in my opinion.

just wish they published more details on the inner workings of the alternator, things like magnet grade, number of poles
dimensions would be nice.

are you thinking of getting one?

bob g

[dubbleUJay]

Bob, Port Elizabeth, ZA is known as the "Windy City" around here, so we get quite a bit of wind. I've stayed in other coastal cities as well and it doesn't seem that much different, although we had a record wind the other day which was recorded at 160km/h at times, the highest in 30 years the papers said, IIRC. That is out of the ordinary though.

The factory has about 10 various generators up on site and I saw an anemometer right in the middle of them. I think they took their reading claims from that, although they also had a wind-tunnel on site, but that's for blade testing.
So those figures should be real-world figures if one take the conditions around Port Elizabeth into account.
When I visit the site, the actual "know-it-all" guy we were suppose to see wasn't available so we had to make do with one of the other people.
There was some questions he couldn't answer, but he said I should direct it in an email to the "main penguin" (That rimes much better in my own language "Main Pikkewyn")

I also wanted more info on the dimensions and such, but its one of those "Top Secret" facilities by the looks of it, no cameras & stuff!
I'll see if I can get some answers from the guy in charge when I email him.

I was asked by some guys to asses their product for a venture they are busy with, but if I like what I see/hear and I can afford it, I will get one.
I already have a tower in place, but still need an "proper" inverter & wind-gen, one day!

dubbleUJay

[Apogee]

Interesting.

Was just reading about the e400, 3kw unit.

120 pole, 12 ph polyphase motor
3 bearings
sealed to IP55 standards
500 rpm
full output at 11m/s
cut-in 2.8 m/s
4m diameter
sound at rated output <30db

Looks nice!

I want one...

And, there is a local dealer in Bellevue, WA!

Steve

[BruceM]

The Kestrel is the first wind generator I've seen with an output near the 120VDC (nominal battery bank voltage) I need.  I expected to have to do something custom.  Thanks for your investigation and reporting, WJ!

The sound rating seems quite low on that big unit! 

[dubbleUJay]

I stand corrected Steve, the ones I saw was 3-phase, probably a batch of lower voltage ones. You're quite correct that there are multi-pole units.
I was told by them that they cut in at just over 2m/s and then Bob said something previously about 5m/s which I cannot comment on, so I kept quite until I have more figures.

I specifically ask the bloke we saw about the sound/noise. He said they went through various design modifications and came up with the current solution which they are happy with.

I'm going to try and get the main guy to answer some of the questions here on the forum. I can only contact him on Monday and I'm not even sure if he would or could give comments.

I'll try my best, I'm sure it would be in his best interest anyway.

Modified:
BTW, I think before/if someone considers getting one, we might try and find out if its the latest models with the latest modifications on it. Apparently there have been some good improvements done on them the last few months and I don't think you guys would like to get one that's outdated!
Just a thought,
dubbleUJay

[BruceM]

Most off grid homeowners here in the White Mtns. of Arizona have found adding wind to the power mix very helpful for winters.  (We have excess PV power in summer, typically.)  Our cloudy winter days are usually accompanied with storm systems moving through, with fairly strong winds, all day and night.  We almost never have overcast/clouds without wind.

Instead of a bunch of generator time on cloudy days, the wind generator assisted off-griders end up with a full battery bank.  Even at modest power output, charging continuously all day and night is a beautiful thing.

[dubbleUJay]

I must warn you guys though, I've still got no idea of what these things are going to cost, they gave me a bit of a runaround when I dropped the question, but I can assure you they wont be in the region of  "China" prices!
The ZAR/Dollar (+/- 8to1) exchange rate might make them affordable in the US.