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Energy/Electricity Storage and Use/Grid Connection => Off-Grid, Batteries & Inverters => Topic started by: camillitech on March 31, 2016, 06:47:26 PM



Title: AC coupled direct heating thoughts
Post by: camillitech on March 31, 2016, 06:47:26 PM
Thanks to Heinz, CharlieB, Raasay Primary School and Bob the fire eater, over the last three years I've managed to acquire a complete grid tied Proven 6Kw turnip. Everything including 15m tower, carbon fiber blades, inverters (3kW Outback and 6kW Aurora) two controllers and a 950Ah forklift pack for less than 2kW of solar panels  :o I'll have to spend a couple of K on the turbine head and tower foundations right enough but even so it's still a lotta gear for the money.

Anyway, now comes the tricky bit, trying to integrate this into my 'off grid' system  ??? I can't really 'AC couple' any more kit into my present system without spending much more cash on either sophisticated dumps or another SI6.OH and upgrading the supply from my 'power station' to the house. So what I've come up with is a scheme to use all the kit I already have requiring me to only purchase one extra item, the 6kW diverter.

(http://i224.photobucket.com/albums/dd170/camillitech/P3310095_zpsuhk9uwg8.jpg)

The 'half baked' plan so far is to do something like the drawing. The 6Kw immerser is already in the 1500lt TS and I'll have a temperature controller in there that'll switch over to an air heater just before the thermostat on the immersion element opens. The export clamp sensor will be on 'AC out' of the 'Outback' and set at say 100w to keep the batteries topped up with a TriStar in diversion mode to keep the batteries safe. There will be a permanent connection to a nearby broadband mast I supply and a transfer switch so that I can use this system in the house should the Sunny Island fail.

I know it's rather complexicated but I have acquired all this kit over the years for next to nothing, all I need is the Immersun type device. As well as providing extra heat into my store and relieving pressure on the Sunny Island this will also give me a completely separate system and 100% redundancy.  

Any thoughts chaps?


Title: Re: AC coupled direct heating thoughts
Post by: rogeriko on March 31, 2016, 09:26:25 PM
There are several immersun type devices out there with 2 outputs i expect you could couple the outputs together to make 6 kilowatts


Title: Re: AC coupled direct heating thoughts
Post by: camillitech on March 31, 2016, 10:27:56 PM
There are several immersun type devices out there with 2 outputs i expect you could couple the outputs together to make 6 kilowatts

Aye Roger, I've found one that'll do the trick, just wondering if it'll all work in harmony, the whole thing hinges on that device not allowing any more than 3kW back into the Outback  sh*tfan:


Title: Re: AC coupled direct heating thoughts
Post by: billi on March 31, 2016, 10:33:54 PM
.... Hi Paul , me not understanding  all right now , but might be  other story  tomorrow  ...touch wood   banghead:  but  wout not be a transformer be a help ?  https://www.ecoinnovation.co.nz/p-420-30-kva-variable-ac-3-phase-transformer.aspx 


Title: Re: AC coupled direct heating thoughts
Post by: heatherhopper on March 31, 2016, 11:15:01 PM
Quote
rather complexicated
Like billi I'll be sleeping on it! Appreciate the reasoning and use of available resources though.
First thought would be that this is the time to go completely AC coupled - ready market out there for all that DC stuff you have which would largely fund the relatively modest extra bits you would need. I am biased though!


Title: Re: AC coupled direct heating thoughts
Post by: camillitech on April 01, 2016, 06:47:12 AM
Morning chaps,

yes Billi, I'd never thought of a transformer, will give it some thought but I don't think it'll help in this instance. I would still need some way of loading the turbine proportionally to stop it stalling.

Hi HH, to go down the total 'AC Coupled' route I'd need another SI6.OH at least, perhaps an SI8.OH or even two 8s my wind capability alone is a PV equivalent (as far as SMA are concerned) of 18kW then I have 1.6kW of hydro and currently 5kW of PV. Methinks max for the SI6 is 11kW of installed capacity when using FSPC. Then I have the problem of having to increase the cabling from my power station to the house. The 6kW turnip would be wired directly to the 'bunker' (on back of house) where the TS is. Also, I already have everything else and the 'Power One' doesn't 'frequency shift' as far as I know.

Cheers, Paul


Title: Re: AC coupled direct heating thoughts
Post by: heatherhopper on April 01, 2016, 11:53:42 AM
Sorry Paul - my AC coupling suggestion was more tongue in cheek than serious although you are most of the way there anyway in reality.
In my simplistic view if you have reliable FSPC driven load control on the AC side the SI only ever "sees" the portion of AC input required for battery charging (which itself is limited) and FSPC continues to operate normally despite SMA "limits". Can all go wrong if that load control fails I suppose. Certainly adding another SI would give you the required configuration but would be costly and I see this is not desirable.
Don't quite understand where you get 18kW of wind capacity?
If you can't get an Immersun type device to work satisfactorily could you not simply use an SSR to proportionally control diversion to the TS - different control options available and cost possibly less. You already have this kind of set up on the DC side?


Title: Re: AC coupled direct heating thoughts
Post by: camillitech on April 01, 2016, 12:43:02 PM
Sorry Paul - my AC coupling suggestion was more tongue in cheek than serious although you are most of the way there anyway in reality.
In my simplistic view if you have reliable FSPC driven load control on the AC side the SI only ever "sees" the portion of AC input required for battery charging (which itself is limited) and FSPC continues to operate normally despite SMA "limits". Can all go wrong if that load control fails I suppose. Certainly adding another SI would give you the required configuration but would be costly and I see this is not desirable.
Don't quite understand where you get 18kW of wind capacity?
If you can't get an Immersun type device to work satisfactorily could you not simply use an SSR to proportionally control diversion to the TS - different control options available and cost possibly less. You already have this kind of set up on the DC side?

Aye HH,

the 18kW comes from the 3kW and 6kW total capacity doubled as per SMA recommendation for wind. I did seriously think about relying totally on my AC dumps to ease pressure on the SI and have not ruled it out yet. I need to speak to Hugh about that, I had convinced myself that I needed to upgrade the 50m long cable from the 'power station' to the 'bunker' where the TS is to go down that route. However, if the 6kW inverter is already in the 'bunker' I guess I don't in reality, as any power produced by that would be going straight into the store.
I had thought I'd 'future proofed' the cabling issue by running everything in a 100mm duct but that's well full now!! A bit of forethought and I'd have laid two or even three, one for AC, one for DC and one for control/Ethernet but 'you live and learn' hey.

Cheers, Paul


Title: Re: AC coupled direct heating thoughts
Post by: Mostie on April 01, 2016, 03:40:39 PM
Paul, what happens if the 3kw inverter goes "offline"  assuming it will take the GTI and the big diverter with it  help: sh*tfan:    :crossed


Title: Re: AC coupled direct heating thoughts
Post by: camillitech on April 01, 2016, 03:58:38 PM
Paul, what happens if the 3kw inverter goes "offline"  assuming it will take the GTI and the big diverter with it  help: sh*tfan:    :crossed

Hi Mostie,

firstly the turnip voltage builds up to around 440VDC when the 'over voltage' protection kicks in (big resistors) but these are more a 'safety net' for the inverter. The Proven turbines are quite happy running off load, which is what would happen if the protection and inverter failed. My neighbours Proven ran through several storms and a hurricane unloaded and took no harm, in fact, on battery charging models that's their 'third line of defence' if both dump loads and 'trickle charge' circuits fail. The unloaded turbine simply 'cones', speeds up slightly and makes more noise.

Cheers, Paul


Title: Re: AC coupled direct heating thoughts
Post by: Fionn on April 01, 2016, 04:24:40 PM
I realise you're making best use of kit you have already but the whole affair seems hugely complex for something that essentially just turning mechanical energy into heat.
Surely a controller exists that will PWM the DC output of the turbine directly into a resistive load based on either the DC voltage or an RPM signal from the turbine?


Title: Re: AC coupled direct heating thoughts
Post by: camillitech on April 01, 2016, 05:31:27 PM
I realise you're making best use of kit you have already but the whole affair seems hugely complex for something that essentially just turning mechanical energy into heat.
Surely a controller exists that will PWM the DC output of the turbine directly into a resistive load based on either the DC voltage or an RPM signal from the turbine?

I'm sure you're right Fionn but the Outback and battery bank are already installed in the 'bunker'. I got the battery bank given, the Outback 'for buttons' and fitted it some months ago as a 'back up'. Same with all the other kit, TriStar was free, the Aurora and wind interface came with a load of other kit for less than the price of a festival ticket and I already have all the cabling and switch gear. It's no more complex than the rest of my kit and it does give me complete redundancy for the price of a solar diverter, if of course it works that is  ;D Sure, if I was starting from scratch I'd be thinking along the lines you suggest, I can even lay my hands on a Proven 'Direct heating controller' which does exactly what you recommend. However, by adding just a couple of switches I can disable my 'AC coupled' solar in the depths of winter and feed the turbine output into the SI's grid thus running other electrical loads and charging my batteries. Solar isn't worth a feck here in the winter, 5kW of solar PV gave us just 148kWh in Dec/Jan and 60 tubes nothing! my 2.5/3.2kW Proven on the other hand put out 1718kWh. Come the summer it's the other way around right enough Jun/July 863kWh PV and 360kWh wind. The thing is we're TOTALLY electric bar the cooker and I'm aiming for ZERO generator usage and an electric car. So far we've run the generator 117 hours in 13 months but by next year I want that to be 0  ;D

Cheers Paul


Title: Re: AC coupled direct heating thoughts
Post by: Fionn on April 01, 2016, 05:36:21 PM
That's a fair point Paul, however if I were in your suggestion I'd probably flog the stuff you don't need and use the proven controller. The profit could be put away for when your main system needs new batteries or whatever. I can't help but think that the battery bank you have on this system will be pretty under utilised.
All that being said, you'll have a great system when it's done and super redundancy as you say, that's obviously of more value to you.
I'd just be nervous of the time it would take to maintain/monitor and the large number of possible failure points.


Title: Re: AC coupled direct heating thoughts
Post by: camillitech on April 01, 2016, 06:11:26 PM
Hi Fionn,

living in the sticks I rarely sell anything, bit of a siege mentality  ::) probably end up buying the controller anyway  banghead: what you say makes perfect sense and I'd probably advise anyone else to do the same, but I do love tinkering about with all those shiny red, yellow and silver boxes  ::) Truth is I really must get out more  wackoold Do you think it'll work though  ???

Cheers, Paul


Title: Re: AC coupled direct heating thoughts
Post by: guydewdney on April 01, 2016, 06:55:08 PM
if the 6kw immersun device cant let any more than 3kw 'past' it then you need the secondary load (after the first immersion is 'satisfied') to be 'infinate' without a thermal trip, eg a sauna heater like mine.


Title: Re: AC coupled direct heating thoughts
Post by: Fionn on April 01, 2016, 09:12:08 PM
I'm sure it will work fine Paul. I'd probably add another voltage relay in parallel with the feed to the TS in case the diverter failed.
Guy makes a good point on the final dump also.

I'm guilty of being a bit of a hoarder myself but am in the midst of a huge clearout at the moment. I have to say it's quite liberating if not all that financially rewarding.
I actually have a 60Hz Aurora 3600 Wind inverter that is crying out for this type of an application since it's not useful for much else this side of the water  ;D


Title: Re: AC coupled direct heating thoughts
Post by: camillitech on April 01, 2016, 09:23:49 PM
if the 6kw immersun device cant let any more than 3kw 'past' it then you need the secondary load (after the first immersion is 'satisfied') to be 'infinate' without a thermal trip, eg a sauna heater like mine.

Hi Guy,

the Immersun type device will pass the full 6kW to the element but will only allow 50W to 350W to backfeed to the batteries via the inverter. That's adjustable and I was thinking of playing about with that, perhaps 100W. I was thinking that would keep my fork lift cells nicely floating and in good health ready for any unexpected incidents. The TriStar will take care of the EQing and I'd always have a fully charged bank to fall back on, or even use it to top up my main one every now and then. Funnily enough I recently recalled you mentioning sauna elements and I've bookmarked a few places selling them, though to be honest they just looked like regular cooker elements to me. Pretty sure they'll be more durable right enough but it did get me thinking about salvaging old cookers.

I appreciate it's a bit of a 'sledge hammer and nut' project but I do have all the stuff required here at home now, apart from the 6kW diverter. It goes against much of what I've said in the past about double battery banks but it would also give complete redundancy and the flexibility to bring more power to my main system during the winter when the solar does feck all. The simple direct heating method has much merit but I'd not be able to use the energy for anything other than heat and using an inverter programed with the turnips power curve will produce more energy than just driving a load via PWM.

Cheers, Paul


Title: Re: AC coupled direct heating thoughts
Post by: Mostie on April 01, 2016, 09:39:54 PM
6kw of big resistors  :P surely we must have a pic


Title: Re: AC coupled direct heating thoughts
Post by: camillitech on April 01, 2016, 10:18:55 PM
6kw of big resistors  :P surely we must have a pic

Well Mostie,

(https://lifeattheendoftheroad.files.wordpress.com/2015/02/080215-009_thumb.jpg?w=362&h=273)

here's 5.4kW warming up nicely

(https://lifeattheendoftheroad.files.wordpress.com/2015/02/200215-001_thumb.jpg?w=716&h=538)

half of the other 5.4kW in the 'power station'. Now with the AC ones taking priority they rarely get so hot.

This is one of the 1500W ones, each TriStar has one of these and a smaller one connected to it.



Title: Re: AC coupled direct heating thoughts
Post by: camillitech on April 01, 2016, 10:38:15 PM
I'm sure it will work fine Paul. I'd probably add another voltage relay in parallel with the feed to the TS in case the diverter failed.
Guy makes a good point on the final dump also.

I'm guilty of being a bit of a hoarder myself but am in the midst of a huge clearout at the moment. I have to say it's quite liberating if not all that financially rewarding.
I actually have a 60Hz Aurora 3600 Wind inverter that is crying out for this type of an application since it's not useful for much else this side of the water  ;D


Aye Fionn, that's exactly what I'd planned, an air heater operated by a relay that works if the immersion goes OC or the stat opens, and yes, the final dump is a good idea.

Shame about the 60Hz setting on the Aurora, you cannot alter that even with the computer generated password, apparently the frequency is embedded in the software,but I'm sure you know that.

I did have a mega clear out when we moved out of the old house, and yes, it certainly was 'liberating' but I just seem to keep acquiring things  :crossed

 


Title: Re: AC coupled direct heating thoughts
Post by: Mostie on April 02, 2016, 02:24:33 PM
thanks Paul, I'm never comfortable with those things next to wood  whistle