New(ish) CHP in Scotland, botching and learning!

[michiel]

Dick,

Any leak off is soaked up by one sheet of (unused!) loo paper I fold up and put under leak off pipe every morning before starting engine.

Would a longer pipe not be more prone to blockage, as leaked of WVO will cool down and thicken up???
The short leak off now stays hot as is close to engine block + radiated heat from head.

[jotec]

That was exactly my thought but DS said differently. I have a tube that runs down to a container. The only thing I can think is that, perhaps, the veg as it cools picks up dust that eventually clogs the hole. If a pipe is attached then the dust can not get to the hole?

[eabadger]

Looks very good, did you ever sort the volts issue? How is the gen head excited? I don’t use a lister, but a pre lister enfield, had similar issue as old excitation units are a bit crude.
With new unit I now get 220v at 50hz and can load up to 27amps, see about 2hz movement when load drops in and out.
I have a small laser rpm meter to confirm engine is at 1500rpm, set this up and now all seems good.

Good luck with your progress,

[Cornish Dragon]

Well done Michiel....
Not a field I know much about but I have found it
very informative....
Anything these  days to get away from the energy
companies seems  good to me.....
CU
CD

[SimonHobson]

On the volts issue, output volts = k x number of turns in winding x field strength x speed, where k is a constant that takes care of all the various units and the design of the machine. Basically, since k is fixed, and the number of turns is fixed, you can only vary speed (keep everything else equal, and voltage is proportional to speed) or magnetic field strength (keep everything else the same, and voltage is proportional to field strength).

eabadger has already asked how the genny is exited/controlled. Depending on this, it may be a case of a simple adjustment, or there may be nothing you can do. But if you run the house on 208V, the light bulbs will last a long long time Stuff with switch mode supplies won't be bothered, but motor driven stuff (fridge, freezer and so on) won't be happy.

[michiel]

Hi,

I have not really spent anymore time on the V issue.
At the moment, the genny is connected to an immersion in the 1000lt buffertank. So the V is not a big issue.
I am however looking at connecting to an Aurora GTI. The Aurora will work on 200V input, I believe.
So even then, it SHOULD not be to big an issue.

It is a ST5 genny. Before switching engine off, the breaker is flicked, to disconnect the load.
Only once in the last year have I had to manually exite it, after engine stopped unexpectedly.

[SimonHobson]

Is your genny one of these (or similar) :
http://lerch.no-ip.com/ChangFa_Gen/Generator.pdf

Some more info here :
http://www.utterpower.com/voltage-excitation/
and here :
http://www.utterpower.com/Trouble.htm

While I was looking around, I also came across this page. Sounds similar to your problem - output voltage a bit low. Assuming the excitation winding, rectifier, brushgear, and rotor windings are all OK - then two suggestions are : to fit a DC smoothing capacitor after the rectifier, or supply the rotor from a separate power supply.


Some designs of generator (like the small petrol driven job I have for emergencies) have the rectifier on the rotor and no slip rings - and I forget how they work.

[michiel]

Hi all,

Sorry, been a while since checked this thread.

Just a quick update.

Have nearly finished purpose built engine shed, away from the house now, where both CS's will be installed, together with the WVO processing stuff.
Mrs.Z was worried about fire hazard, smell and noise in attached garage.
For once, she was probably right here!

Now I am completely redesigning setup, I want to look at grid connecting one of the CS's.

(I realise I have touched on some of these subjects in other threads, but this puts all together)

The one I want to use is on a 1ph ST5, 5kW altenator.
The CS will generate 3kW, but I find it runs efficient and happy at 2.2/2.5 kW.
I realise a 3ph altenator would have been better, but I believe a 1ph one, rectified and smoothed will work with the correct GTI.
(I have G59 protection)

1. Rectifying and smoothing.
          There are 'boxes' available for this of the shelf, such as the Aurora Wind Interfase, which cost about £350 and does more then I need.
          Would a suitable bridge rectifier, capaciter and AC / DC isolators in a box not do the job?
          If so, could anyone recommend which parts to use.
2. GTI
         I need a GTI that would work with a DC input of about 190V min. This would let me run the CS at a relaxed speed.
         The Aurora 3.6 would accept this. How difficult is it though to limit the Aurora to 2.2/2.5kW?
         Or is there another GTI out there at these outputs and input limitations?
        
I am not considering FIT's here, so ideally I would pick up something 2nd hand. Have seen a SMA WB 3000 on bay for £500. Also some Chinese stuff for £250.
So anyone upgrading with spare inverters, please let me know.

As I am now redesigning the setup, I am seriously considering doing away with the EGHE. Although it is very efficient, I have to clean it out (de-coke) every 50hrs. A job which takes about an hour, every week. The holes are just too small, and block too easily.
As suggested earlier, I might try installing it before the expansion tank first, where temps will be higher. The flow will be pulsating with the engine stokes though, which I thought was a dis advantage. (hence placing it after expansion tank)
An alternative would be to leave exhaust flow undisturbed, and run HW pipe along exhaust a few times. Less effective, I know, but a lot less hassle with de-coking and back pressure.

Am away right now, but on return will post some more picks.

Michiel  

[SimonHobson]

I'd have thought a rectifier followed by an inverter would be quite wasteful and expensive. I'd have thought directly connecting an AC machine would be better - but obviously you then have to sync it up before connecting and control the voltage & throttle to regulate export.

I suspect that with a rectifier & capacitor bank, you'd need to derate your genny somewhat due to the very poor load waveform you get with that type of load. The inverter should cope as long as you have enough smoothing caps - but more smoothing caps worsens the load waveform on the genny.

[michiel]

Simon,
ss
I want to grid connect this generator, as the second one feeds direct into an immersion already.

If I can cover my base load and let the "EMMA" unit divert the surplus, this seems the most economical use.
(NO FIT's involved here, so no need to lecture on morals!! )

I would use a 3ph rectifier, which I believe would work the same, using my 1ph generator.
If I have to upgrade to a 3ph altenator, I then wouldnt have to change the rectifier.
I assume the rectifier would be matched to appropiate V and A's.
What about the Capaiter(s)?. What rating and how many?

[Other-Power]

1. Rectifying and smoothing.
          There are 'boxes' available for this of the shelf, such as the Aurora Wind Interfase, which cost about £350 and does more then I need.
          Would a suitable bridge rectifier, capaciter and AC / DC isolators in a box not do the job?
          If so, could anyone recommend which parts to use.
2. GTI
         I need a GTI that would work with a DC input of about 190V min. This would let me run the CS at a relaxed speed.
         The Aurora 3.6 would accept this. How difficult is it though to limit the Aurora to 2.2/2.5kW?
         Or is there another GTI out there at these outputs and input limitations?
        

Aurora and SMA both good units and all the non HF or TL SMA inverters can be programmed for constant power points, ie 300 volts @ 3kW.

The Aurora wind turbine model can be programmed with a power curve, simple, all 16 points get set to the same point or allow for some ramping of the power.

Auroa units do not come up very often, and wind units very rarly, kind of rules them out.

SMA units come up a lot now, you want the older transformer based units idealy, you will need a service cable, Sunny and some of the basic log in settings.  The newer HF and TL units can be re programmed but you will need a grid gaurd code from SMA from memory, the connection for this is via Sunny Explorer and a usb bluetooth dongle.

As far as the rectification goes, a three phase rectifier from ebay for £30 will do as the SMA units can take a 10% riple with no worries.

Only thing is to make sure you do not over voltage the units.

Cheers

Jon

[SimonHobson]

I want to grid connect this generator, as the second one feeds direct into an immersion already.

I got that. By far the simplest and most efficient method of attachment is direct - as long as the voltage and frequency are correct. You haven't mentioned voltage or frequency, but as you'd mentioned running a (I assume) standard immersion heater, then I'm guessing they are 50Hz and 240V or thereabouts).

On startup you'll need to sync the genny before connecting it, the open circuit voltage will need to be enough to make it export, and after that I believe it should be just a matter of setting the throttle for the power you want to send. Syncing can be done manually, or there are automatic units that will sync up the genny and close a contactor at the right time. I believe there are also modules that will regulate throttle and field automatically as well. Potentially the equipment requirements could be a little as a light bulb (or voltmeter) and a breaker - but it's getting well away from the little I can remember from university days.

If I can cover my base load and let the "EMMA" unit divert the surplus, this seems the most economical use.
(NO FIT's involved here, so no need to lecture on morals!! )

Is it cost effective to export from the genny ? I was under the impression that a diesel genny is far from the cheapest option for lecky supply, so I'd have assumed that running a diesel genny to export would be pointless.

No lecture on FIT morals - hard to blame someone for taking money that's being handed out. Different attitude to the system iteself, but that's a different discussion.

I would use a 3ph rectifier, which I believe would work the same, using my 1ph generator.
If I have to upgrade to a 3ph altenator, I then wouldnt have to change the rectifier.
I assume the rectifier would be matched to appropiate V and A's.
What about the Capaiter(s)?. What rating and how many?

Capacitors - depends on what the inverter needs, smoothness wise. You'd need to speak with the manufacturer, since the inverters are designed for a different source, the information needed won't be in any spec sheets.

[michiel]

Simon,

I am not keen on connecting direct. Sure, I believe it can be done, but would not feel too happy about it, and wouldnt like to leave it unattended for hours on end. It will go wrong one day!
Definately want to go the GTI route.
Sorry, wasnt too clear about my 'Emma's'. They divert any 'over production' into a large 3ph 9kW immersion. Only when over-producing more then 3kW/ph, or 1000lt tank up to 80C will it export.


Jon,

Would 1ph, rectified and smoothed properly come within the 10% ripple tolerance for SMA?
Also, running the Lister CS at its most economical, output V is approx. 200V. Does the SMA not need 224V min. input? Or is this programmable?
As you say, quite a few SMA 2500's turning up now.

Michiel

[michiel]

So,

Needing a bit of help here.
First of all, has anyone got any 2nd hand SMA's 2500 for sale for reasonable money???

Also, regarding rectifying and smoothing my 1ph generator.
(Still want to try this first, before opting for replacement 3ph one)
Would I be able to come within the 10% ripple max. for SMA??
Sourcing rectifier should be easy enough, say 600V ,35A.
Where I am lost is the size of capacitor.
Can somebody point me in the right direction please.

Thanks,
Michiel

[A.L.]

hello,

Where I am lost is the size of capacitor.
Can somebody point me in the right direction please.

you might want to start with this thread - www.navitron.org.uk/forum/index.php/topic,2844.msg25642.html#msg25642

there is a formula linked here - www.navitron.org.uk/forum/index.php/topic,5847.msg76042.html#msg76042