"G83 relays" and such

[evan]

Hi All,
  We have a variety of renewable stuff working (two 1kW grid connect PV installations, a 100W Navitron water turbine charging batteries, solar hot water etc) and recently completed a 3 meter wind turbine (let's say 1kW).  It has an electrically operated brake which is controlled on overspeed.  It has a single phase induction motor as the generator. 

I was possibly a bit optimistic when we started this and am now starting to worry about how to legally connect it, in a cost effective way.

I was assuming a G83 relay, for a few hundred pounds, and a contactor. 
Searching around I can't find anything either cost effective or compatible with single phase. 

Have I gone wrong here?  What options have I got?

Thanks!

[Ted]

Hello evan, welcome to the forum.

Whenever you connect any small generation system to the grid you must advise your DNO (Distribution Network Operator) that you have done so (you must seek their permission before doing so in the case of > 6kW systems). You must provide them with the appropriate certification, diagram and commissioning forms that describe what components make up the system and confirm that the system complies with the rules laid down in Engineering Recommendation G83/1. It is the responsibility of the DNO to contact your supplier so that they can ensure that the meter fitted to your premises correctly records your power usage (i.e. can't spin backwards when you export to the grid).

If they are not satisfied that your system is safe or that it does not comply with G83/1 or BS7671 (the Wiring Regs), then they are entitled to disconnect you from the grid, under the terms of The Electricity Safety, Quality and Continuity Regulations, until such time as they are satisfied. 

What inverters have you used on the PV system?  Is the new wind turbine connected to the grid or just charging batteries?

[evan]

Hi Ted,
  Thanks.

Whenever you connect any small generation system to the grid you must advise your DNO (Distribution Network Operator) that you have done so (you must seek their permission before doing so in the case of > 6kW systems). You must provide them with the appropriate certification, diagram and commissioning forms that describe what components make up the system and confirm that the system complies with the rules laid down in Engineering Recommendation G83/1. It is the responsibility of the DNO to contact your supplier so that they can ensure that the meter fitted to your premises correctly records your power usage (i.e. can't spin backwards when you export to the grid).
If they are not satisfied that your system is safe or that it does not comply with G83/1 or BS7671 (the Wiring Regs), then they are entitled to disconnect you from the grid, under the terms of The Electricity Safety, Quality and Continuity Regulations, until such time as they are satisfied.

Yes, I'm fully conversant with all this

What inverters have you used on the PV system?

SMA and Fronius.

Is the new wind turbine connected to the grid or just charging batteries?

It's an induction motor so needs to be connected to the grid. 


My question was: is a single phase "G83 relay" available affordably?  If not, what other options do I have? 

[martin]

I have a feeling that there's a bit of a misapprehension here. As far as I know, there isn't such a thing as a "G83 relay" - there are G83 inverters, but they are loads more complicated than just a relay. In simple terms a G83 grid tie inverter senses at all times that there is current arriving from the grid, or it will disconnect (save frying the lineman up the pole trying to repair the faulty line) - then it will officiate over the "initiating rhumba" to ensure that what you're shovelling up the line is properly "in synch", having "cleaned up" whatever you're producing. You'll need a pukka grid-tie inverter of appropriate size for your wind turbine output to connect it to the grid.......

[evan]

I have a feeling that there's a bit of a misapprehension here. As far as I know, there isn't such a thing as a "G83 relay"

Something like this:
http://www.solar-relays.com/protection-relays-spr100

Or any other device or collection of things set to the appropriate voltage and frequency limits, I guess.


But I need a single phase one, or some other option.  Anyone?

[martin]

As Ted explained, to legally connect ANY current to the mains you have to use a G83 grid-tie inverter - and as I explained, it isn't a simple as a relay - to do it, you need a pukka G83 grid-tie inverter..........

[evan]

As Ted explained, to legally connect ANY current to the mains you have to use a G83 grid-tie inverter

Surely, legally speaking, you have to comply with G83.
I'm aware that using an inverter (with a suitable generator) is the off-the-shelf option, thanks.

- and as I explained, it isn't a simple as a relay

The link I posted above is a relay, albeit not a particularly simple one.

[martin]

you've asked for option(S) - it is singular - one option - G83 grid-tie inverter
I presume you already have pukka inverters for the pvs?

[evan]

you've asked for option(S) - it is singular - one option - G83 grid-tie inverter
I presume you already have pukka inverters for the pvs?

No, SMA and Fronius.

Thanks for the help anyway.

[martin]

SMA and Fronius ARE pukka (meaning correct, the right equipment)

[Alan]

Hello Evan

I am not aware of any single-phase relays that are certified to G83.  Using a motor as a generator is do able, with a reasonably constant torque device like a diesel engine or water turbine where the ability to keep the speed just above synchronous is quite straightforward.  Because the wind tends to gust its not so straight forward on a wind turbine. Providing the swept area of the blades is a lot less than the motor capacity you would be in with a chance. The losses involved with the device being driven from the mains supply when the wind speed is low is also not good.  I would suggest a modification with a P.M.A. is the way to go.

The relay to make is very easy, but satisfying the requirements of G83 and the E.M.C. testing required selling it in Europe would be costly.

Regards

Alan

[evan]

Hello Evan

I am not aware of any single-phase relays that are certified to G83.

Hi Alan, OK thanks for that, seems to confirm what I found.  Still, maybe someone else knows of one, I live in hope

Using a motor as a generator is do able, with a reasonably constant torque device like a diesel engine or water turbine where the ability to keep the speed just above synchronous is quite straightforward.  Because the wind tends to gust its not so straight forward on a wind turbine.

I'm not sure I agree - the induction machine (if connected to the grid) will hold the speed down, as the wind speed increases the blades will stall and this will continue unless the torque input exceeds the breakaway torque (or until the generator overheats).

The losses involved with the device being driven from the mains supply when the wind speed is low is also not good.

Indeed, but this problem is fairly easy to overcome.

The relay to make is very easy, but satisfying the requirements of G83 and the E.M.C. testing required selling it in Europe would be costly.

Yes, agreed.  I wasn't considering making one for that reason, and was hoping someone else already had (such as the solar relay above) or explore the possibility of using separate already manufactured relays programmed to the appropriate settings.

Cheers!

[knighty]

exactly which inverters are you already using ?

could you not rectify your wind turbine power to DC and feed it into one of those ?

[evan]

exactly which inverters are you already using ?

could you not rectify your wind turbine power to DC and feed it into one of those ?

Hmm, a single-phase induction motor is difficult to use as a generator stand-alone, and feeding a rectifier I doubt it would work at all well, and there would be issues about regulating it too.  I would need to convert it to a PMDC machine to do that really.

The inverters are also in use a fair amount of the time (although not at night, granted), and the MPPT algorithm of the PV inverters doesn't tend to work very well with a wind turbine.

So I'd be looking at an additional windy-boy as well as a lot of work to turn the machine into PMDC.  That's why I'm trying to make it work as designed first..



What I might do is dig the "Grid OK" signal out of the SMA and use that to work the contactor for the wind generator. 

[Ted]

evan, I assume you've read the other threads on here where the subject of grid connecting induction generators (hydro and CHP but not wind) has cropped up.  Using the 3-phase G83 relay is the only real solution I've seen - but this won't work with single phase (or so the manufacturers are quoted as saying). There doesn't appear to be a single phase version of such a relay on the market, presumably because such a market is a very small one and hence uneconomic for a manufacturer to produce one. The option of putting some components together yourself and getting them G83 certified is similarly uneconomic. Sorry, that doesn't help you very much.

I presume you are OK with getting the PV system accepted by your DNO if it is not already?