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Topic Title: PV Solar Farm EMC issues
Topic Summary: Does anyone have any experience of EMC problems adjacent to large solar PV installations?
Created On: 11 July 2013 02:54 PM
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 11 July 2013 02:54 PM
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JMR

Posts: 17
Joined: 17 April 2002

Plans are being discussed to build a large solar PV system on a 200 acre green field site immediately adjacent to the farmhouse property I own. This will be a 12MW total scheme, feeding into the 33KV grid via 12 off 1 MW invertors.

Does anyone have any experience of the EMC, audible noise, and mains interference problems this may cause and what can be done to mitigate the problem?

John Reid FIET
 11 July 2013 09:11 PM
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jcm256

Posts: 1834
Joined: 01 April 2006

Sorry to hear that, 200acres of arable land lost, for what someone's greed, it will not reduce the cost of electricity that's for sure, the pensioners and fuel poor as will all of us have to pay extra for the day time electricity it produces. Next to a farm, insist the panels come with an Ammonia Resistance Certificate.

Regards
jcm
 16 July 2013 02:32 PM
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haguetim

Posts: 109
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John, I think that there is a good chance that you will get interference from the inverters. As regards to the EMC Regs, the inverters are tested for conducted emissions below 30MHz but not radiated, a crazy situation looking at the frequency of the switchers.
You might be able to get more information from the RSGB.
 23 July 2013 03:29 PM
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JMR

Posts: 17
Joined: 17 April 2002

Thanks for the RSGB lead tim. - At these high powers I too think that there will be a lot of radiated RF noise. I wonder if any existing sites have already caused problems - I have heard vague rumours via amateur radio sources.

A colleague has also suggested we may experience a significant increase in our supply voltage when the scheme is powering the grid. - Does anyone have any direct experience?

John
 23 July 2013 07:08 PM
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JonathanHill

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The Voltage rise will depend on the impedance of the network you're connecting into, as well as the power level.

If you do experience excessive Vrise, if the network has a high X/R ratio, you may be able to suck some reactive power to reduce this.

It really needs a study to determine.

-------------------------
Jonno
 31 July 2013 12:45 PM
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JMR

Posts: 17
Joined: 17 April 2002

Thanks Jonathan

I'm already connected and this is a proposed development over which I have no control!

I'm very keen to get some feedback from anyone who has direct experience of the high power invertors used on these large PV schemes.

I would also welcome any ideas on how we might go about preventing this 12MW (200 acre!) greenfield development from going ahead.

John
 31 July 2013 01:58 PM
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jarathoon

Posts: 1040
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John Reid,

I would support the farmer being able to install PV on a scale to meet their on farm energy needs, with any surpluses sold on to the grid (I suspect a development on the order of 500 kW would more than suffice for this, preferably on farm building roofs). I do not support should giving solar subsidies so farmers can turn farm land into vast solar electricity power stations. If the government wishes to heavily subsidise large scale solar developments there are plenty of warehouse roofs to be used prior to farm land being taken up in this way.

If the farmer grows biofuel crops or simply hay that can be put in an anerobic digester they in effect create energy (diesel or biogas) which can be stored and used in the winter. This is a far more valuble service to provide, if the farmer wants to get in the energy business.

In general I would support farmers in using new technology and support them to diversify and employ more people in rural areas e.g. polytunnels, greenhouses, free range chicken sheds, anerobic digesters, farm produce shops etc. This is so we can hopefully begin to reduce farming subsidies over time.

I think we (the IET) should definitely say something about where we feel the right balance lies on this including technical standards for inverters. I think in this process you must say what you think is reasonable for your neighbour to do in terms of diversified farming development, otherwise your arguments may well be dismissed as those of a self-serving nimby. You can then send a document outlining all this to your local council for the elected councillors to pass judgement.

James Arathoon

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James Arathoon
 31 July 2013 09:27 PM
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JMR

Posts: 17
Joined: 17 April 2002

Thanks for the comments James - I think your remarks are most pertinent.

I think this whole issue might become very high profile soon, as several big schemes have recently been completed and the visual impact is now becoming apparent. Only today, a full page article by Griff Rhys Jones has appeared in the Daily Mail (very good summary of the issues) and I too feel that the IET should have a say in this.

Is it too obvious to point out that:

These schemes don't generate at night.
We don't need the (very expensive) additional power during the day.
It is not economically feasible to store the "surplus" power.
Every MW of solar/wind needs the same capacity on conventional standby (and that also costs money)
Virtually all the capital equipment spend goes to the far East.
UK contribution to world carbon emissions is insignificant.
Without government subsidies (ie from us) the whole thing is commercially non-viable.
One nuclear power station is equivalent to about 25,000 acres of PV panels. (someone please check!)

I could go on, and I'm sure so could you.

Come on IET and offer some proper thought out guidance to government!

Here is the link to the DM article:
http://www.dailymail.co.uk/deb...urite-landscapes.html

John Reid

Edited: 31 July 2013 at 09:48 PM by JMR
 13 November 2013 04:57 PM
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JMR

Posts: 17
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It looks like this is now going forward to planning so the heat is on! - Any help in stopping this will be greatly appreciated!

With reference to the comments above by Tim Hague on radiated emissions (lack of a test specification) the developers have now sent me a CE Declaration of Conformity from "Power Electronics" which refers to: 2004/108/CE (EMC), EN 61000-6-4-2007 (EMC generic standards - emissions), and IEC 61000-3-4-1998 (EMC emission of harmonic currents).

I am also concerned about "voltage lift" as we are in an isolated position quite a way from any other habitation and our 415V supply transformer is only about 200 metres from where they propose to feed up to 12MWp into the MV supply. This of course will reduce to zero when it goes dark!

Does anyone out there have any experience of what impact these big "Solar Farms" can have?
 13 November 2013 08:55 PM
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statter

Posts: 124
Joined: 06 February 2013

The dno should look after voltage regulation. In most places your 415v supply will be off an 11kV network fed from the 33kVnetwork. There is normally voltage control by tapchanger at the 33 to 11 sub. Also IIRC the engineering recommendation requires maximum disturbances to be met which often dictates where the point of common coupling with the rest of the network should be.

There are some 33kV to LV supplies but these are very rare. Why not speak to the DNO tech people?
 18 November 2013 04:57 PM
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JMR

Posts: 17
Joined: 17 April 2002

Thanks statter - from what you say it looks like it is an 11KV supply, in which case the problem will be even worse! I have not seen a local 33 to 11 substation so there must be a mile or two of 11KV cable at least.
 18 November 2013 08:26 PM
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statter

Posts: 124
Joined: 06 February 2013

I'd be surprised if dno connects 12MW solar at 11kV unless very near a 33/11 SMS with a good fault level. Your OP says 33kV connection anyway. With a mile or two of ohl I'd say that they will run a 33 kV line back to the nearest primary ss.
IET » Energy » PV Solar Farm EMC issues

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