Jump to content

vde-ar-n 4105 - AC coupling OFF Grid


phil.g00

Recommended Posts

I have been reading some details about the German standard vde-ar-n 4105 which I understand replaced the standard vde 0126-1-1.

I think there is a more recent vde standard than these, but:

One of the key differences I see, is the later standard requires the limiting of inverter power output by 40% per Hz starting at 50.2Hz  with a complete disconnection at 52Hz.

While the earlier "0126" standard directed a complete disconnection at 50.2Hz. This all but ruled such an inverter out to be capable as a back-up inverter in an AC-coupled off- grid set up.

Now, I know ABB, Fronius, and SMA  can be back -up PV inverters, and they market this capability.  These brands offer zero export capability, normally by use of a proprietary meter at the point on disconnection and various protocols when AC -coupled with a Bi-directional inverter/charger.

I don't want to get into those premium brands, I want to talk about an OFF grid situation and power control by the frequency shifting capability of the bi-directional inverter.

It would seem to me in an off-grid situation, if the german grid code setting was selected that a "4105" compliant PV inverter would be frequency shifting capable.

And this would make it fairly suitable to be an ac-coupled backup inverter in an off grid setup.

There are quite a number of lesser known brands that are actually "4105" certified, but there is normally no mention of this back up capability.

(And by lesser-known I mean seriously less expensive).

Has anybody any experience of putting a lesser known "4105" certified inverter in this scenario?

 

Link to comment
Share on other sites

2 hours ago, phil.g00 said:

Has anybody any experience of putting a lesser known "4105" certified inverter in this scenario?

All I can tell you is that with the Fronius we have to select "MG50" (microgrid, 50Hz) as the country code to make it work in, well, microgrid situations. I can also tell you that without proper support for this, a Fronius just doesn't tie properly with a Multi. So with all due apologies for mentioning two premium brands, I think that is enough evidence that one cannot conclude that mere VDE-AR-N-4105 compliance guarantees stable operation off-grid. Yes, frequency shifting will work... but anti-islanding might be too strict and cause repeated nuisance tripping of the PV-inverter.

Link to comment
Share on other sites

@plonkster, I specifically remembered you mentioning this, and i am glad you responded.

I do want to point out that a mere compliance is not what I mean, as these inverters are compliant with a whole range of country codes.

It would take actually selecting  the "4105" country code as well. In your experimentation can you recall if you did that?

Link to comment
Share on other sites

23 minutes ago, phil.g00 said:

It would take actually selecting  the "4105" country code as well. In your experimentation can you recall if you did that?

Nope. It arrived as part of a whole test setup. Someone had already set it up. It never worked properly, and somewhere along the way I probably made it worse with a firmware update. I only learned about this stuff a few weeks ago when I was actually tasked with testing the new Fronius firmware. So I never specifically tested any grid code.

Link to comment
Share on other sites

@plonkster, You see, and we're sort of touching on it on another thread, the first standard was very stringent and all 0126 certed inverters switched off en masse  at 50.2 Hz, - which was no good for grid stability.

So the way I see it the clever Germans took a threat and turned it into an opportunity and so now instead of the standard creating grid instability, the sliding scale actually used to foster grid stability. No big step change, but a gradual ebb and flow bringing a frequency event back to 50Hz.

But, I do think other countries may well be behind this curve, so if you had it set on a different country code you could well have been dealing will the all or nothing very strict limits.

In which case your right it would very finicky.

Now here's what I am hoping, the big boys are actually using this "Microgrid" setting to deploy what is in fact already there in "4105" or some other standard.

The Aus standard, I believe is power 100- 0% between 51 and 52 Hz.

Do you perchance know the Microgrid  freq/power ramp  in Victron?   -- it might be even more liberal.

 

Link to comment
Share on other sites

1 hour ago, phil.g00 said:

Do you perchance know the Microgrid  freq/power ramp  in Victron?   -- it might be even more liberal.

Right, just be careful of the word "ramp". Normally that means how fast you are allowed to go from 0% to 100%. Both Germany and Australia have ramp rates.

The Victron inverter will simply keep increasing the frequency until such time as the power level drops sufficiently. So there isn't an exact scale, nor is it required. As long as the PV-inverter switches off completely at 53Hz (above 52.7Hz in practical terms) it works fine. When you configure the ESS assistant it does allow you to enter different values though.

Link to comment
Share on other sites

Yes, quite right I didn't mean to imply that there is an expectation of  X power output decrease for X frequency rise by the Victron, its just working on the feedback response of the MicroGrid.

By changing a setting in the Fronius though it may also flatten out its ramp to be more in tune with Victron also up to 52.7hz.

Then the marriage would appear more stable, because there is a bit more leeway to deal with bumps.

 

 

Link to comment
Share on other sites

Pictures shows the default Multiplus ESS settings with the Fronius frequency range.

I've sent the default 50.2Hz to 51Hz, not sure if this is correct.

My Fronius works when there is a pwer failure as a MG, but trips out when the mains returns? 

ess.png

fronius.png

Link to comment
Share on other sites

52 minutes ago, vandyh said:

My Fronius works when there is a pwer failure as a MG, but trips out when the mains returns? 

When the grid returns, the Multi does a quick frequency sync to reconnect to the grid. To the PV-inverter this looks like an islanding event (it probably trips the RoCoF bit... or perhaps it is considered a vector shift, I'm not sure). The alternative (technically speaking) would be a longer grid-sync time, so it would take longer to reconnect the grid, or to make the PV-inverter even less sensitive to islanding events (which is probably the worst solution of the lot).

Link to comment
Share on other sites

44 minutes ago, anotherbrownbear said:

On the ABB inverters you only have some minor settings to do to enable FS power derating.

Does the ABB Off-grid FS power derating rate differ greatly from the VDE4105 standard of 40% decrease per Hz increase starting at 50.2 Hz?

In other words is it more tolerant than any grid code setting?

Link to comment
Share on other sites

3 hours ago, anotherbrownbear said:

On the ABB inverters you only have some minor settings to do to enable FS power derating. Picture added is running off grid at the moment until the onsite sparky can bring the main supply cable over to the building.

image_8c662c65-6c74-47c7-bb88-1031fea1f27320190124_160716.jpg

Very neat cable installation, I like!

Link to comment
Share on other sites

2 hours ago, plonkster said:

When the grid returns, the Multi does a quick frequency sync to reconnect to the grid. To the PV-inverter this looks like an islanding event (it probably trips the RoCoF bit... or perhaps it is considered a vector shift, I'm not sure). The alternative (technically speaking) would be a longer grid-sync time, so it would take longer to reconnect the grid, or to make the PV-inverter even less sensitive to islanding events (which is probably the worst solution of the lot).

I will hookup my power analyser and capture the event. post it here.

Changing setting in the Fronius requires special access codes. 

Link to comment
Share on other sites

2 minutes ago, vandyh said:

Changing setting in the Fronius requires special access codes. 

This one isn't that special. You hit the third button from the left 4 or 5 times, and then you enter 73887, pressing enter to enter each number and then enter again to confirm at the end. That gets you into the country selection part.

But you are right that changing other settings requires a code for the Profi menu. I actually have a code for mine and I've mucked around in there a bit. You do have to know what you are doing. Other than the ramp rate and maybe playing a bit with the allowed voltages (eg in some parts of Australia a cap of 255V is a bit low), the rest of the stuff probably should be left alone 🙂

Link to comment
Share on other sites

2 hours ago, phil.g00 said:

Does the ABB Off-grid FS power derating rate differ greatly from the VDE4105 standard of 40% decrease per Hz increase starting at 50.2 Hz?

In other words is it more tolerant than any grid code setting?

You can have a look at the attached white paper. it is a bit out dated but the principle is still the same. One big change on the newer inverters is the fact that you do not have to ude VDE or CEI grid settings. The OF derating settings are opened with a 2nd level password, that I can retrieve, on any grid code. These settings can be matched to what Victron, or whoever is capable of this, suggest.

Inv_Str-All_OFActivePowerLimitation_2015-06-26.pdf

Link to comment
Share on other sites

17 minutes ago, anotherbrownbear said:

One big change on the newer inverters is the fact that you do not have to ude VDE or CEI grid settings. The OF derating settings are opened with a 2nd level password, that I can retrieve, on any grid code. These settings can be matched to what Victron, or whoever is capable of this, suggest.

This seems ideal, a couple of questions for clarity though:

1. When you say these "newer inverters" do you mean this custom "derating" facility is available in these 2015 models (mentioned in the paper) and later?

2. Is the facility available to installers for off grid installation who may want to harmonize a pairing with a third party hybrid inverter?

Link to comment
Share on other sites

10 minutes ago, anotherbrownbear said:

Now it is available on any grid code.

And it's available for tweaking by the installer?

If so, I am going to get me a little one to play with in a small off-grid setup. These ABB inverters are shaping up to be strong Fronius competition.

Link to comment
Share on other sites

1 minute ago, phil.g00 said:

And it's available for tweaking by the installer?

If I understand @anotherbrownbear correctly, it probably works the same as with the Fronius. You email tech support with the serial number of your device and ask for an access code. They have some one-way hash thing they use to generate the access code for your device and they send that back. And they make a note in their system that you meddled with it... in case of warranty claims... 🙂 I'm kidding. But they do take note of it, for legal reasons, so that they can't be blamed if something goes wrong while you were operating outside of accepted grid-code parameters.

Link to comment
Share on other sites

5 minutes ago, plonkster said:

If I understand @anotherbrownbear correctly, it probably works the same as with the Fronius. You email tech support with the serial number of your device and ask for an access code. They have some one-way hash thing they use to generate the access code for your device and they send that back. And they make a note in their system that you meddled with it... in case of warranty claims... 🙂 I'm kidding. But they do take note of it, for legal reasons, so that they can't be blamed if something goes wrong while you were operating outside of accepted grid-code parameters.

100% correct. Only in this case, we have online access to get the code as AVP. We then keep record of all the serial numbers etc. of where our products go.

Link to comment
Share on other sites

2 minutes ago, plonkster said:

If I understand @anotherbrownbear correctly, it probably works the same as with the Fronius. You email tech support with the serial number of your device and ask for an access code. They have some one-way hash thing they use to generate the access code for your device and they send that back. And they make a note in their system that you meddled with it... in case of warranty claims... 🙂 I'm kidding. But they do take note of it, for legal reasons, so that they can't be blamed if something goes wrong while you were operating outside of accepted grid-code parameters.

So do you get ability with Fronius to harmonize/de-harmonize the "Power derating" as well in the settings?

I can see this being very useful.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...