I recently switched from a Multiplus 2 5000 to the Multi RS. Since updating the Multi RS to firmware 1.26 almost everything works as expected now. I did a lot of tests during the last days and found a strange behaviour when changing the grid setpoint.
I use the grid setpoint to control my grid feed in and change the value every minute based on a Home Assistant automation. Updated values are sent via MQTT (topic W/…/multi/0/Ess/AcPowerSetpoint). While the Multi RS processes load changes almost instantly (faster than the Multiplus), it needs a lot of time to adjust its feed in to match changed grid setpoint values, e.g. it needs about 40 seconds when the setpoint is changed by about 1000 W, 80 seconds when the setpoint is changed by about 2000 W, etc.. The Multiplus only needed ~5% of that times.
Is there any setting that has an impact on the processing speed of grid setpoint changes?
My setup: 1x Multi RS on L1, VM-3P75CT (firmware 1.10) connected via VE.Can, German grid code
Yes, my Multi RS seems to have a hard coded limit of ~26W/s. I did another test this afternoon and changed the value from -7000W to 0W and it took about 4min 30s to reach the 0W. I guess that this is related to the German grid code. As far as I know German VDE regulations define a max change of 400W/s on the grid side (this was also the reaction speed I had with the Multiplus) . The German grid code configuration of the Multi RS may have an incorrect max value.
I can confirm that this is a bug in the German grid code. I changed to the European grid code for a short test and the Multi RS adjusted the feed in almost instantaneously.
As there is no direct contact option and I don’t want to handle this via my dealer, I changed the title and hope that somebody of the Victron staff takes care of it.
Das ist immer wieder falsch. VDE AR-N 4105:2024:10 gibt 3 Tau für 10 Sekunden und 95% des Endwerts an. Nicht nur für die Blindleistung sondern an anderen Stellen auch für die Wirkleistung. Macht auch mehr Sinn als eine lineare Änderung.
That is a requirement from the German grid code standard VDE-AR-N 4105, it states that the rate of change of energy supply and/or consumption must be limited between 0.33% and 0.66% of the rated power per second.
Thank you @thiemovanengelen . However, as you can see in the screenshot of the VDE AR-N 4105:2024:10 @Janvi posted, both the 400W/s I mentioned and the rule “consumption must be limited between 0.33% and 0.66% of the rated power per second” you posted are not correct.
Please note that the current implementation makes the Multi RS hardly usable in Germany for certain use cases and that the adjustment speed of the Multiplus is almost 20x faster, although both should follow the same VDE rules.
Regarding the screenshot, this specifies the reactive power behavior. Article 5.7.4.1 specifies the active power output and this contains the mentioned limitations.
@thiemovanengelen Thank you for your support! You are right, that article 5.7.4.1 of DE-AR-N 4105:2024-10 contains the mentioned limitations. However, I see two problems:
DE-AR-N 4105:2024-10 is still in draft state and not final yet.
If I understand article 5.7.4.1 correctly, those limitations only have to be applied in case the setpoint is changed by a third party. I actually don’t think that I am a “third party” in my use case.
Maybe there are some VDE experts in the community that know more about this rule that is described in article 5.7.4.1.
Thank you @Thiemovanengelen for the 0,33/0,66% hints. Here is the complete AR-N 4105 draft. The rules for change of P between 0,33 an 0,66% are described in page 46 Chapter 5.7.4.1. Unfortunately, the final versions are not allowed to discuss in public for copyright reasons. Nevertheless, the release do not contain much difference with the draft versions.
My last final AR-N 4105 is issue 2011-08 updated in November 2018 with 96 pages. Page 33 contains the very same illustration in “Bild10” than posted before. As far as I know, attached draft from October 2024 is official release in the meantime.
Similar requirements with 3 Tau for 10 seconds are repeated in the document “FNN Hinweis - Anschluss und Betrieb von Speichern am Niederspannungsnetz” up from page 18
None of this documents contain any rules with 400 Watt/sec !!!
For a 3xMp2 5k Installation 0,66% would be a change rate of only 100W/sec only (0,66% of 15kVA) but this thread is for Multi-RS not MP2. Maybe this is true after the first grid sync but later its luckily faster.
Pls note, that there are more definitions of exceptions to the 0,33/066% rule what require faster reactions within the 10sec time. This is any Pav,e supervisor what limits the grid feed in by switching appropriate loads. With other words: Switching loads must not produce overshoots worster than 3 Tau. We cannot meet setpoint errors <10% after 3 seconds with any 400W/s or 0,33/0,66% change limit.
The Multiplus had firmware version 510. As the release notes of newer versions didn’t mention any changes that were relevant for my system (also no changes of the German gridcode btw), I never had the need to update to a newer version.
