Batrium SMA Sunny Island Integration issue?

[1201]

Just gave the inverters a 1500w load for 2+ minutes. Battery took 100% of the load and after about 2 minutes the PV took the load and was charging the battery as well. Removed load at 3 minutes and now it is ramping the charging back down. Still indicating float mode. SOC post ramp down is 77.9

So looking at book, the compact meters page. Current set point of charging voltage is 53.7, actual voltage 53.0, active charging process FLOAT
Error SOC is 4.9 ... this with float voltage set to 2.3 which if the math is right should be 55.2vdc

If float is 2.3 that's 55.2v

Did you increase battery charging amps?

Do you have your battery set to 23 cells or 24?(46v or 48v)

 

[Hedges]

100% offgrid with gen backup set
...
SB is not connected to the SI via COMMs so it uses phase shifting to communicate. (On that note I have seen the SB "turned off" by the SI, if I recall it will throw a local error code on the SB saying something which indicates AC out of range ... this while the battery is still < 95% and the sun is out :/ )

Is SB set to UL-1741, to Rule-21, or to Island?
I'm guessing Rule-21, in which case could behave better with Island, i.e. not be turned off.

UL-1741 would drop off without ramping down power.
Rule-21 would ramp down to 0% at 61 Hz, but might drop off above that.
Island would ramp down to 0% at 62 Hz but not disconnect below 64 Hz.

Turn afra enable off.

I think the sunny island will not output power at 58.9hz.

If you turn afra enable off frequency won't go below 60 and you should start charging again

SI will make excursions down to 59.0 Hz to mechanical timers remain on time despite being above 60 Hz for a while (and overshoots frequency whether going up or down.) Can be turned off as you say.

SB UL-1741 will disconnect below 59.3 Hz.
Rule-21 will disconnect below 58.5 Hz, but not for 59 Hz or 58.9 Hz.
Island will remain connected down to 64 Hz.

For an older SB not supporting Rule-21, I changed lower frequency limit to 58.5 Hz.

 

[callmeburton]

I will have to go over to the panels and check on the SB settings. It is a 7.7 US-41 though. I forget if I went with. I will run out there in a sec and look. Scratch that, I don't have the required laptop here to do that ... my current one doesn't have a hardwired input :/

Battery is set 48vdc for VLRA, and when I went to disable AFRA the battery was charging a little but again still around 77.9% SOC overall ... we have a slightly larger load on the system right now so maybe that triggered the change idk.

RE: AFRA ... had to look that one up. 12.7 Automatic Frequency Synchronization ...
I thought the SI needed to control the SB via frequency control (FSPC) to avoid issues? I assume this doesn't affect that.

 

[kommando]

I assume this doesn't affect that.

Correct, SB's only respond to over frequency, they ignore the under frequency until its much lower than the clock correction and then just disconnect assuming a grid fault.

 

[Hedges]

Frequency shift to higher frequencies curtailing PV still works.
AFRA is balancing that time & frequency with equal amount at low frequency (59 Hz.)

"12.7 Automatic Frequency Synchronization
Clocks that depend on the stability of the power frequency for their accuracy become increasingly
inaccurate when there are constant frequency deviations. Frequency fluctuations, i.e., deviations from
the nominal frequency occur, for example, in off-grid systems that operate with a diesel generator.
The automatic frequency synchronization (German: AFRA) function of the Sunny Island allows the use
of clocks in these types of off-grid systems. This function is activated using the parameter
"250.11 AfraEna". The time deviation is compensated on average."

Correct, SB's only respond to over frequency, they ignore the under frequency until its much lower than the clock correction and then just disconnect assuming a grid fault.

Unless SB set to UL-1741; in that case, 59.3 Hz lower limit isn't low enough to remain connected when SI drops to 59 Hz. It will overshoot a bit further, like 58.9 Hz before settling back to 59 Hz.

Rule-21 allows 58.5 Hz and remains connected.

If no grid connected, you want Island settings, even wider frequency and voltage. Also doesn't wait 5 minutes to reconnect, I don't think.

 

[1201]

Its on the sunny island side. If the battery is not full, ie not to target voltage it should be charging at full allowed capacity so if it's not it's because the sunny island is throttling output. Check your frequency. It should be 59.99 or 60hz. If it's higher than that it's throttling output and if it's higher than 60.5 it's probably shutting off the sunny boy.


Raise your battery charging amps!

 

[callmeburton]

Did you increase battery charging amps?

It is at 65 now, but it hasn't come close to approaching this. When the BMS controlled the charging I could easily get 95% every day but the timeout is the issue :/

 

[Hedges]

Higher than 60.5 Hz shuts off UL-1741
Higher than 60.5 Hz throttles Rule-21
61 Hz drops Rule-21 to zero
Higher than 61 Hz shuts off Rule-21
Higher than 61 Hz throttles Island
62 Hz drops Island to zero
Higher than 64 Hz shuts off Island

 

[callmeburton]

Next time it starts to dump something into the battery I will see how it throttles off ... I can't check SB settings likely till next week as it requires me to go home to get the laptop I need.

 

[Hedges]

Does SB display settings at power up? I've only briefly played with -41 model so far.
DMM showing frequency will show where it is operating, maybe what frequency it briefly hits. That will indicate what settings.
You want it to hover at some elevated frequency with SB putting out reduced power.

 

[callmeburton]

Ok, just went through a 7 minuteish cycle of charging.
It started to throttle at 60.5 and got to 0 output at 61.5

 

[callmeburton]

Does SB display settings at power up? I've only briefly played with -41 model so far.

I dont' think so https://ressupply.com/documents/sma/SB_3.0-7.7-US-41_User_Manual.pdf pg22 has the screen outputs.

 

[1201]

It is at 65 now, but it hasn't come close to approaching this. When the BMS controlled the charging I could easily get 95% every day but the timeout is the issue :/

Raise it more! Charging at 1c for 10 minutes is not going to hurt your battery. We need to know if that's the issue

 

[Hedges]

Ok, just went through a 7 minuteish cycle of charging.
It started to throttle at 60.5 and got to 0 output at 61.5

If I'm not mistaken, to throttle at 60.5 (but still deliver power), at least some of your SB are set to Rule-21.
How many SB, and what models?

Zero output is too low for "Island" setting, that would give 50%

61.5 Hz would cause Rule-21 inverter to drop off (maybe instantly, not sure.)
By the time SI raised frequency to 61 Hz, SB with Rule-21 is supposed to be down to zero, but maybe delayed response plus SI overshooting since it didn't see power drop fast enough.

Short term, try adding an AC load like a space heater. Not sure if that will affect response of control loop. What it should do is allow frequency to settle below 61 Hz, keeping SB Rule-21 on line.

I think it will work better with "Island Mode 60" or whatever the offgrid setting is called.
What I don't know about is how your lithium cells respond in voltage to charge current, or how BMS behaves.
I would like BMS to allow brief excursions above target voltage without disconnecting, that should allow SI time to frequency shift and SB time to respond, so charge current is adjusted and battery voltage oscillates then stabilizes at target value.

Look into whether BMS has "time" settings as well as "voltage", for over-voltage shutdown.
Set SB to Island mode.
Consider changing curtailment frequencies of Island mode. Default is 100% at 61 Hz, 0% at 62 Hz. Try 100% at 60 Hz, 0% at 61 Hz or 60.5 Hz (but keeping 64 Hz max without disconnect). Eliminating the dead band should reduce delay before curtailment.
Consider disabling AFRA, so inverter doesn't go below 60 Hz to 59 Hz, again eliminating dead band.

 

[kommando]

Frequency shift profile, the SI moves from 0 to +1 Htz as it nears the point of limiting but the SB should not react until the SI goes over the +1htz.

 

[callmeburton]

Raise it more! Charging at 1c for 10 minutes is not going to hurt your battery. We need to know if that's the issue

I don't see what this is testing for if the SI won't go above say 30A when charging right now, I say right no as if the batter was lower in voltage (currently 53.4 I think) I Have seen it max out at the amps set.

I set it to 140 which should be .5C

Look into whether BMS has "time" settings as well as "voltage", for over-voltage shutdown.

My BMS is isolated ... the only thing it can control is a relay which would 100% disconnect the SI ... this only happens if the battery is at serious risk. So right now the BMS is doing nothing to communicate to the SI its current state or desires for the battery.

Short term, try adding an AC load like a space heater.

I will get my paint stripper going and see what it does. Currently when not charging with the AFRA disabled the Hz bounces between 59.9 and 60.0

 

[callmeburton]

Frequency shift profile, the SI moves from 0 to +1 Htz as it nears the point of limiting but the SB should not react until the SI goes over the +1htz.

yeah I saw that in the book as well ... not sure if distance plays a part but the panels are a good 300ft from the SI inverters.

 

[kommando]

not sure if distance plays a part but the panels are a good 300ft from the SI inverters

Makes no difference at all.

 

[callmeburton]

How many SB, and what models?

one, SB 7.7 US-41

 

[Hedges]

Frequency shift profile, the SI moves from 0 to +1 Htz as it nears the point of limiting but the SB should not react until the SI goes over the +1htz.

That is default Island (offgrid) parameters.
Rule-21 is different.

yeah I saw that in the book as well ... not sure if distance plays a part but the panels are a good 300ft from the SI inverters.

Distance to panels won't matter at all.

My BMS is isolated ... the only thing it can control is a relay which would 100% disconnect the SI ... this only happens if the battery is at serious risk. So right now the BMS is doing nothing to communicate to the SI its current state or desires for the battery.

OK, so long as it isn't disconnecting, this is all about SI, frequency shift, SB response.

I will get my paint stripper going and see what it does. Currently when not charging with the AFRA disabled the Hz bounces between 59.9 and 60.0

59.5 to 60 Hz is no curtailment, SB delivers 100%. Which has to go to loads or battery.

one, SB 7.7 US-41

OK, I am only starting to play with mine.
Others (e.g. SilverbackMP) use that model, set for Island.
That is what you should do.