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rodgerd avatar image
rodgerd asked

AC Coupled inverter on AC-OUT with export limiting to the INVERTER!

I am busy with an off-grid installation that has a Goodwe GW15KN-DT PV inverter on AC-Out of a set of Quattros. The PV Inverter assistant is configured and frequency shifting works as expected as the battery approaches full. The Goodwe is supposed to be VDE4105 compliant and the suppliers assured me before purchase that it was able to reduce power in response to frequency shifts. In practice the Goodwe does not respond appropriately to the increases in frequency. It does cut-off once the threshold for frequency error is crossed. But it does not throttle back for lower frequency increases.

A long period of troubleshooting with the suppliers and including Goodwe HQ has not produced results beyond establishing there is a problem and that a firmware fix is somewhere in the pipeline. They are not able to provide any information on when this may be.

In the meantime the Goodwe and it's array sit idle!

Would it be possible to implement the export limiting function in the Goodwe such that it will not export back in to AC-Out on the Quattros and only follow the loads on the distribution side? i.e. the CT clamp is positioned between the PV Inverter and the Quattros.

I understand that if this is not 'a very bad idea' for technical reasons then the Goodwe would not contribute to battery charging. This would be acceptable at least until a more robust solution is devised by Goodwe.

export-limiting-ac-coupled-inverter-on-ac-out.png

AC PV Coupling
export-limiting-ac-coupled-inverter-on-ac-out.png (196.5 KiB)
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Paul B avatar image Paul B commented ·

As a work around for you and you would need to double test this.

1. put the goodwe on AC2 out

2. then setup a assistant using general flag to open AC2 out if the voltage DC voltage rises above say 56 volts on your batteries for 1 sec, (set this to be around the bulk voltage setting you use

3. add another assistant that closes AC2 out when the DC voltage drops below say 54 volts , adjust as needed


This will then let you use the array until the goodwe is sorted to work with frequency shift.

it basically causes a grid failure to the goodwe and thus it turns off. but does not affect any loads on AC1 out


THIS IS a work around I have used sometimes when needed.


use at you own discretion, but make sure you are happy with the results and are happy that its safe to do so in your situation.


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rodgerd avatar image rodgerd Paul B commented ·

Hi Paul,

Thanks for the comment. I actually already have it setup like that and it is a viable work-around. Am hoping for something that offers a smoother transition or following of the load.

Trying the export limit option means sourcing the required energy meter for the Goodwe. I'm hoping for a sanity check on how this may work with the CT on the upstream side of the inverter before going to this expense.

Cheers,

R

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Paul B avatar image Paul B rodgerd commented ·

On the inverters I have used the setting for frequancy shift settings are all in the country code you select on the grid tie inverter try a diferant country code, may get you over the hump

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rodgerd avatar image rodgerd Paul B commented ·

Thanks - We did try that. In addition Goodwe support supposedly changed various parameters remotely. Unfortunately this is all opaque and not in the standard documentation so I don't really know what they did. At one point they did succeed in setting the value for Fac [the high limit frequency that causes the inverter to cutout] to above the maximum set in the Victrons. They did not inform me of this and did not pay attention to my increasingly frantic warnings that bad stuff was happening!

Their notional idea - not well thought out - was that somehow the Victron was not coming up to frequency. This despite having the actual frequency readout on the Goodwe showing the same values as on the Victron kit and as on an independant meter. At the time for that set of test the minimum production was supposed to be at 51.6Hz and cutout at 52Hz. At 51.6Hz power output was still rising. 10 minutes later when the battery tripped it was still rising!

Am not impressed!


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chrisfrgsn answered ·

@rodgerd Hi was there an update to this? I have an almost identical problem using a goodwe inverter as well and would be interested to see if there was a solution. Thankyou

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CM avatar image CM commented ·
Hello Chris, were you able to sort yours out ? Thank you
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