question

smart-home avatar image
smart-home asked

High grid voltage and throttling with Multiplus II in Australia

During peak solar times around the middle of the day, my MultiPlus II sometimes will disconnect from the grid in times of high voltage (as required), because it does not throttle back the power being exported (soon enough).

Powercor say my grid voltage is within specification, yet I find it usually is not possible to export 5kW to the grid without exceeding high voltage limits. (Maybe they keep the grid voltages high on purpose!)


To me, the problem lies with throttling back PV sources.....and I question whether it is the Grid code, V1-V4 values for Volt-Watt response curve that trigger the throttling?

1635941129786.png

My settings (pictured) do not match those that my distributor (Powercor) recommend, where they say V3=253 and V4=259.


In my case, I have a DC-coupled MPPT charger which does throttle back, albeit a little late....

Also I have an AC-coupled Fronius inverter which I was told before commissioning that it would be controlled via frequency shifting. This I believe cannot happen whilst connected to the grid and instead can only happen through a Modbus TCP connection. Throttling will work using Modbus, but again too late!

--> What settings will allow throttling to occur sooner?



Furthermore, when using Modbus the GX device shows the Fronius connection as (sunspec) and the Fronius status as "Running(Throttled),
versus not using Modbus it shows the Fronius connection as (solarapi) and the status as "Running".


When using Node-RED to retrieve data, sunspec & solarapi behave differently - with solarapi giving better information for Status and Error codes.

--> Can we use Modbus for throttling, and also use the solarapi connection?


Any help appreciated!

Multiplus-IIESSFroniusModbus TCPgrid
2 |3000

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

1 Answer
David avatar image
David answered ·

I am also interested in these settings. My grid voltage was high, and after an investigation, Ausgrid (NSW) retapped a bunch of transformers. One for my place and a few others in the streets around me as the voltages were all high - up to around 258 on a really bad day, but frequently over 255. After the retap I no longer had issues.

Ausgrid supplied the following details:

ausgridrecommendation.png

Based on this, I altered by Reactive power settings as per below:

victronvoltvar.png
I'm not sure if these are correct, or if they work.. But it is what mine is currently set to. Id be interested in knowing if I have correctly translated what Ausgrid have suggested into the correct victron settings.




2 |3000

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.