question

I cant comment on speciffoc victron kit, if it even exists, but I have grid connected many generators on Hydro systems that are either an odd frequency or have to change their frequency to match water conditions...

It seems to me that simple is better. Rectify whatever you have so frequency is off the table and then charge from the DC.
There is probably a product for that and if the voltage is way off whatever the chosen charger will handle a basic transformer will bring that into the ballpark before you rectify it.

I know Victron produce kit that would 'probably' do the job but I am not an expert and dont want to give you an example, or even a possibility, as I could well be suggesting kit be used inapropriatly or just talking nonesense.

For the hydro, all be it 3 phase on the grid side, I use 30kW inverters designed for wind turbine use.

I dont even use an AVR on the generator... The voltage is proportional to RPM, all be it at a selectable level, and the inverter has a steep export curve.

If the prime mover speeds up the voltage increeses slightly so the export go's up which adds load and things ballance out again.

The net result ia a relativly small voltage operating window and the ability to set the desired turbine speed by changing the excitation.

I realse that your requirement is different but I woulsd be inclined to suggest that the methodology is probably a good starting point.

Somone more aware of Victron specs may be in a position to suggest a product that will take DC, with a bit of ripple, and make stable AC to feed your chargers... All you would have to do then is set under frequency rolloff on the grnerator and manage charge current based on the rectified voltage.

Victron have products that do that, DC to AC whilst managing power. but as I said I can't comment on weather thay will handle rectified AC as opposed to DC on their input so cant actually suggest anything speciffic.

Sorry,

Al