you can add a heat exchanger to the condenser water loop as a place holder. Then export the IDF from the OS file. Change the vrf type into water cooled in the idf editor and connect to the heat exchanger nodes. Then delete the heat exchanger from the idf.

Edit: as of 3.0.0, this is now supported (OSApp doesn't fully support it yet though). Cf OpenStudio#3613

[1] (main)>
    m = Model.new
    vrf = AirConditionerVariableRefrigerantFlow.new(m)
    p = PlantLoop.new(m)
[2] (main)> p.addDemandBranchForComponent(vrf)
=> true
[3] (main)> vrf.condenserType
=> "WaterCooled"

I just added OSApp support in OpenStudioApplication#185

Original answer:

Similar to this question which never got answered.

You can't use a Water-Cooled VRF in OpenStudio at the moment.

See the source code: AirConditionerVariableRefrigerantFlow.cpp#L1850. It doesn't have the AddToNode method, which is needed in order to be able to connect it to a plantLoop (see here for example)

I don't think there's a ton of (but definitely some) work to be done to be able to add this capability. The AddToNodemethod should be implemented, and then there's testing... But I haven't thought about it for long enough, so many there are complications I am not foreseeing.

As far as how to do that currently, I'd say model an AirCooled VRF, a plant loop, then use an EnergyPlus measure to tweak the object and connect them to the proper plant loop... You might need to use some hacks, such as making sure your plant loop is valid so that it's forward translated properly.