Re: How to get a providervdc from organization name or org reference?

You need a VDC as a starting point (you can get the VDCs from an org but these can have different provider VDCs).

var host = vdc.getHost();
var providerVdcReference = vdc.toAdminObject().providerVdcReference;
var providerVdc = host.getEntityByReference(VclFinderType.PROVIDER_VDC, providerVdcReference);