With PowerCLI for vCD and vCenter it is particularily easy to determine the underlying vCenter resource pool for any vCloud Organization VDC. You first retrieve the resource pool relation via the Search-Cloud CmdLet via the urn of the VDC and then use the Get-ResourcePool CmdLet to get the actual resource pool (via Typed Queries):

$resPool = Search-Cloud -QueryType OrgVdcResourcePoolRelation -Filter "vdc==$($Ovdc.id)";
$resPoolVc = Get-ResourcePool -id "ResourcePool-$($resPool.ResourcePoolMoref)";

done.