Did you check these already?

http://communities.vmware.com/message/1475219#1475219

http://communities.vmware.com/message/1173158#1173158

Hello,

thanks for the reply.

I know the command for changing the portgroup name.

But i hope that there is any posibility to replace the "pubic" to "public" (i think there must be a way with "foreachobject").

Try something like this

$dvSw = Get-VirtualSwitch -Name MydvSw
$spec = New-Object VMware.Vim.DVPortgroupConfigSpec 
Get-View $dvSw.ExtensionData.Portgroup | %{
    if($_.Name -like "*-pubic"){
        $spec.Name = $_.Name -replace 'pubic','public'
        $spec.configVersion = $_.Config.ConfigVersion
        $_.ReconfigureDVPortgroup($spec)
    }
}

Or if you want to do this for all your dvSwitches, you could do

$spec = New-Object VMware.Vim.DVPortgroupConfigSpec
Get-VirtualSwitch | %{
    Get-View $_.ExtensionData.Portgroup | %{
        if($_.Name -like "*-pubic"){
            $spec.Name = $_.Name -replace 'pubic','public'
            $spec.configVersion = $_.Config.ConfigVersion
            $_.ReconfigureDVPortgroup($spec)
        }
    }
}