PowerShell V3 and PowerShell ISE V3 is not a port of Windows 7 and Windows Server 2008 R2. However, you can download it from here.
You might receive following error when you install the msu file
The update is not applicable to your computer
- Installed Windows 7 and Windows Server 2008 R2 Service Pack 1
- Install .NET 4.0 Full Profile. ( not client profile )