Add list of users to SharePoint group using powershell

After migrating SharePoint 2010 site to SharePoint 2013 the user permission is not working as in 2010. The users are getting access denied message. This is due to SharePoint 2013 use the claim based authentication mechanism. As a quick fix I wrote a power shell script to add users to a SharePoint group.

Store the users in a text file as bellow format:

i:0#.w|domain\username

Use the bellow script to add permission:

 $loc = Get-Location;  
 $Users = Get-Content "$loc\Users\Users.txt";      
 foreach ($User in $Users) {       
 write-host($User);  
 Set-SPUser -Identity $User -Web "http://shpapp:2000/sites/TaskApproval/" -Group " Task Confirmation Users";       
 }