Add-PSSnapin microsoft.sharepoint.powershell
$WebAppName = "http://wtcsps99:82/"
$wa = get-SPWebApplication $WebAppName
$wa.UseClaimsAuthentication = $true
$wa.Update()
#admin account: yourDomain\yourUser
$account = "westrac\sp.admin"
$account = (New-SPClaimsPrincipal -identity $account -identitytype 1).ToEncodedString()
$wa = get-SPWebApplication $WebAppName
$zp = $wa.ZonePolicies("Default")
$p = $zp.Add($account,"PSPolicy")
$fc=$wa.PolicyRoles.GetSpecialRole("FullControl")
$p.PolicyRoleBindings.Add($fc)
$wa.Update()
$wa.MigrateUsers($true)
$wa.ProvisionGlobally()