Here is a starter that can extract all the time values:
$regex = 'TestCase_'
foreach($line in Get-Content -Path $mylog)
if($line -match $regex)
$test, $success, $time = $line.Split()
$time = $time.TrimEnd('s')
I have not used Excel from Powershell so am not sure what to do with the time fields. You could take a look at Introducing the PowerShell Excel Module - Scripting Blog
], which is a very useful website.