Rename XSL without save prompt using PowerShell - excel

Question

I am a novice to PowerShell and have been working on the following script to look through a directory for XLS and XLSX files. Afterwards, it would get the creation date of each file and rename the filename with the creation date appended to the end.
This script works fine for XLSX files. However when XLS files are encountered, the is save prompt: "Want to save your changes to xxx.xls?"
How can I get rid of this save prompt. Below is my code. Thank you:
Param(
$path = "C:\Excel",
[array]$include = #("*.xlsx","*.xls")
)
$application = New-Object -ComObject Excel.Application
$application.Visible = $false
$binding = "System.Reflection.BindingFlags" -as [type]
[ref]$SaveOption = "microsoft.office.interop.Excel.WdSaveOptions" -as [type]
## Get documents
$docs = Get-childitem -path $Path -Recurse -Include $include
foreach($doc in $docs)
{
try
{
## Get document properties:
$document = $application.Workbooks.Open($doc.fullname)
$BuiltinProperties = $document.BuiltInDocumentProperties
$pn = [System.__ComObject].invokemember("item",$binding::GetProperty,$null,$BuiltinProperties,"Creation Date")
$value = [System.__ComObject].invokemember("value",$binding::GetProperty,$null,$pn,$null)
## Clean up
$document.close([ref]$saveOption::wdDoNotSaveChanges)
[System.Runtime.InteropServices.Marshal]::ReleaseComObject($BuiltinProperties) | Out-Null
[System.Runtime.InteropServices.Marshal]::ReleaseComObject($document) | Out-Null
Remove-Variable -Name document, BuiltinProperties
## Rename document:
$date=$value.ToString('yyyyMMdd');
$strippedFileName = $doc.BaseName;
$extension = $doc.Extension;
#write-host $strippedFileName;
$newName = "$strippedFileName" +"_" + "$date"+ "$extension";
write-host $newName;
Rename-Item $doc $newName
}
catch
{
write-host "Rename failed."
$_
}
}
$application.quit()
$application.Workbooks.Close()
[System.Runtime.Interopservices.Marshal]::ReleaseComObject($application) | Out-Null

Answer 1

According to this old kb article, you can trick excel into not prompting you by setting the Saved property on the workbook to true, so I would try:
$document.Saved = $true
$document.close([ref]$saveOption::wdDoNotSaveChanges)