if((Get-PSSnapin "Microsoft.SharePoint.PowerShell" ) -eq $null) { Add-PSSnapin "Microsoft.SharePoint.PowerShell"};

[System.Reflection.Assembly]::LoadWithPartialName("Microsoft.SharePoint")
[System.Reflection.Assembly]::LoadWithPartialName("Microsoft.Publishing")
[System.Reflection.Assembly]::LoadWithPartialName("System")
$site = new-object Microsoft.SharePoint.SPSite("https://mysite");
$web = $site.OpenWeb()
$fileDWP = $saveFolder + "myCustom.dwp"
$errorMsg = ""
[Microsoft.SharePoint.SPList]$wpList $site.GetCatalog([Microsoft.SharePoint.SPListTemplateType]::WebPartCatalog)
$fileStream = ([System.IO.FileInfo](Get-Item $fileDWP)).OpenRead()
[Microsoft.SharePoint.SPFolder]$wpFolder = $wpList.RootFolder
[Microsoft.SharePoint.SPFile]$wpFile = $wpFolder.Files.Add("myCustom.webpart", $fileStream, $true)
$wpFile.Update();
[System.Xml.XmlReader]$xmlReader = [System.Xml.XmlReader]::Create($wpFile.OpenBinaryStream())
[Microsoft.SharePoint.Publishing.PublishingWeb]$pubWeb = [Microsoft.SharePoint.Publishing.PublishingWeb]::GetPublishingWeb($web);
[Microsoft.SharePoint.SPFile]$defaultPage = $pubWeb.DefaultPage;
[Microsoft.SharePoint.WebPartPages.SPLimitedWebPartManager]$wpManager = $defaultPage.GetLimitedWebPartManager([System.Web.UI.WebControls.WebParts.PersonalizationScope]::Shared)
$myCustomWP = $wpManager.ImportWebPart($xmlReader,[ref]$errorMsg) $wpManager.AddWebPart($infoWp, "Right", 1); 
$fileSream.Close()
$xmlReader.Close()
$pubWeb.Close()
$web.Dispose()
$site.Dispose()
write-host "Done"