I see no error checks in your code. Add some, see the Win32::OLE documentation for details.

I see neither use strict; nor use warnings;. Add them.

The VBA line looks like a single call to Protect, whereas your Perl code makes two different calls. Try rewriting it to a single call ...->Protect({Type=>wdAllowOnlyReading,Password=>$password});

By the way: "$var" is useless work most of the times, use $var instead.

Alexander