One of the requirement I had was to download a certain file from the sharepoint on a daily basis and take a snapshot of the same for future reference. The drawback with Sharepoint is that we can download the file, but unless someone opens the file , refreshes all the connections and should perform the save, only then it will be updated. I achieved this with powershell and another tool available here – ExcelRefresh. You can use the code below to do that activity.
My setup was to place the ExcelRefresh.exe in the same folder where the downloads were being dumped.