1. There is a Smart Tool Available in SAP ERP to extract - Contracts, Purchase Orders and Invoice. This tool is used to load data to SAP Spend Analytics. Data can be extracted in CSV format.
1239883 - Extractor Starter Kit for Spend Performance Management(SPM)
2. You can leverage this tool. Its an Add On available to every SAP customer @ Service Market place.
3. Ariba Integration Tool Kit will connect to SAP ERP. Ariba Tool Kit can be leveraged for seamless data transfer in CSV Format.