In this paper, we propose four new key management schemes for Advanced Metering Infrastructure (AMI) to secure data communications in the Smart Grid (SG). The schemes are based on individual and batch rekeying operations using a novel multi-group key graph structure, are also versatile in the sense that they can support broadcast, unicast, as well as multicast communications. Security analysis shows that our schemes satisfy key management security properties. Furthermore, performance analysis and simulation results demonstrate that our schemes can scale to large AMI systems, and they incur low cost in terms of storage, communication overheads and time of key distribution compared to state-of-the-art schemes.