Introduction of new Information and Communication Technologies (ICT) and aggregation of equipment bring in new perspectives in terms of the increasing number of data users. It also brings new data delivery requirements which are difficult to be met by the legacy systems. Off-the-shelf standards and communication technologies are the enablers to push current data delivery solutions to a new level. At this level this new data delivery system can fulfill Quality of Service (QoS) requirements of next generation power system. This paper proposes a comprehensive architecture of Peer-to-Peer (P2P) based overlay-control data delivery system covering all levels of data delivery. The core technology of such an architecture lays on the Intelligent Substation Gateway (ISG), which is employed to provide data delivery service to meet the QoS requirements. Proposed data delivery system brings advantages as autonomy, flexibility, scalability, and efficient to the power system.