Prospect and key techniques of Global Energy Interconnection Zhangjiakou Innovation Demonstration Zone

In the Background of implementing innovation-driven development strategy and building Global Energy Interconnection, the necessity of building Global Energy Interconnection Zhangjiakou Innovation Demonstration Zone for stimulating economic growth, promoting social development and supporting 2022 Winter Olympics are discussed by analyzing the location advantages of Zhangjiakou and the characteristics of renewable energy in Zhangjiakou. Solutions are put forward in aspects of renewable energy integration in National Wind/Solar/Storage/Transmission Pilot Project, VSC-HVDC transmission of renewable energy and demonstration utilization of renewable energy in the Olympics zone, which could be a reference for problems of large-scale renewable energy in secure integration, outgoing transmission and flexible consumption. And replicable experience for building Global Energy Interconnection will be provided by conducting ±500 kV VSC-HVDC Power Grid Demonstration Project, Virtual Synchronous Generator Demonstration Project, Flexible Substation and AC/DC Power Distribution Network Demonstration Project, EV Battery Secondary Utilization Energy Storage Demonstration Project, Smart Grid Demonstration Project of Low Carbon Winter Olympics and other demonstration projects.

A Topology-Aware Relay Lookup Scheme for P2P VoIP System

Because of the best-effort service in Internet, direct routing path of Internet may not always meet the VoIP quality requirements. Thus, many researches proposed Peer-to-Peer VoIP systems such as SIP+P2P system, which uses relay node to relay RTP stream from the source node to the destination node and uses application-layer routing scheme to lookup the best relay nodes. The key of those systems is how to lookup the appropriate relay nodes, which we call relay lookup problem. This paper presents a novel peer relay lookup scheme based on SIP+P2P system. The main ideas are to organize the P2P network using a Cluster overlay and to use topology-aware to optimize relay selection. We introduce the mechanism in detail, and then evaluate this mechanism in NS2 network simulation environment. The results show that our scheme is scalable and can get high relay hit ratio, which confirm the feasibility of a real system. We also make comparison with traditional schemes and the results show that our scheme has good path quality.