H IERARCHICAL C OMMUNICATIONS I NFRASTRUCTURE IN S MART G RID Xiaoxia Zhang

O UTLINE Cognitive Radio Based Hierarchical Communications Infrastructure for Smart Grid  Hierarchical communciation structure  Challenges on the design of communication architecture  Cognitive radio based architecture Reliable Overlay Topology Design for the Smart Microgrid Network  Microgrid  Smart microgrid  Overlay topology design for smart microgrid networks

Cognitive Radio Based Hierarchical Communications Infrastructure for Smart Grid

H IERARCHICAL S TRUCTURE

Home area network (HAN) - communicate with various smart devices to provide energy efficiency management and demand response Neighborhood area network (NAN) - connect multiple HANs to local access point Wide area network (WAN) - provide communication links between NANs and the utility systems to transfer information

C HALLENGES ON THE DESIGN OF COMMUNICATION ARCHITECTURE Tremendous data amount - explosive growth of data gathered by smart meters and sensors - utilities handle 10,780 Tbytes in 2010, 75,200 Tbytes in 2015 Energy sources - balance utility source and renewable energy sources Highly varying traffic - peak hour requires high data rate and more reliable services Interoperability - ensure operation among generation, transmission, distribution and user networks Quality of service - meter data needs higher priority and QoS, while price data needs normal priority and QoS Security - computer networks for controlling and monitoring, exposed to attacks

C OGNITIVE RADIO BASED ARCHITECTURE Motivations:  Increasingly intensive radio systems in HAN.  CR improves spectrum utilization and communication capacity to deal with large amount of data.  CR devices could manage context awareness to enable the realization of the heterogeneous network.

C OGNITIVE RADIO BASED ARCHITECTURE

C OGNITIVE RADIO BASED HAN HGW: cognitive home gateway used to transmit data and manage spectrum band. Two components: spectrum access controller and power coordinator.

C OGNITIVE RADIO BASED NAN NGW allocates spectrum bands to HGWs. Guard channel strategy: some reserved channels for handoff for both PUs and SUs to guarantee QoS. Pd: dropping prob. Pb: blocking prob. N G : guard channal N C : common channel

C OGNITIVE RADIO BASED WAN/NAN A WAN has K NANs.

Reliable Overlay Topology Design for the Smart Microgrid Network

M ICROGRID Small-scale, self-contained medium/low power system. Distributed generators (DG), controllable loads, small-scale combined heat and power units (CHP) and distributed storage (DS). Two operation modes: grid-conected and islanded.

S MART M ICROGRID Less transmission loss and less cable loss Reduce carbon emission Fault isolation in case of a failure or attack Ease of DG handling Energy trading among microgrids (future) SMGs can form a network SMGN to maximize the utilization of renewable energy resources.

O VERLAY TOPOLOGY DESIGN FOR SMGN Target  survivability (stay in working condition in case of a failure)  utilization of the renewable resources more effectively Method  Form clusters in a SMGN

O VERLAY TOPOLOGY DESIGN FOR SMGN Step1: Cluster SMGs. SMGN: G(t)={V,E(t)} where V is the set of SMG and E(t) is set of logical links among SMGs. |V|=N. Link between two SMGs (u,v)€E(t) means u and v can share the storage bank. is binary, 1 if and only if SMG i and SMG j are on the same cluster. Survivability for Cluster r

O VERLAY TOPOLOGY DESIGN FOR SMGN Step2: Find a Hamiltonian cycle in each cluster.

S IMULATION RESULT

Questions and Discussion? Thank you! 19