Research On Communication Reliability And Real-time Performance Of Smart Substation Communication Network Based Oncobweb Topology

Smart substation is the key connection among power generation, transmission, transformation, distribution and management, and it provides the standardized and reliable support to the smart grid. As the “nervous system”, the communication system in smart substation directly determines stabilized operation of substation function. Considering the researches are all forces on the portability use of traditional standard Ethernet topologies, networking methods and communication protocols in smart substation, so the special performance requirements cannot be satisfied, and also, there will be no self-healing capacity under some special situations. Based on smart substation, and in the view of smart substation special performance, this paper was conducted to improve the performance of smart substation communication system and self-healing capacity under some special circumstances.This paper first analyzed the characters of LAN topologies, networking methods and communication protocols, and summarized the problems and shortcomings of those current techniques if they were used in the smart substation. Based on the special requirements of smart substation communication network, this paper proposed a novel smart substation communication network structure based on cobweb topology, it guarantees the communication reliability in the aspect of structure topology. From theoretical analysis and comparisons with traditional topologies, the smart substation communication network with cobweb topology was proved to have higher reliability and the mean time to failure is longer. With cost-efficiency theory, the cobweb topology was proved to have much higher values and application prospects.From the view of deterministic, the performance of cobweb based substation communication network was further analyzed in this paper. Combined with logical nodes networking method, the real-time performance of the novel topology was analyzed and compared with the traditional topologies deeply with network algorithm, in the aspect of message end-to-end delay bound. The analysis results showed that the real-time performance of the proposed topology is better than the others, and also, there will be much more communication paths satisfied the requirements of end-to-end message delay bound based on IEC 61850.Based on the extreme circumstance of worst-case situation that defined in IEC 61850, and with the proved communication performance of cobweb topology, this paper proposed an improved seamless data distribution based on MPLS, with the help of multi-path characteristic in cobweb topology. The simulation analysis was further conducted for verification. The simulation results showed that this improved distribution method effectively resolved the problems of high link utilization, non-convergence of message end-to-end delay and unsatisfied with IEC 61850, which are induced by extreme data surge. Simultaneously, this improved distribution method successful resolved the problems of the need of recovery time and messages lose, which are caused by using traditional communication protocols. Thus, this improved distribution method improved the self-healing capability of smart substation communication network when the data surge happed, and hence, guaranteed the stable operation for the smart substation network under different circumstances.