Business Scheduling Technology Research And Simulation Based On IEC61850 Substation Communication Network

The substation automation communication system based on IEC61850is a link for connecting various kind of smart electric devices, is the lifeline of digital substation automation system. Since the communication network is mainly implemented for the real time data exchange among the nodes as well as other system, building a real time, reliability and high available communication network is the key to implement substation automation system. The switched Ethernet could realize the connection and communication between all of the devices to achieve all applications shared the network. A variety of applications data transferred and the real time transmission of the protection and control application on a shared network need an efficient QoS policy.Firstly, on the basis of introducing the network layer, information,model, communication map, and the information exchange process between IEDs in IEC61850substation, we abstract the P&C application model fromintroduce the simulation principle of OPNET Modeler in details and several kind of application modeling method. According to the client-server mode, the gna_procontrol_mgr module, standard application model of P&C application, is modeled on OPNET process domain. In the meantime, the theoretical analysis about the self-similar characteristic of the busty traffics in network is shown, the related RPG model and the IED modeling method on OPNET node domain are introduced. Then, the P&C application model and the IED model are simulated on OPNET; the result validated the accuracy of the new model.Secondly, to support the diversity of application and real time performance, we focus on the bandwith demand when the traffic for the most critical applications of teleprotection and synchrophasor class A measurements are mapped to the strict priority queue (SPQ) along with enterprise VoIP bearer traffic. Three different approaches about teleprotection Packet at the end (Tail) of the SPQ, at the front (Head) of the SPQ and preemption of packet under transmission, are considered. We focus on teleprotection traffics since it has the most stringent QoS requirements.In the end, based on the QoS congestion avoidance mechanisms RED algorithm, to adapt to the characteristic include high latency requirement and strong burst, we proposed an improved method WRED_gentle which could avoid discard packets rapidly in congestion and reduce delay by improving tolerance to network burst traffics. The WRED_gentle could improve the security and reliability of P&C application and smart meter-reding application. By applying such improvements in WRED algorithm in OPNET simulation, we prove that this method can improve network throughput and reduce packet loss rate.