Experience in Communication Network Design for High Performance Requirements in IEC 61850 Process Bus based Substation Praveen A.N.1, Girish M.V.1 1ABB Power Products and Systems India Limited Online Published on 12 May, 2022. Abstract A process bus-based substation (henceforth referred to as digital substation) has two main interface levels viz: one between the process level devices and Protection and Control IEDs (PCI) and the other one between PCI and station level devices. Both interface level exchange information based on communication services defined in IEC 61850 without any hardwired connection. A process bus is formed by connecting all the process interface devices and is an interface between process level devices and PCI. A station bus provides an interface for exchanging the information between bay level and station level devices for monitoring and control applications. While the network traffic in a station bus is dominated by GOOSE, process bus network traffic is dominated by Sampled Values (SV). The operational and protection philosophies of utilities have not changed for a digital substation. The behaviour and performance of PCI both in conventional substation and a digital substation have thus remained same. Hence, KPI for evaluating the performance of a digital substation PCI remain same as that for a conventional substation. The KPI are Speed, Sensitivity, Security and Reliability. The Design of communication network for both station bus and process bus must be such that all KPI are satisfied. Communication Latency and Communication Redundancy based on IEC 62439-3 are the two additional parameters that further influence KPI in a digital substation. The paper elaborates the experience in designing communication network for Protection and Control Systems (PCACS) of a digital substation with three voltage levels and 22 bays having approximately 74 IEDs, 56 SAMUs and 45 SCUs. The paper starts by describing the design philosophy in selecting the apt number of MUs for an optimal SV traffic on communication network and ideal performance of PCIs in a digital substation. Use of data segregation between station bus and process bus, use of VLANs and MAC address filtering-based network traffic control methods are then explained to achieve the objective of seamless, fast and reliable operation of PCIs. Based on the design philosophy adapted, performance of PCI in a digital substation under conditions such as breaker failure operation followed by trip from bus bar protection IED, auto-reclose operation following an EHV line fault is discussed. Top Keywords Digital Substation, Sampled Values, GOOSE, Network Traffic Control, VLAN, MAC address filtering, Intelligent Electronic Device (IED). Top |