A Methodology to Implement and Investigate Performance of Sampled Values for Wide-Area Protection

© 2018 IEEE. IEC 61850 has been widely introduced into substations with the intention of reducing the complexity of hard-wired connections and implementing ethernet communications in protection and control applications. This standard is primarily designed to work within a substation and provide reliable communication framework between substation control room to all connected bay level and process level equipment. With the introduction of technical reports IEC 61850-90-1 and IEC 61850-90-5, it is now possible to implement IEC 61850 in wide-area. This paper presents a methodology to transmit and receive process level measurements known as sampled values (Instantaneous voltage and current measurements with time-stamp) between two substations on different Ethernet networks. This is achieved by using a unique Virtual Local Area Network (VLAN) ID that is assigned to the data packets and a Layer 3 switch that allows these particular packets into the network. This paper presents the laboratory setup to route sampled values between two different networks with the help of Opal-RT simulator, Layer 2 and 3 switches and communication network emulator. The main objective of this laboratory setup is to investigate the performance of sampled value data in a wide-area network with the influence of delays caused by transmission, background traffic, physical distance between the substations and unintentional delays due to communication devices. In addition, this work also evaluates the communication performance effects on phasor estimation, which will be used extensively in protection and control applications

An IP multicast framework for routable sample value communication in transmission grids

The growth and deployment of digital substations based on IEC 61850 in power utility industry will spawn new opportunities for wide area systems. These include monitoring, protection and control applications that will require suitable communication architectures and technologies. Techniques such as bridging and tunneling have been recommended for encapsulating and de-encapsulating messages between substations. These methods are however point-to-point solutions and are not suitable for wide area applications, involving multiple substations at the same time. In this paper, we propose using Protocol Independent Multicast- Source Specific Multicast (PIM-SSM), an IP multicast routing protocol for routable Sampled Value transmission in decentralized wide area systems. IP multicast is a technology tailored for one-to-many and many-to-many communications, such as wide area protection applications requiring multiple substations receiving R-SV messages in a single transmission from another substation in the power grid. We first show how PIM-SSM can be realized in a transmission grid communication network and present a qualitative analysis of effects on multicast when link failures occur. We then present a quantitative study to evaluate the performance of PIM-SSM, on selected communication network topologies. Our results show that the communication technology will play a critical role in efficient delivery of routable Sampled Value data in a multicast framework. Furthermore, they show that improvements in the networking infrastructure design leads to better performance of the multicast delivery