IEC 61850 GOOSE Communication
What is GOOSE Messaging?
GOOSE (IEC 61850)
The GOOSE (Generic Object Oriented Substation Event) protocol is a communication model defined by the IEC 61850 standard, which uses fast and reliable mechanisms to group any format of data (status, value) into a data set and transmit it across communication networks within 4 milliseconds.
It is most commonly used for data exchanges between IEDs (IED – Intelligent Electronic Device) in electrical substations over Ethernet.
It provides these advanced communication features by applying the following mechanisms:
- GOOSE uses VLAN and priority tagging techniques defined in IEEE 802.1Q to divide one physical network into several virtual network and set the desired message priority level.
- GOOSE data is directly embedded into Ethernet data packets
- It works through a publisher-subscriber mechanism on multicast or broadcast MAC addresses.
- Enhanced retransmission technology — The same GOOSE message is retransmitted with growing, varying re-transmission intervals. When a new event occurs within any GOOSE dataset element, it will stop the existing GOOSE retransmission message. A state number contained in the GOOSE protocol identifies whether a GOOSE message is new message or has been retransmitted.
- GOOSE messages are based on the requirements of the IEC 61850 standard, which aims to provide vendor-independence. When using technologies and devices with a full support of IEC 61850, this enables truly interoperable substation networks without vendor specific requirements around equipment, configuration tools, cables, protocol modifications and algorithms.
Advantages of Using GOOSE
- Flexibility, adaptability and efficiency from relying on software configuration rather than hardwired signal paths
- Extremely high messaging speeds
- Increased reliability from inherent GOOSE data integrity checks
- Network can be freely extended and re-configured at low cost
How it Works
The general concept of GOOSE communication is that the publisher periodically sends messages and when an event happens (e.g. tripping signal, circuit breaker closing), it sends a burst of messages with new data.
GOOSE messages are event- and dataset based. While the type of dataset is not pre-defined by IEC 61850, it should contain fairly small numbers of status values and their quality. When a value of any dataset member changes, it triggers a change of “state” and the new information is instantly published.
Because the protocol is based on a publisher/subscriber mechanism, there is no confirmation that the sent message is correctly received by the subscriber, the message is retransmitted to prevent the loss of packets and inform newly connected devices of the current state. In order to preserve bandwidth, the delays between retransmissions grow over time from mininum threshhold immediately after the state change to the maximum time once the steady state condition is reached.
The subscriber receives all messages from the system, but only filters and parses the messages carrying the topic it has subscribed to.
What Can You Do with IEC 61850 GOOSE?
Peer-to-peer GOOSE communication can be used over an Ethernet-based substation network (replacing hard-wired blocking signal paths between switchgears) to enable sophisticated logic schemes for substation protection and automation.
Some of the most widely known and accepted examples are interlocking busbar protection schemes, circuit breaker failure protection, power quality controls of parallel power transformers and selective arc fault protection.
Interlocking schemes are particularly popular as they take advantage of the increased speed and security provided by GOOSE messaging, in addition to being a traditionally simple and efficient method to protect busbars in distribution substations.
What is IEC 61850?
The IEC 61850 standard was a response to the growing need for higher and deeper levels of control and automation in electrical grids. With steadily increasing numbers of devices, device types and data points, further accelerated by digitization, as well as the integration of new, often geographically distributed and heteregenous, generation sources, it became evident that future demands could not be met with the technological limits of serial protocols like Modbus.
In order to guarantee interoperability in the face of rapid technological development and product innovation in the industry, the IEC 61850 standard not only defines various communication protocols and interfaces, but also provides specifications concerning the substation modelling, configuration language and data models. For this reason, IEC 61850 is commonly referred to as “not just a protocol” and often called a data model or framework instead.
The scope of the standard allows to map the standardized data models and services onto serveral communication protocols and thus transfer the data via Ethernet using different protocols for different requirements and applications, as for example TCP/IP-based protocols for clients/server communications. For this reason, despite its initial focus on substation automation, the flexibility of IEC 61850 has spread its use to other applications, such as the integration of distributed energy resources (DERs) into the power system or the communication between intelligent devices in Building Management Systems (BMS).
The IEC 61850 standard distinguishes itself through the following elements:
Abstract Communication Service Interface (ACSI)
The ACSI (defined in IEC 61850–7‑2) describes the functions and services for the interaction between IEDs in the system. Examples of IEC 61850 services include the transmission of files, reading of data or assignition of values. The ACSI can be mapped onto various protocols, including MMS or web services.
System Design and Structure
The functions of the IEC 61850 standard are the often-heard logical nodes, which can simply contain device descriptions but usually represent a real physical device like switches, sensors or IEDs, and its entire range of functionalies.
IEC 61850 Protocol Suite
The IEC 61850 standard defines several different protocols for different purposes in substations and other facilities/ utilities.
The standard defines the low-level (process bus) client/server based GOOSE/GSSE (Generic Object Oriented Substation Events) protocol to transmit event data across networks at very high speeds. This enables to new possibilities for advanced substation automation and protection functions and schemes.
It also defines the more complex MMS (manufacturing message specification) protocol for communications between servers and clients. It provides a set of functions that allows the client to obtain the data model of the server, read or modify individual values, or even delete entries as well as to transfer files.
The last two protocols displayed on the chart comprise the Sampled Values (SV) protocol for the transmission of digitized instantaneous values of power system quantities, mainly primary currents and voltages and time synchronization protocols such as SNTP over UDP/IP.
IEC 61850 Protocol Suite
Interlocking Protection Schemes with GOOSE
How does interlocking work?
When a fault occurs on the busbar, the interconnected relays quickly coordinate, causing the relays of the incoming feeders to block the relays of the outgoing feeders and then trip the CB of the incoming feeder. The same happens vice versa when a fault arises on an outgoing feeder and the relays of the incoming feeder are prohibited to act.
Maximum Speed with the GOOSE Protocol
Since GOOSE messages are sent relay-to-relay, through an Ethernet LAN and thus there is no additional delay from intermediary equipment such as input filters or auxiliary relays. The blocking signals can be sent faster than in traditional, hardwired interlocking schemes. Peer-to-peer communication allows to send blocking signals to all relays at once, making the total operating time independent from network size, complexity or topology.
Higher Reliability and Adaptability
In addition to the native security features of interlocking schemes, the operational reliability can be further enhanced by the inherent supervision of GOOSE messages. When a blocking circuit is broken, unnecessary tripping is avoided as the blocking is not being issued. Instead of rendering the protection inoperative in such a case, GOOSE’ inherent supervision generates an alert to initiate the maintenance/repair process and react as quickly as possible.
This supervision function can also be utilised to adapt to application requirements. Depending on the object to be protected, one function must often be prioritzed over another. For instance, it may be necessary to sacrifice some operation speed in order to achieve selectivity or vice versa. Such adjustments can be easily made to the configuration of the GOOSE service in order to obtain the best protection possible.
Unique Speed with GOOSE Supporting Remote I/Os (RIOs)
With the ultra-fast processing time (P2/P3) of iRTUe remote I/O extension units you can take full advantage of a fast network based on IEC 61850 GOOSE. It enables direct and fast communication with relays and master units (e.g. iGW & iRTU families) and the integration of analog and digital power quality measures at ultra-high speeds.
The (P2/P3) performance class is the highest performance class of the IEC 61850 standard, demanding a total transmission time below the order of a quarter of a cycle. Therefore setting the limit to 3ms. The folIowing graph demonstrates how the transmission time is defined in IEC 61850–5:
The trip is the most important fast message in a substation network and for this reason the speed performance requirements are particularly high. However, such speeds can also be necessary (or at least beneficial) for other operations including interlocking, intertrips and logic discrimination between protection functions.
State-of-the-Art GOOSE Projects
This speed is already being demonstrated and put to use in the advanced protection system SPS by our partner HCE from Taiwan. The system uses the iRTUe as GOOSE to Digital Output converter for quick trips in load shedding schemes and as an IED I/O expansion module to provide full flexibility. The system also takes advantage of the high capacities of the iGW-VM software, which acts as central IEC 61850 hub, collecting data from all devices within the network.
Using iGrid T&D for such applications provides many advantages beyond the protocol itself, such as:
- Particularly fast processing time of iRTUe extension units
- IEC 61850 protection relays by Italian market leader Thytronic (group company)
- Full IEC 61850 support throughout all network devices (protections, I/Os, gateway servers, masters, SCADA etc.)
- IEC 61850 GOOSE and MMS communication
- Many years of in-field experience in a diverse range of applications
Any questions about this?
The GOOSE (Generic Object Oriented Substation Event) protocol is a communication model defined by the IEC 61850 standard, which uses fast and reliable mechanisms to group any format of data (status, value) into a data set and transmit it through electrical networks within a time period of 4 milliseconds.
It is most commonly used for data exchanges between IEDs (IED – Intelligent Electronic Device) in electrical substations over Ethernet.
IEC 61850 MMS (Manufacturing Message Specification) is a client/server based protocol for communications between IEDs (IED – Intelligent Electronic Device) and higher level entities (such as RTUs and SCADAs) over Ethernet that is part of the IEC 61850 standard for communication technology in substations.
It is mapped onto TCP/IP and allows to access the server through its IP address in order to write/read data and exchange files.
The IEC 61850 standard for substation automation specifies a standardized Substation Configuration Language (SCL) to transfer device descriptions and communication parameters amongst different vendors/ manufacturers.
SCL files define several capability subsets for the IED to instantiate its capabilities.
The IED Capability Description (ICD) file is a specific type of SCL file, which are the configuration files defined by the IEC 61850 standard for modern substation automation.
It is usually supplied by manufacturers and defines the full capability range of an IED.
Logical nodes (abstract data objects) are the main elements of the virtual object-oriented IEC 61850 model, which consists of standardized data and data attributes.
They can represent switches in the grid, sensors, communication interfaces, or simply contain descriptions of devices.
all entries sorted aplhabetically
GOOSE Messaging & iGrid
iGrid T&D has a special commitement to interoperability and IEC 61850 in particular. For this reason, iGrid has developed a special tool “iConfICD” to configure IEC 61850 RTUs, SCADAs, I/O Extension units and other devices for IEC 61850 projects.
All iGrid devices and software solutions support GOOSE communication.
iConfICD is a state-of-the-art ICD design tool for the creation of ICD and CID files and the configuration and modelling of IEC 61850 servers.
The tool can be used to set up any device supporting IEC 61850 communication. It allows to create all of the standard’s Logical Devices and Logical Nodes, as well as to select the corresponding Data Objects, while strictly following the guidelines of the IEC 61850 edition 2 standard. With the integrated iEdit tool, expert professionals can also manually access and modify SCL files without restrictions.
The freely scalable iGW-VM supports all architectures using Windows or Linux, acting as a substation gateway, bay controller, RTU or communication front-end for SCADA systems. The iGW-VM is thus the perfect software choice for projects with a predetermined/preferred hardware or a large grid to cover (high number of datapoints).
iRTUe – Remote I/O Extensions
iGWs, iRTUs and third party master units can be freely extended by connecting one or several iRTUe.
They support IEC 61850 (GOOSE) communication and come in many configurations such as 48 DI, 16 relays, 16 AI, 24 DI + 8 relays, 24 DI + 8 AI or 8 relays + 8 AI.
iRTU – With I/Os for Direct Data Acquisition
Compact and scalable bay controller which can act as IEC 61850 client or server, featuring configurable I/O boards for direct data acquisition, high-precision timestamping and an optional Ethernet switch for additional Ethernet ports.
iGW‑S Substation Gateway
Powerful and reliable substation gateway, able to run either in standalone or redundant modes, with an embedded Ethernet switch (4 ports) and IEC 61850 client and server capabilities.
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