A new kind of GOOSE
by Alex Apostolov, Editor-in-Chief
Many of us have seen flocks of geese in the sky on their way South or North depending on the season. We know that they cover huge distances, so it is not surprising that the original GOOSE that was intended only for substation applications got out in the wide open of the electric power grids.
We have been talking about GOOSE for almost 30 years and initially we used it over Layer 2 in the substation for high-speed peer to peer protection applications. One of the reasons that we liked it is that it allows devices from different manufacturers to operate and work together in different protection and control schemes.
With more and more applications in service and the satisfactory results of its performance and reliability many people started asking the question why we should keep it only in the substation, why not let it out to fly between substations or from one end of the power system to another when there is a wide area disturbance.
Many experts started looking at ways of using it based on methods such as tunneling to send it from a device in one substation to a device in another. And this was working and providing solutions especially between devices from different suppliers that could not talk to each other in the past. The challenge with such solutions was that they required a communications channel or a predefined path through the wide area network, which might be challenging in some cases.
That is why the members of IEC TC 57 working group 10 used as a stimulus the development of IEC 61850 -90-5 to define the use of routable communications for the transmission of sampled values and GOOSE messages.
In the meantime, the communications technologies continued to develop and in the last several years the speed of the Internet communications, as well as the use of mobile cellular networks for purposes other than phone calls became widely available.
While the Layer 2 communications in the substation have been considered secure because they didn’t have access to routers that was not the case for what became known as R- GOOSE.
Since it travels through the wild world of the Internet, we can imagine that it can become exposed to the attacks of many different actors with bad intentions that may result in local or wide area disturbances. That is why taking critical cyber security measures to protect the GOOSE communications became an important task that is being covered by the IEC 62351 standard and is addressed in one of the articles in this issue of the magazine.
At the same time another concern is that since the messages are going through an unknown path it is not clear how long it will take for the message from the publisher to reach the subscriber. This is why it is critical that the solutions based on R- GOOSE are subject to proper testing in realistic conditions and also require measurement and analysis of the latency of these communications.
Taking all of these into consideration, many utilities around the world have been using these messages for many transmission line protection applications and also going all the way down to the distribution level where the use of cellular networks allows it to be used for distribution automation or different communications-based protection schemes. Different use cases and methods for the implementation of such technologies are described in several of the articles in this issue of the magazine.
Another challenge is the fact that not all manufacturers are supporting R- GOOSE messages and this is why an alternative to their direct publishing from an IED at least at the initial stages can be done through a gateway that will convert the Layer 2 GOOSE message into a routable message. This may have an impact on the latency of the message, but such delay will still be much less in comparison to using the time delayed protection scheme. This is why it is essential to have a clear understanding of the performance requirements for each specific application and make sure during the engineering and testing of the protection schemes that they meet these requirements while using the wide area communications.
R- GOOSE is a very exciting development for our industry because it opens it to extensive use of communications-based protection schemes that are going to improve significantly their performance and efficiency without significant increases in their costs.
“Efficiency is doing better what is already being done”