IEC 61850 - A BRAND NEW WORLD

Authors:
Christoph Bruner, UTInnovation, Switzerland
Kay Clinard, UCA International Users Group, USA
Alexander Apostolov, OMICRON electronics, USA

INTRODUCTION

IEC 61850 is an approved international standard for communications in substations that is creating opportunities for a revolution in the world of electric power systems protection and control. It represents the next step in integration of multifunctional IEDs based on the development and implementation of advanced distributed protection and control functions. But for this revolution to succeed, we need to understand what it is and how we can use it in order to take full advantage of its potential. That is why IEC 61850 and its applications are and will be one of the key topics for discussions in our industry in the future.

 

When we plunge into the IEC 61850, we enter a world of numerous MLAs. Probably you never heard of MLAs - well this is nothing but a Multi-Letter Acronym. And you are going to see TLAs and FLAs (you have to figure these out). Coming up with these was one of the primary tasks in the development of the standard (actually this is a joke).


The reason we are starting by talking about acronyms is because their use can be very dangerous. If we look at a very typical use case - you need to take a new relay to a remote substation. So you put it in your carry-on bag and you go to the airport, check-in and get in line to go through security. Almost every time, someone will ask you what is this thing in your bag. The natural to a protection engineer answer will be to say that it is an IED (we all know that in our domain this means Intelligent Electronic Device). Well, in our use case situation this is definitely the wrong answer, since in the world of security the same three letter acronym (or TLA) means Improvised Explosive Device. So the moral of this story is - be careful and use an MLA only within the domain that you understand.


We hope that you are starting to realize that the standard was developed by some "out-of-the-box" individuals that were trying to transform the world of hard wired electromechanical relays into a world of virtual devices communicating over substation local area networks. When this all started many were saying that this is impossible. They were wrong. We just need to look around to see where the world is going.


So let's try to get more serious and see why and how we got to where we are and where we are going. IEDs are the standard in new or upgraded integrated substation protection, monitoring and control systems. Protective IEDs are sophisticated multifunctional devices designed to protect substation equipment and the electric power system from the effects of different abnormal system conditions. Since fault conditions are very rare in the system, to take advantage of their data acquisition and processing capabilities they also include multiple non-protection functions like metering, disturbance and event recording and some built in fault analysis tools. This makes them the typical device at the process level of a substation automation system.


Specialized control, power quality monitoring and disturbance recording devices may complement the protection IEDs by providing some specific functionality that may not be available within the relays. This allows the optimization of the integrated substation automation system, while at the same time meets the strict requirements for reliability and security.
The selection of the communications protocol used at the substation level is one of the critical factors to consider in the design of the substation automation system. The protocol should provide all required services that will allow the optimal implementation of different substation functions. This requires:

  • Proper definition of the functional and performance requirements
  • Good understanding of the substation communications protocol

That is why we need to discuss IEC 61850 and its applications, as well as the challenges, benefits and opportunities for future developments.

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