Editorial

Testing IEC 61850 Devices: What is Different?

It looks like the electric power industry is beginning a transition to the twenty first century by shifting from the hardwired protection, automation and control systems of the last century to the IEC 61850 communications based systems that are gaining acceptance by utilities all over the world.

This is the beginning of a new era, especially for the protection, automation and control industry. Considering how conservative some of the protection specialists are, it is especially important to convince them that the transition from the technology we know to a technology that may be difficult to understand is first of all worth it. Then second, but most important – that it works better than the technology we have today.

The only way to achieve that however, is not through nice Power Point presentations, but by demonstrating its quality. To demonstrate how well it works, by comparison with the conventional solutions. Thus, we come to the realization that we need testing.

These are some of the reasons to focus our attention in this issue of the magazine on the testing of IEC 61850 based devices and systems.

Like in any human activity, before we start, we need to ask some questions:

  • What do we need to do?
  • Why do we need to do it?
  • How do we do it?

As with any other question, we can start answering with "It depends.". If we think about what we need to do as part of the testing process, the answer depends on what we are testing. If we are testing an individual device with IEC 61850 GOOSE interface, the test procedure, equipment and tools requirements will be different from the case when we are testing a multifunctional IED with process bus interface. If we are testing distributed applications, protection schemes or the complete substation protection, automation and control system, we will need to consider the specifics of its function boundary, interfaces and behavior.

The second question also may have different answers that depend on the purpose of the test. Type and acceptance testing imposes very different requirements from commissioning and maintenance testing. The analysis of a protection misoperation will also lead to the use of a different set of testing tools. The answers to the first two questions are valid for any protection device or system and are easy to understand by any PAC specialist.

The last question is the one that is challenging to many and it is the one that we are trying to address in this issue of the magazine. And a good approach to do that is by starting with what we know and understand, and then looking at the differences with the new technology in front of us. When we think about testing any device or system, we know that we have two main components:

  • Test object - this is what we need to test
  • Test device or system - this is what we use to do the testing

The test object has different interfaces with its environment that support its functionality. The test system then needs to be able to replace the real world signals with the simulated ones, while at the same time monitor the behavior of the test object to determine if it passes the test or not.

Maybe you are now thinking "What is new here?". And this is good, because in principle when testing IEC 61850 devices and systems we do not have to change the concepts and methods that we have been using for hardwired IEDs or protection systems. The only difference is that we need to replace some of the wired signals with communications messages. Which exactly do we need to replace and how we do it depends on the test object:

If it is a simple IED with GOOSE interface – the test system needs to be able to publish and subscribe to GOOSE messages.

If it is a Merging Unit – the test system needs to be able to subscribe to the sampled values.

If it is an IED with process bus interface – the test system needs to be able to become a sampled values publisher.

The rest of it is details that you, as PAC specialists would love to dig in. And reading the articles in this issue will help you make the first steps.

Let?s start with organization in protection testing