Let’s talk about IEC 61850

Interview of Sjoerd Bearda

Grid Project Engineer at Swissgrid AG


Sjoerd, have you been involved recently in a project using the IEC 61850-9-2LE standard?
“Besides the newly installed OCT’s in the substation of Châtelard, we were not recently involved in any other project using IEC61850-9-2LE.”

What have you learnt from using IEC61850-9-2LE?
“For Swissgrid as an end user, we cannot comment on the subject of the IEC918650-9-2 protocol as we have only a few first experiences in this project during the commissioning. For Swissgrid the main difference is, instead of using a conventional CT circuit, a data stream is used. We expect more learnings in using this data stream during the operation phase of this monitoring system.”

What was your experience interacting with the OCT supplier?
“We were very satisfied with the supplier CONDIS for the OCT’s, especially for the obliging way to meet the specifications and deadlines.”

Do you see during coming month/years other projects where OCTs could be needed?
“At the moment we do not see any need for further OCT’s. We would like to gain more experience in this technology. Swissgrid is very careful with new systems, especially when it comes to protection systems. Swissgrid must be able to rely on protection systems that have proven themselves over many years.”

What application do you see as most promising for the use of OCTs?
“For measuring currents with long-lasting DC component, we will go again for an OCT solution and for remote measurements with a long distance to the protection relay.”

Based on your experience, what should customers be aware of when planning the transition to digitized substation?
“The transition to the digital substation has advantages and disadvantages. With the entirely numerical solution, these are self-monitored and therefore regular checks of the CT measuring circuits are not necessary. A major disadvantage is still the uncertainty of the service life on the devices such as the OCT, measuring unit and the merging unit. Compare to the life span of 40 years and more on conventional CT’s. The industry does not have any long-time experience on the OCT technology.”

According to you, what are the most challenging aspects of the digitization of the grid?
“With competent suppliers, system integrators and reliable interoperable Products, as we have now experienced with CONDIS in the project Châtelard, we see advantages and opportunities in realizing digital substations.”

On the other side, what are its main opportunities?
“The main advantages we see today are the costs, the less erection works and a faster commissioning. Also, there is no danger anymore that the CT will be damaged if there is a fault on the measuring side. Last but not least less copper wires.”


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