Intelligent switchgear needs an integral test approach

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Intelligent switchgear needs an integral test approach
The latest grid components are more and more required to have real-time controllability to be directly able to respond to rapidly changing grid conditions. Intelligent electronic devices (IEDs) are the gateways that communicate through ‘big data’ to the outside world.
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  • Keywords: KEMA Laboratories, Manufacturers, Utilities

Digitalization of equipment therefore is the drive to protection, telecontrol, monitoring, metering, automatic grid restoration etc. and the data must be trusted. Transformers, circuit breakers and even cables will feature embedded sensors that are in constant communication with the network operations center. In other words, grids will join the celebrated Internet of Things – and in a big way. From KEMA Laboratory’s experience, electronic components with IED functionality, have a failure rate up to 80% in a test environment. Whist there are already standards for electromagnetic compatibility, many in the power industry question how well these apply given the abnormal system conditions often facing the electronics in primary equipment. New standards are needed that more accurately reflect standard operating and, especially, abnormal conditions within a substation.

Recently, KEMA Laboratories, in cooperation with Liander, a major DSO in the Netherlands, tested an “intelligent” MV substation in an integral approach. This implies that a complete ring main unit, including transformer, IED and switchgear is submitted to a number of switching tests in full power conditions.

The idea is to verify the integrity of the electronics and its output, during switching operations, the arcs, sparks and transients of which might jeopardize the micro-electronics. A realistic test environment was created, including a long cable to reproduce actual transients. There were some interesting lessons to learn. First of all, the switchgear had no classical control, but could only be remotely operated through the DSO’s wireless network. This caused some synchronization issues leaving the test-engineer outside his comfort zone of accurate control of the test-object. Also, some unexpected effects of the switching operations could be observed in the power supply chain of the electronics, which needs further study.

This is a real challenge for components that typically operate at very low voltage levels. Unprotected Internet of Things devices simply will not survive. We will need more robust devices and these will need to be thoroughly tested under realistic conditions, preferably in an integrated approach together with the primary equipment they are controlling.

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