Coordinator: Jari Hällström

Non-conventional instrument transformers (NCITs) typically provide transduction in the form of a low-level electrical signal that needs to be digitized at the sensor location and transmitted in digital form to a merging unit which then encodes the sampled values via the Ethernet according to IEC61850-9-2. Alternatively, conventional systems can be retrofitted with stand-alone merging units (SAMU), which accept standard current and voltage inputs and digitize and format them for transmission.

A few reports have been published on test systems deploying NCITs communicating over the IEC 61850-9-2 process bus, which mostly shadow a standard system already installed, however the tests mainly focused on basic functionality and bus delay issues, as this is a major concern for systems that must operate over an Ethernet connection in real time. The detailed measurement of electrical quantities and the traceability of measurement results have only received minor attention up to now.

This leads to a need to develop the metrological infrastructure needed to offer calibration services for non‑conventional current and voltage sensors. An additional goal is the traceable characterisation of commercially available test sets which have been designed to calibrate these sensors but for which there are no effective calibration services available. Traceability issues and technical challenges such as interfacing with the digital output format which is typical of the novel sensors will both be addressed.

This is achieved by developing a platform for traceable measurements of all the components of the measurement chain: from the blocks that perform digitization and transmission in retrofitted conventionally-equipped substations to the NCITs themselves. The aim is to facilitate the homogeneous deployment of NCITs and IEC-61850 based technology in Europe by:

• Development of calibration facilities for validating sensors with a non-conventional analogue output (such as EVT, ECT).
• Development of calibration facilities for validating SAMUs.
• Development of calibration facilities for validating sensors with a digital output.
• Development of calibration facilities for validating commercial test sets for non-conventional current and voltage sensors.
• Development of standardised tests and sequences including intermodulated voltages and currents emulating grid conditions.

For more information, see the project webpage >>