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EMPIR project develops measurement methods needed for power distribution and transmission

Completed EMPIR project Metrology for the next-generation digital substation instrumentation (17IND06, FutureGrid II) developed the calibration methods needed for the new digital hardware used in networks for power transmission and distribution.

As a result, greater accuracy will be achieved, with measurements traceable to primary standards held by National Measurement Institutes. To encourage uptake of the results from this project, industry and standards organisations were informed through workshop events, journal papers and good practice guides.

The project was successfully concluded by establishing measurement methods and measurement setups for testing instrumentation in future digital substations. The key achievements of the project support a number of different target groups including instrumentation manufacturers and grid system operators.

The outputs of the project also benefit the European public as end-users of the electricity grid by ensuring it is stable and well-monitored.

Publicly available Good Practice Guide

A Good Practice Guide on the performance of the reference standard SAMU as a calibration reference for the calibration of instruments with digital input or output, describes a new method for analogue front-end delay calibration of a reference SAMU. Before the FutureGrid II project, no such reference SAMU had existed, and no institute worldwide would have been able to offer calibration service for one. The accuracy achieved fully satisfies requirements as a reference standard.

Achievements of the project which will bring benefits to instrument manufacturers

• Waveform generation of complex low-level signals was applied to, and implemented in, the high voltage and high current testing for instrument transformers and sensors. Further, a new (first-in-the-world) universal comparator was finalised, able to compare any type of voltage or current sensor in a frequency spectrum up to 9 kHz.
• An integrated Stand-Alone Merging Unit (SAMU) with Phasor Measurement Unit (PMU) that implements Sampled-Values based on IEC 61869-9 was built and tested.
• Project partners PTB, INRIM, VSL and MIKES are preparing to offer new/improved customer services for the laboratory calibration of digital voltage and current sensors as well as SAMUs based on new or revised Calibration and Measurement Capabilities entries resulting from project developments.
• The project consortium have contributed to a committee draft of the IEC Technical Committee 38/ IEEE TC39 JWG55 Technical Report IEC 61869-105 Recommended Practice for Uncertainty Evaluation in the Calibration of Instrument Transformers  

Achievements of the project which will bring benefits to grid system operators

• A new measuring system was developed, capable of carrying out real-time calibrations of large digital instrument transformers installations in substation busbars by comparison to a traceable voltage transformer. It contains a completely new capability of simultaneously analysing many different sampled value data streams to obtain a distributed power quality measurement functionality within a smart substation.
• A multi-purpose calibration system for on-site measurements was built. Each part of the system can be used individually for current or voltage transformer calibrations, including those with digital outputs. This substantially improves previous state of the art on-site measurement capabilities in Europe.
• In the Good practice guide on reviewing accuracy and security of digital time synchronization protocols, a collected overview was presented on how to assess both the accuracy and reliability levels and relate them to the required effort, for different digital methods of synchronising clocks.
• Work on satellite-independent PMU measurement using distributed photonic sensors was completed. This yielded a completely new technology for conducting wide area monitoring measurements without the need of time transfer to remote locations. This way, a measurement system covering a geographically significant area could be established, with only modest requirements for timing infrastructure.

General benefits

All of the key outputs of the project facilitate the use of new next-generation and digital instrumentation with new suitable test and calibration systems, new or enhanced measurement capabilities, and contributions to improved standardisation by providing input or recommendations to standards related to instrument transformer technology (IEC TC38) and related to time synchronisation (IETF, IEEE).

Project Coordinator Enrico Mohns from PTB said

‘The successful completion of this European metrology project brings the urgently needed implementation of the metrological fundamentals in practice for the future digital instrumentation in high voltage substations. This now enables the new digital instrumentation to be traceable to national standards, in the same way that previously existed for the traditional analogue instrumentation’.

The project results are directly impacting the competitiveness of European industry in their endeavours on the international market for electricity supply, by providing them with newly available metrology tools to unambiguously prove the quality of their equipment.

This EMPIR project is co-funded by the European Union's Horizon 2020 research and innovation programme and the EMPIR Participating States.

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