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The outdoor measurement campaign at PTB during an intercomparison of all four 1000+ kV dividers; image: Courtesy of PTB

Ultra-high voltage grids transmit electricity more efficiently than current networks but require new methodologies

EMPIR project Metrology for future energy transmission (19ENG02, FutureEnergy) is developing new methods and hardware to extend the traceable measurements for ultra-high voltage direct current (UHV-DC) of 1000kV and above, which is more efficient over long distances than the alternating current currently used. 

Technical details of measurement campaigns

In order to establish traceability to 1200 kV with a target measurement uncertainty of 40 µV/V, in total seven new 200 kV HV modules were built. One HV module increases the 1000 kV modular divider to 1200 kV for RISE (Sweden). Five HV modules increase the 200 kV modular divider to 1200 kV for PTB (Germany). One HV module increases the 200 kV modular divider to 400 kV for TUBITAK (Turkey). Two complete sets of HVDC dividers are now available for calibration with traceability to 1200 kV in Europe from RISE and PTB, with an expanded measurement uncertainty of 20 µV/V for 1200 kV.

Traceability of three types of UHV-DC systems were established through two measurement campaigns, one at RISE and one at PTB.

In the first campaign in total three HVDC measurement systems were set up in the lab of RISE in March 2022 for the first calibration. Prior to the HV calibration a LV calibration of all collected system components was done in the precision lab of 16 HV modules and six LV arms. The 1200 kV calibration was performed in a step-up procedure with 200 kV, 600 kV, 800 kV to 1200 kV. An intercomparison took place between two 1200 kV dividers from RISE and PTB and an 800 kV configuration combining the dividers from TUBITAK, VSL (Netherlands) and VTT (Finland). An expanded measurement uncertainty of 20 µV/V for 1200 kV will be claimed.

In the second campaign two new divider designs were developed for UHV-DC operation. The first shielded RCRC divider, which are two dividers in one and one of which is shielding the other, was designed and assembled by PTB with support from RISE and VTT. Five 400 kV UHV-DC divider modules were built to reach 2000 kV. The second design is an unshielded RCR divider that was designed and calibrated by RISE with support from PTB and VTT. Two 500 kV modules were built for the RCR divider to reach 1000 kV.  An UHV-DC generator was designed by PTB and set up for 2000 kV at an outdoor open area field test range in May-June 2022. During the campaign two 1200 kV HVDC dividers were intercompared with the 2000 kV RCRC divider and the 1000 kV RCR divider. An expanded measurement uncertainty of 100 µV/V was reached at 1600 kV for the RCRC divider and 80 µV/V at 1000 kV for the RCR divider.

Project Coordinator Alf-Peter Elg from RISE said

‘The two measurement campaigns have successfully been completed. Two precision measurement systems for 1200 kV are ready for service, and the 1200 kV precision divider of RISE has already been taken into service in several calibrations. The 1600 kV divider by PTB is partly also in use and the universal RCR divider by RISE, which can measure any waveform and can be extended to 1600 kV, has been used in 30+ calibrations during 2022. Next steps will be publications and conferences and a stakeholder workshop being prepared at PTB end of April’.

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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