Against a black background is an image of the world showing European countries with cities connected with glowing gold lines to represent the electrical networks
Case Study Overview

Metrology and standardisation for components of European electrical grids

The European electrical grid is one of the largest in the world, supplying nearly 600 million EU citizens. However, at the start of 2020 vital metrology and standardisation was missing on how many types of grid components should be tested to withstand their operational environment. Unless addressed, partial power failure or blackouts could result, leading to dissatisfied and vulnerable consumers and potentially high repair costs.

Challenge

To prevent electrical failures in the grid, such as short circuits and breakdowns and resulting blackouts, it is essential that components of the electricity grid, including cabling, insulators, switchgears, and transformers, are tested to ensure suitability for their operating environments.

As well as the high voltage alternating current (HVAC) or direct current (HVDC) in the transmission grid (> 220 kV), internal and external overvoltages can occur. External overvoltages, from natural occurrences such as lightning strikes on power lines “Lightning Impulses” (LI) or internal overvoltages, caused by either the technically required addition or removal of connected devices, “Switching Impulses” (SI), can reach hundreds of kV in microseconds. These transient loads are superimposed with the undisturbed voltage in the electricity grid generating a so called combined or composite waveform. This can cause damages to lines, substations and any other grid components.

The IEC 60060 series of standards details the requirements for testing components using HVAC or HVDC combined with SI or LI waveforms. The components’ response to these electrical stresses are measured using instruments called ‘universal dividers’.

However, at the start of 2020 these universal dividers lacked any form of standardisation for the combined and composite waveforms, including how complete measurement systems should be calibrated or how accurately they can measure the combined or composite waveforms used during testing. In response, the relevant standards were being updated and there was an urgent need to verify the existing dividers currently available.

Solution

During the HV-com² project, a new reference universal divider was designed and built using off-the-shelf components connected in series and in parallel, containing DC, AC, LI and SI voltage measuring systems. The new divider was then characterised, indicating a measurement uncertainty of less than 0.1 % for all voltage types.

This reference divider was then used during two measurement campaigns to assess two commercially available universal dividers, one of which was provided by the company HIGHVOLT. This included a comparison of each commercial divider against the other over an extended voltage range for DC + SI/LI and AC + SI/LI for combined and composite waveforms up to at least 1100 kV peak voltage. Results indicated that the commercial dividers demonstrated high overall accuracy for all superimposed voltage tests, especially regarding their dynamic behaviour.

In addition, the comparisons indicated that, for the first time, universal dividers could be calibrated in the laboratory with metrological traceability.

Impact

HIGHVOLT, based in Germany, has been providing cutting edge solutions for the electrical network for over 120 years, and offers a comprehensive portfolio for testing of transformers, cables, and air-insulated switchgears, instrument transformers, and arresters. The company supplied the universal reference voltage divider for testing in the HV-com² project, one of its MCR range. It is now one of the first in the world to demonstrate metrological traceability for high voltage impulse tests for combined and composite waveforms in line with the new IEC 60060 standards that came into force in 2025.

This information, confirmed by PTB, one of the leading National Metrology Institutes, can now be passed onto HIGHVOLT’s customers, giving them confidence that they in turn can calibrate their equipment to meet these new standards.

In addition, the determination of the uncertainty of existing voltage dividers and measurement systems made possible by the HV-com² project will help ensure the security of the electricity supply and support the European HV instrument manufacturing industry in demonstrating that their products are fit for their operational environment.

Providing the instruments and metrology to protect the electricity grids

In the HV-com² project voltage generators were designed and built, along with evaluation software, to reliably determine the superposition of impulse voltages with HVAC or HVDC measurements, and any related detrimental effects due to combined and composite voltage tests.

Two campaigns were undertaken using the universal reference divider developed by the project, demonstrating that commercially available universal dividers were capable of analysing the applied DC+LI/SI superimposed voltages with the accuracy required for high voltage testing. Recommendations based on these results were included in the revision of IEC 60060-1 and IEC 60060-2, published in 2025.

Interlaboratory comparisons were performed using a 900 V voltage calibrator, used for calibrating digital recorders and other components of voltage measurement systems, to verify the suitability of the IEC 61083-1 standard.

The work of the project will ensure the resilience of the components used in high voltage grids and help prevent the disruption caused by power outages and blackouts.

Contact

  • Category
  • Standardisation,
  • Energy,
  • EMN Smart Electricity Grids,
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