Traceable calibration of digital energy meters for smart grids

Publication

VSL has developed a new test setup for the traceable calibration of digital energy meters with IEC 61850‑9‑2 sampled value inputs, addressing the growing use of digital instrumentation in electrical substations. The work has been published in IEEE Transactions on Instrumentation and Measurement.

The increasing digitalisation of electrical substations is transforming the way electrical energy is measured. Traditional analogue signals are being replaced by digital sampled value streams defined by the IEC 61850‑9‑2 standard, which introduces new challenges for the calibration and traceability of energy meters used for settlement and billing purposes.

In a recent IEEE publication, researchers from VSL present a test setup that enables the traceable calibration of energy meters with digital sampled value inputs. During calibration, the meter under test is exposed to synthetically generated voltage and current samples that simulate polyphase grid conditions. The accumulated energy reading of the meter is then compared with a reference value derived from the applied samples to determine the meter error.

As the internal processing of digital energy meters is typically unknown, additional tests were designed to identify potential error sources specific to digital measurement chains, including insufficient synchronisation and the effect of harmonics. The results demonstrate that small but non‑zero energy measurement errors can occur, highlighting the need for robust, traceable calibration methods for digital energy metering.

This work strengthens the metrological foundation for reliable energy measurements in digital substations and supports the ongoing development of smart grids.