D2 - Good practice guide on the calibration of commercial SV enabled instrumentation with sampling rates up to 96 kSPS Organisation

Digital substations are becoming a cornerstone of the future electrical energy transmission and distribution network. These substations rely heavily on digital instrumentation, served by instrumentation capable of producing Sampled Values (SV) in compliance with the IEC 61850 and IEC 61869 standards. Stand-alone Merging Units (SAMUs) are used to digitize analog signals from conventional instrument transformers and transmit these signals in real-time via Ethernet-based process buses. This makes it possible to combine existing and proven analog voltage and current sensors with digital measurement and protection devices.
With the introduction of SAMUs new calibration procedures and uncertainty estimation methods are needed to characterize these devices. Characteristics such as amplitude and phase displacement are extracted from the digital SAMUs SV streams and compared to a reference to determine the accuracy class. This is done on test beds that have been developed and calibrated for their gain and absolute phase relative to the 1PPS signal at various NMIs. In this work, the test benches that have been developed by the participating laborato-ries (NMIs and others) , a description of these testbenches and their performance can be found in the annex. During the development of these testbenches some important knowledge and pitfalls have been found and are shared.