A High-Precision and Low-Complexity Framework for Calibration of Stand-Alone Merging Units

A novel technique is presented for the synchronization of sampled value (SV) streams generated according to the IEC 61869-9 and IEC 61850-9-2 standards by devices aligned via the precision time protocol (PTP), with measurement data obtained from reference instruments that do not support PTP. The proposed solution, in conjunction with a precharacterized sampling digital multimeter (DMM), enables automated calibration of stand-alone merging units (SAMUs). A thorough characterization of the phase error of the DMM across all voltage and current ranges in sampling mode is also reported.