Development of a Methodology for Studying Digital Instrument Transformers with the Digital Ground Faults Relay Protection Devices

Single-phase ground faults (SPGF) are the most common type of faults in 6(10) kV distribution networks. In the initial stage, the SPGFs are, as a rule, of an arc intermittent nature. Overvoltages in the case of SPGF (including arc), the presence of higher harmonic components in currents and voltages affect the operation of measuring transformers and relay protection devices that are connected to them. The article presents a methodology for the experimental study of digital current and voltage transformers (DCVTs) 6(10) kV (developed in Ivanovo State Power Engineering University) with digital relay protection devices. The paper presents a diagram of the test facility, as well as the results of testing the technique. The central element of the installation is the real-time simulation complex (RTDS). The quantitative characteristics of the SPGF modes obtained in laboratory conditions, and the results of the operation of the relay protection function from SPGF, with connection to the DCVT, are presented. It was found that the protection functions of two digital relay protection devices works the same when connected to the "reference" SV source and to the 6(10) kV DCVT.