Directional protection of substation equipment

The introduction of microprocessor technology in the management of energy objects, including diagnostics, into relay protection and automation, allows combining and unifying relay protection of individual objects into a single system. One of the methods of unified relay protection may be directional protection. It is possible to develop and offer directional protection for generators, transformers, which are currently not used. An obstacle to the use of directional protection of generators and transformers is the presence of aperiodic components in the short-circuit currents, that introduce distortions in determining the angle between the short-circuit currents and voltages. At the "Power Supply" Department of the North-Eastern Federal University named after M.K. Ammosov a method that excludes aperiodic components in the secondary currents of current transformers of power system objects was developed, which made it possible to exclude incorrect actions of directional protections, including when saturating the current transformer magnetic cores. The method is based on processing four instantaneous samples of currents separated by identical sampling intervals. (paper)