The Use of Symmetrical Components in Electrical Protection

In some situations, the symmetrical components of voltage and current are more sensitive to electric faults compared to their phase-domain counterparts. For this reason, several protection relays operate on symmetrical components and many protection engineers continue to develop protection algorithms that rely on these quantities. This paper reviews the literature on the use of symmetrical components in electrical protection and sorts it in categories covering line protection, generator/motor protection, transformer protection and protection of distribution networks and microgrids. The review shows that symmetrical components are used by over-current/-voltage elements, distance relaying, directional algorithms, differential schemes, adaptive protection and protection algorithms based on relationships of symmetrical components. This paper also presents, in short, the theoretical background of symmetrical components and their derivation from the phase-domain quantities.