Symmetrical component transformation resolves an unbalanced set of three-phase quantities into three balanced (symmetrical) sets — positive-, negative-, and zero-sequence components — using a fixed unit-magnitude, 120°-phase-shift operator, enabling analysis of asymmetrical faults on an otherwise balanced three-phase network. Because power-system elements are individually designed to be symmetrical, the transformation decouples the network into three independent sequence networks connected only at the point of unbalance, and the transformation is power-invariant, meaning three-phase complex power equals the sum of the sequence-component powers. This belongs to power system fault analysis, extending single-phase-equivalent analysis (valid only for symmetrical/balanced faults) to the general asymmetrical-fault case, and provides the sequence-network impedance models (e.g., for star- and delta-connected loads) that underlie subsequent unbalanced fault studies.
Symmetrical component transformation resolves an unbalanced set of three-phase quantities into three balanced (symmetrical) sets — positive-, negative-, and zero-sequence components — using a fixed u…