Symmetrical component (sequence network) analysis models unbalanced three-phase power system behavior by transforming coupled phase-domain impedances into three decoupled sequence networks—zero, positive, and negative—each characterized by an independent self-impedance derived from the self and mutual impedances of the physical system, applicable separately to transmission lines, synchronous machines, and transformers. Positive-sequence networks alone carry the source voltage (since machines are designed to generate balanced positive-sequence EMF), while negative- and zero-sequence networks are passive ("dead") networks that become energized only under unbalanced conditions, with the zero-sequence network topology for transformers and grounded equipment further governed by winding connection type (star grounded, star ungrounded, delta) and neutral grounding path availability.
Symmetrical component (sequence network) analysis models unbalanced three-phase power system behavior by transforming coupled phase-domain impedances into three decoupled sequence networks—zero, posi…