The bus impedance matrix (Zbus) of a power network describes the open-circuit driving-point and transfer impedances relating bus voltages to current injections, and unlike the bus admittance matrix (Ybus) it cannot be formed by inspection — it must be built incrementally through a step-by-step Zbus building algorithm. This algorithm incorporates each network branch by one of four canonical modification types (new bus to reference, new bus to existing bus, existing bus to reference, and branch between two existing buses), using Kron reduction to eliminate auxiliary rows/columns whenever no new bus is actually added. The resulting Zbus underlies symmetrical and unsymmetrical short-circuit (fault) analysis in power system analysis, particularly for large networks where direct Ybus inversion is computationally prohibitive.
The bus impedance matrix (Zbus) of a power network describes the open-circuit driving-point and transfer impedances relating bus voltages to current injections, and unlike the bus admittance matrix (…