In power system analysis, asymmetrical (unbalanced) fault analysis extends the Z-bus method used for symmetrical faults by building separate positive-, negative-, and zero-sequence bus impedance matrices via symmetrical component transformation and assembling them into a composite sequence bus impedance matrix, since an asymmetrical fault couples the three otherwise-independent sequence networks at the fault point through a fault impedance (or admittance) matrix whose structure depends on fault type. The post-fault sequence voltages and fault currents at any bus are computed from the pre-fault voltages, the sequence bus impedance matrix, and the fault impedance/admittance matrix using the Thevenin-equivalent relationship generalized from the symmetrical-fault case, providing a systematic, computer-programmable method for solving faults of any type on large power systems.
In power system analysis, asymmetrical (unbalanced) fault analysis extends the Z-bus method used for symmetrical faults by building separate positive-, negative-, and zero-sequence bus impedance matr…