Electric Renewable Energy Systems

18.4.7. Systematic fault analysis using Z_bus matrix

For large networks, this method is applicable. Consider the network shown in Figure 18.32. Assume a three-phase fault at bus k has occurred through fault impedance Z_f.

Figure 18.32 Fault at bus k.

Prefault-bus voltages are obtained from load-flow solution and are a column vector.

$V_{\text{bus}}(0)=\left[\begin{array}{c}\hfill V_1(0)\hfill \\ \hfill ⋮\hfill \\ \hfill V_k(0)\hfill \\ \hfill ⋮\hfill \\ \hfill V_n(0)\hfill \end{array}\right]$

Short circuit currents are larger than steady-state values and hence can be neglected. Represent the bus load by a constant impedance evaluated at the prefault bus voltage, that is,

$Z_{i\text{L}}=\frac{{\left|V_i(\right|}^{}}{}$