Write a MATLAB program to calculate the three-phase fault current for a fault at F in the figure below, with the network normal, and then with one line removed at a time from service. The positive-sequence impedance values are given in the below table.

Use the assumption that all prefault resistance values are 1+j0 pu, neglect all resistance values.

Calculate the contribution to the fault flowing through the circuit breaker B1, and the voltage at that bus. For each calculated case, consider the 2 possibilities: CB B2 open and closed. The later is known as the "stub-end" fault.

Using the usual assumptions about the positive and negative sequence impedances of the network elements, what are the currents at breaker B1 for a phase b-c fault for each of the faults in the first part? What is the voltage between phases b and c for each case?

7 Q LO B2 B1 2 Q cedee From To Positive sequence impedance 1 2 2 2 3 2 6 5 4 5 6 5 6 7 0.0 + 0.1 0.05 + j0.15 0.04 + j0.2 0.01 + j0.1 0.015 + j0.15 0.01 + j0.19 0.01 + 0.19 0.03 + 0.1 0.0 + j0.08 3 4 4 6