Draw the positive-, negative- and zero-sequence diagrams for the network and then do the follo A. Determine Zbus(pos), Zbus(neg) and Zbus(zero). B. Calculate the fault-currents on all the buses for all types of faults. Do a fault study on the power system shown in Figure 1. T3 G3 G1 T1 T4 G4 T2 G2 Figure 1 Gr: 1 000 MVA G2 1 000 MVA G3: 500 MVA Ga. 750 MVA Xa = X2 = 0,18p.u Xo = 0,07pu X = X2 = 0,2p.u 15 kV 15 kV X = 0,1p.u 13,8 kV Xa = X2 = 0,15p.u Xo = 0,05pu 13,8 kV Xa = 0,3p.u X2 = 0,4p.u Xa = 0,1p.u T1: YND11 1 000 MVA 765/15 kV X = 0,1p.u T2: YND11 X = 0,1p.u X = 0,12pu X = 0,11p.u 1 000 MVA 765/15 kV T3: YNYO 500 MVA 765/15 kV 750 MVA 765/15 kV Xa = 150 n X = 100 n L12: X1 = 50 n L13: X1 = 40 n L32: X1 = 40 0 Xo = 100 n Use Sp = 1 000 MVA and the pre-fault voltage on the transmission lines of 765 kV.