(a) The bus impedance matrix for a three-bus power system

Chapter , Problem 7.18

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(a) The bus impedance matrix for a three-bus power system is Zbus _ j 0:12 0:08 0:04 0:08 0:12 0:06 0:04 0:06 0:08 2 6 4 3 7 5 per unit where subtransient reactances were used to compute Zbus. Prefault voltage is 1.0 per unit and prefault current is neglected. (a) Draw the bus impedance matrix equivalent circuit (rake equivalent). Identify the per-unit self- and mutual impedances as well as the prefault voltage in the circuit. (b) A three-phase short circuit occurs at bus 2. Determine the subtransient fault current and the voltages at buses 1, 2, and 3 during the fault. (b) For 7.18 Repeat for the case of Zbus _ j 0:4 0:1 0:3 0:1 0:8 0:5 0:3 0:5 1:2 2 6 4 3 7 5 per unit