BARC-2018 EE: Power System Quiz 4

Two generator units G1 and G2 are connected by 15 kV line with a bus at the mid-point as shown below.

G1 = 250 MVA, 15 kV, positive sequence reactance X = 25 % on its own base
G2 = 100 MVA, 15 kV, positive sequence reactance X = 10 % on its own base
L₁ and L₂ = 10 km, positive sequence reactance X = 0.225 Ω/km
For the above system, the positive sequence diagram with the p.u values on the 100 MVA common base is

Fault current of a line to ground fault and LLL fault for an unloaded generator is same. If X₁ = 0.3 pu, X₂ = 0.2 pu and X_O = 0.04 pu. Then calculate value of inductive reactance (X_n) required for natural grounding (in pu).

The reluctance torque of a 3-phase salient pole synchronous generator with direct and quadrature axis reactance, x_d and x_q, respectively, is proportional to

The KVA taken by a 10 km long, 3-phase, 3-core, cable, if the capacitance measured between any two cores is 0.3 μF/Km when it is connected to 10 KV, 50 Hz bus-bar is

In Gauss-Seidel method for load flow problems, what effect will occur, if the correction in voltage at each bus is multiplied by a suitable acceleration factor?