Question

The single line diagram of a simple power system is shown in Figure 1. The system data are given in the table below. Choose a base power of 100 MVA and a base voltage of 132kV in Line4. Draw the impedance diagram of the system. Calculate and mark all impedances in pu on the diagram. Calculate the line to line voltage of Bus 3 in pu and in kV if the motor draws its rated power at rated voltage and pf = 0.7 lagging.

Answer 1

Base 100 MVA, 132 KV generator 1: 60 MVA, 12 k v, x = 0.1 = 10 x Base Qualities 100 MVA, 10 k v generator side i.e T/F primary X_G 1 = 0.1 times (100/60) times (12/10)^2 = 0.24 generator 21: 60 MVA, 15 kv, alpha = 0.05 Base = 100 MVA, 15 k v X_G 2 = 0.05 times (100/60) times (15/15)^2 = 0.0833 Transformer 1: - 100 MVA, 10 Vertical-bar 132, 8 % Base - 100 MVA, 132 k v X_T_1 = 0.08 times (100/100) times (132/132)^2 = 0.08 Transform - 2: 100 MVa, 15 Vertical-bar 132 k v, 6 % Base: 100 MVa, 132 kV X_T_2 = 0.06 times (100/100) times (132/132)^2 = 0.06 Transformer 3: - 50 MVA, 132/22 KV, 10 % Base: - 100 MVA, 132 KV X_T_3 = 01. times (100/50) times (132/132)^2 = 0.2 Transformer 4: - 50 MVA, 132/22 KV, 5 % Base: 199 MVA, 132 KV X_T_4 = 0.05 times (100/50) times (132/132)^2 = 0.1 Motor: - 45 MVA, 20 KV,