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lecture12

# lecture12 - EE 740 Professor Ali Keyhani Lecture#12...

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EE 740 Professor Ali Keyhani Lecture #12 Homework Problems

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Problem: Consider the power system given below: Assume Sb = 10 MVA and voltage base of 13.2 kV for the generator and perform the following: 1) Assume the generator voltage is set at 10% above its rated value, and the load connected to bus (D) is equal to 5 MW at a pf of .9 lagging. Compute the per-unit model for this system. 2) Compute the load voltage (bus D). 3) Compute the active and reactive power supplied by bus (A). 4) Compute the active and reactive losses. 13.2kV 13.2/132kV 5 MVA 10% A B C D Load 1.0 + j100 10 MVA 138/69kV 8% Y Y
Vb = 13.2 kV X T1 = j.10 (10/5) = j.20 pu X T2 = j.08 (138/132) 2 = j.0874 pu Zb BC = (132) 2 /10 = 1742.4 Zpu BC = (10+j100)/1742.4 = 5.7x10 -3 + j.0573 S = 5/.9 cos -1 .9 = 5.55 25.84 ° Spu = .555 25.84 ° = -(0.5 + j0.241) θ I 1 = Y 11 Y 12 V 1 = j -2.9 2.9 V 1 I 2 Y 21 Y 22 V 2 2.9 -2.9 V 2 S 2 = V 2 I 2 * = -(0.5+j0.2411) = V 2 I 2 * I 2 = [ -(0.5+j0.2411)*] / V 2 13.2 kV 5 MVA 13.2/132 kV 10% Sb = 10 MVA 10 MVA 138/69 kV 8% 10+j100 Vb = 132kV Vb = 66kV 5 MW pf = .9 lagging A B C D S G A D R+jX X=0.344 R=5.7x10 -3 =tan -1 X/R = 89.05 Z AD =R+jX=jX=j.344 V 1 =1.1 pu Y AD =1/Z AD =-j2.9

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Assume V 2 = 1 0 ° I 2 = [-0.5 + j0.2411] (S 2 / V 2 )* = I 2 = Y 21 V 1 + Y 22 V
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