Figure 3 shows the one-line diagram of a three-bus power system with generation at bus X. The magnitude of voltage at bus X is adjusted to 1.05 per unit. The scheduled loads at buses Y & Z are as on the diagram. Line impedances are marked in per unit on a 100 MVA base. i. Determine the bus voltages. Calculate branch current and power flow after 1

Figure 3 shows the one-line diagram of a three-bus power system with generation at bus X. The magnitude of voltage at bus X is adjusted to 1.05 per unit. The scheduled loads at buses Y & Z are as on the diagram. Line impedances are marked in per unit on a 100 MVA base. i. Determine the bus voltages. Calculate branch current and power flow after 1

Power System Analysis and Design (MindTap Course List)

6th Edition

ISBN:9781305632134

Author:J. Duncan Glover, Thomas Overbye, Mulukutla S. Sarma

Publisher:J. Duncan Glover, Thomas Overbye, Mulukutla S. Sarma

Chapter9: Unsymmetrical Faults

Section: Chapter Questions

Problem 9.5P

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Equipment ratings for the five-bus power system shown in Figure 7.15 are as follows: Generator G1:Â Â Â Â 50Â MVA,Â 12kV,Â X=0.2 per unit Generator G2: 100Â MVA, 15 kV, X=0.2 per unit Transformer T1: 50 MVA, 10 kV Y/138kVY,X=0.10 per unit Transformer T2: 100 MVA, 15 kV /138kVY,X=0.10 per unit Each 138-kV line: X1=40 A three-phase short circuit occurs at bus 5, where the prefault voltage is 15 kV. Prefault load current is neglected. (a) Draw the positive-sequence reactance diagram in unit on a 100-MVA, 15-kV base in the zone of generator G2. Determine (b) the ThĂ©venin equivalent at the fault, (c) the subtransient fault current in per unit and in kA rms, and (d) contributions to the fault from generator G2 and from transformer T2.
Equipment ratings for the four-bus power system shown in Figure 7.14 are as follows: Generator G1: 500 MVA, 13.8 kV, X=0.20 per unit Generator G2: 750 MVA, 18 kV, X=0.18 per unit Generator G3: 1000 MVA, 20 kV, X=0.17 per unit Transformer T1: 500 MVA, 13.8/500YkV,X=0.12 per unit Transformer T2: 750 MVA, 18/500YkV,X=0.10 per unit Transformer T3: 1000Â MVA, 20/500YkV,X=0.10 per unit A three-phase short circuit occurs at bus 1, where the prefault voltage is 525 kV. Prefault load current is neglected. Draw the positive-sequence reactance diagram in per unit on a 1000-MVA, 20-kV base in the zone of generator G3. Determine (a) the ThĂ©venin reactance in per unit at the fault, (b) the subtransient fault current in per unit and in kA rms, and (c) contributions to the fault current from generator G1 and from line 1-2.
Figure below shows the single-line diagram of three-bus power system with generation at bus 1 and bus 3. The voltage at bus 1 is V₁ = 1.025/0° per unit. The voltage magnitude at bus 3 is fixed at 1.05 per unit with a real power generation of 250 MW. The scheduled load on bus 2 is marked on the diagram. Line impedances are marked in per unit on a 100 MVA base. Line resistances and line charging susceptances are neglected. By using Gauss-Seidel method and initial estimates of V₂(0) = 1.020° and V3(0) = 1.0520°, determine V₂ and V3. Perform calculation for one iteration. V₁ = 1.025/0° j0.1 Slack Bus j0.2 j0.4 j0.2 3 j0.1 250 MW 150 Mvar |V3|=1.05 P3 = 250 MW
In a 7-bus system, the double line fault is occurred at bus -5. During fault the positive sequence potential difference between the bus-4 and bus-1is found to be 0.0175. what is the line impedance which is connected between bus-4 and bus-1 if the current flowing through transmission line is -j 0.148? Select one: O a. -jo.182 O b. +j0.1182 O c. -jo.1182 O d. +j0.182
Figure shows the one-line diagram of a simple three-bus power system with generation at buses 1 and 3. The voltage at bus 1 is V1 is 1.025 at an angle of 0◦ per unit. Voltage magnitude at bus 3 is fixed at 1.03 pu with a real power generation of 300 MW. A load consisting of 400 MW and 200 MVAr is taken from bus 2. Line impedances are marked in per unit on a 100 MVA base. (a) Construct Ybus matrix for the system in Figure (b) Using Gauss-Seidel method and initial estimate of V2(0) = 1.0 + j0 and V3(0) = 1.03 + j0 and keeping |V3| = 1.03 pu, determine the phasor values of V2 and V3. Perform two iterations.
1. FIGURE 52 shows the one-line diagram of a simple three-bus power system with generation at bus I. The voltage at bus l is V1 = 1.0L0° per unit. The scheduled loads on buses 2 and 3 are marked on the diagram. Line impedances are marked in per unit on a 100 MVA base. For the purpose of hand calculations, line resistances and line charging susceptances are neglected a) Using Gauss-Seidel method and initial estimates of Va 0)-1.0+)0 and V o)- ( 1.0 +j0, determine V2 and V3. Perform two iterations (b) If after several iterations the bus voltages converge to V20.90-j0.10 pu 0.95-70.05 pu determine the line flows and line losses and the slack bus real and reactive power. 2 400 MW 320 Mvar Slack 0.0125 0.05 300 MW 270 Mvar FIGURE 52
QUESTION 3 The power system network is shown in Figure 3. The magnitude of voltage at bus 1 is adjusted to 12 0° per unit, buses 2 and 3 are the load buses. Line impedances are marked in per-unit on 100 MVA base and the charging susceptances are neglected. Determine the bus voltage at load 2 and 3 using the Gauss-Seidel iteration method (accurate to four decimal places). Perform calculation for two iterations. jo.033 P= 400 Mw HQu= 320 MVar Vi = 120° Figure 3 10.05 +P= 300 MW 70.0125 +QF 270 MVar
Q2\ The one-line diagram of a simple power system is shown in figure below. All impedances are expressed in per unit (pu) on a common MVA base. All resistances and shunt capacitances are neglected. The generators are operating on no load at their rated voltage. A three-phase fault occurs at bus 1 through a fault impedance of Zf = j0.08 per unit. Using Thevenin's theorem obtain the impedance to the point of fault and the fault current in per unit. Determine the bus voltages and line currents of generators during fault. X₁ = = 0.1 XT-0.1 3 1 to ojo XL=0.2 2 040 X₁ = 0.1
b) The one-line diagram for a simple power system is given in Figure 1(b). į. Draw the impedance diagram of the system. i. Construct the bus admittance matrix, Xeus and bus impedance matrix, Zous of the system. I. Evaluate the fault current, bus voltages and line current during the flow when a balanced three-phase fault occurs on bus 1. bus 1 bus 2 j65 N G G 25 MVA 25 MVA 13.8 kV 15% 13.2/69 kV 11% 25 MVA 69/13.2 kV 11% 15 MVA 13 kV 15% Figure 1(b) m
QUESTION 5 a) Obtain the sequence networks reduced to their Thevenin equivalents for the system shown in Figure 4 in the case of a fault at F. Prefault is VF = 1.05Z 0° per unit. System data in per unit on the same base are given as follows: G1 : XI = 0.2 p.u. G2 : XI = 0.33 p.u. X2 = 0.12 p.u. X2 = 0.22 p.u. Хо - 0.06 р.u. Хо- 0.066 р.u. T1:XI =X2 = Xo = 0.2 p.u. T2:X = X2 = Xo 0.225 p.u. T3 :X1 =X2 = Xo = 0.27 p.u. T4 :X1 = X2 = Xo = 0.16 p.u. L1 :XI = X2 = 0.14 p.u. Xo = 0.3 p.u. L2 :X1 = X2 0.35 p.u. Xo = 0.6 p.u. T1 T2 L1 G1 G2 L2 T4 T3 Figure 4 b) Calculate the per-unit subtransient fault current in phase a, b, c for a bolted three phase to ground short circuit at fault F in Figure 4. Justify your answer.
A single-line diagram of a four-bus system is shown in fiugre. Equipment ratings and per-unit reactances are given as follows.Machines 1 and 2: 100 MVA 20 kV; X1= X2 = 0.2; X0= 0.04 Xn= 0.05 Transformers T1 and T2: 100 MVA 20Y/345Y kV; X1 = X2 = X0 = 0.08. On a base of 100 MVA and 345 kV in the zone of the transmission line, the series reactances of the transmission line are X1 = X2 = 0.15 and X0=0.5 per unit. (a) Determine the bus impedance matrix for each of the three sequence networks. (b) Assume the system to be operating at nominal system voltage without prefault currents when a bolted single-line-toground fault occurs on phase A at bus 3. Compute the fault current, the current out of phase C of machine 2 during the fault, and the line-toground voltages at the terminals of machine 2 during the fault. Total detailed answer is needed. The figure is attached.
Problem 5 Consider the system shown in the single-line diagram of Figure (3). All reactances are shown in per unit to the same base. Assume that the voltage at both sources is 1 p.u. a- Find the fault current due to a bolted- three-phase short circuit at bus 3. b- Find the fault current supplied by each generator and the voltage at each of the buses I and 2 under fault conditions. 0.04 p.u. 0.2 p.u. 0.06 p.u. 0.2 p.u. 0.25 p.u. G, 0.2 p.u. 0.2 p.u. 0.06 p.u. 0.06 р.и. 3 0.25 p.u. 0.25 p.u. G, Figure (3) Single-line diagram for Problem 5 ele