Figure 1 shows the one-line diagram of four-bus power system with generation at bus 1 and bus 4. The voltage at bus 1 is V1 =1.05 <0° per unit. The Voltage magnitude at bus 4 is fixed at 1.11 pu with a real power generation of 250 MW. The scheduled loads on buses 2 and 3 are marked on the diagram. Line impedances are marked in per unit on a 120-MVA base. Create the admittance matrix bus using KCL method. 1 2 0.6+j0.6 V,=1.05 <0° p.u. j0.1 100MW + J100OMVAR Slack Bus j0.3 j0.3 P=250MW jo.1 150MW + j100MVAr |Vl=1.11 p.u.( 4 0.6+j0,6 3 Figure 1 0.5+j0.5

Figure 1 shows the one-line diagram of four-bus power system with generation at bus 1 and bus 4. The voltage at bus 1 is V1 =1.05 <0° per unit. The Voltage magnitude at bus 4 is fixed at 1.11 pu with a real power generation of 250 MW. The scheduled loads on buses 2 and 3 are marked on the diagram. Line impedances are marked in per unit on a 120-MVA base. Create the admittance matrix bus using KCL method. 1 2 0.6+j0.6 V,=1.05 <0° p.u. j0.1 100MW + J100OMVAR Slack Bus j0.3 j0.3 P=250MW jo.1 150MW + j100MVAr |Vl=1.11 p.u.( 4 0.6+j0,6 3 Figure 1 0.5+j0.5

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

Chapter2: Fundamentals

Section: Chapter Questions

Problem 2.38P

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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.
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
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
Q2. Figure Q2 shows the single-line diagram. The scheduled loads at buses 2 and 3 are as marked on the diagram. Line impedances are marked in per unit on 100 MVA base and the line charging susceptances are neglected. a) Using Gauss-Seidel Method, determine the phasor values of the voltage at load bus 2 and 3 according to second iteration results. b) Find slack bus real and reactive power according to second iteration results. c) Determine line flows and line losses according to second iteration results. d) Construct a power flow according to second iteration results. Slack Bus = 1.04.20° 0.025+j0.045 0.015+j0.035 0.012+j0,03 3 |2 134.8 MW 251.9 MW 42.5 MVAR 108.6 MVAR
Figure below shows one-line diagram of a simple three bus power system with generation at bus 1. Bus 1 is considered as slack bus. A load consisting of 250 MW and 110 MVAR is taken from bus 2. A load consisting of 128 MW and 35 MVAR is taken from bus 3. Line impedances are marked in per unit on a 100 MVA base. Line susceptances are neglected. G1 0.01 +10.03 V₁ = 1.040° 0.02 +0.04 Select one: O a. None of these O b. 0.9245-j0.025 O c. 0.9245+j0.025 O d. -0.9245-j0.025 e. 0.9638-j0.03 0.0125+j0.025 ·0 P2 Q2 P3 Q3 Start with flat initial estimates of ₂0) = 1 + j0 & V3⁰) = 1 + j0, and keeping |V₂| = 1 pu, find V₂(¹)
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.
The one-line diagram of a simple power system is shown in Figure below. The neutral of each generator is grounded through a current-limiting reactor of 0.25/3 per unit on a 100-MVA base. The system data expressed in per unit on a common 100-MVA base is tabulated below. The generators are running on no-load at their rated voltage and rated frequency with their emfs in phase. G Stark Item Base MVA Voltage Rating X' x² 20 kV 20 kV 20/220 kV 20/220 kV 100 0.05 0.15 0.15 0.10 0.10 220 kV 0.125 0.125 0.30 0.15 0.25 025 0.7125 0.15 100 100 0.15 0.05 0.10 0.10 0.10 100 0.10 100 100 Lu La 220 kV 0.15 220 kV 0.35 100 A balanced three-phase fault at bus 3 through a fault impedance Zf= jo.I per unit. The magnitude of the fault current in amperes in phase b for this fault is: Select one: A. 345.3 B. 820.1 C. 312500 3888888 产产

6. For a three bus power system assume bus 1 is the swing with a per unit voltage of 1.020 , bus 2 is a PQ bus with a per unit load of 2.0 + j0:5, and bus 3 is a PV bus with 1.0 per unit generation and a 1.0 voltage setpoint. The per unit line impedances are j0.1 between buses 1 and 2, j0.4 between buses 1 and 3, and j0.2 between buses 2 and 3. Using a flat start, use the Newton-Raphson approach to determine the first iteration phasor voltages at buses 2 and 3.
Three zones of a single-phase circuit are identified shown in Figure below. The zones are connected by transformers T1 and T2, whose ratings are also shown. Using base values of 33 kVA and 232 volts in zone 1, Find: 1- Draw the per-unit circuit including the per-unit impedances and the per-unit source voltage. 2- Calculate the load current both in per-unit and in amperes (actual or original value). Vs Zone 1 232.940° Vs G. 38 T₁ 30 KVA 240/480 volts Xeq = 0.10 p.u. Zone 2 Xiine = 4 Ω T₂ 20 KVA 460/115 volts Zload = Xea = 0.10 p.u. Zone 3 u 1+j2.2 Ω 2
The figure below shows the one-line diagram of a four- bus power system. The voltages, the scheduled real power and reactive powers, and the reactances of transmission lines are marked at this one line diagram (The voltages and reactances are in PU referred to 100 MW base. The active power P2 in MW is the last three digits (from right) of your registration number (i.e for the student that has a registration number 202112396, P2 =396). [10] Starting from an estimated voltage at bus 2, bus 3, and bus 4 equals V2 (0) = 1.15<0°, V3 = 1.15 < 0°, V4 1.1< 0°. 1- Specify the type of each bus and known & unknown quantities at each bus. 2- Find the elements of the second row of the admittance matrix (i.e. [Y21 Y22 Y23 Y24]). 3- Using Gauss-Siedal fınd the voltage at bus 2 after the first iteration. 4- Using Newton-Raphson, calculate: |- The value of real power (P2), at bus 2 after the first iteration. Il- The second element in the first row of the Jacobian matrix after the first iteration. 2 P2…
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
Figure below shows a power system where load at bus 5 is fed by generators at bus 1 and bus 4. The generators are rated at 100MVA; 11 KV with subtransient reactance of 25%. The transformers are rated each at 100 MVA, 11/112 KV and have a leakage reactance of 8%. The lines have an inductance of 1 mH/phase/km. Line L1 is 100 km long while lines L2 and L3 are each of 50 km in length. He Load 10 For a 3-phase fault at bus 5, the fault current is equal to 2530A. What the value of the change in the fault current if the length of L1 is reduced to 50 km (i.e. new .value/old value) 1 O 1.0174 0.9965 1.0062 1.0222 0.9867