2-) The per-unit bus impedance matrix for the power system shown below is given by Ꮓ bus [j0.150 j0.075 0.140 0.135] j0.075 j0.1875 j0.090 j0.0975 j0.140 j0.090 j0.2533 j0.210 j0.135 j0.0975 j0.210 j0.2475] The generator internal emfs and reactances are Gl: E1.20 p.u., X₁ =j0.2 p.u. G2: E₁ = 1.25/0 p.u., X₁₂ = j0.3 p.u. An impedance Z = 0.1+ j0.2 is connected between buses 3 and 4. (a) Calculate the new bus impedance matrix Z (new) bus (b) Determine the new bus voltages at all the buses. (c) Calculate the current in Z. 1 G1 G2 2 j0.2 3 j0.3 j0.5 j0.1 j0.6 +

2-) The per-unit bus impedance matrix for the power system shown below is given by Ꮓ bus [j0.150 j0.075 0.140 0.135] j0.075 j0.1875 j0.090 j0.0975 j0.140 j0.090 j0.2533 j0.210 j0.135 j0.0975 j0.210 j0.2475] The generator internal emfs and reactances are Gl: E1.20 p.u., X₁ =j0.2 p.u. G2: E₁ = 1.25/0 p.u., X₁₂ = j0.3 p.u. An impedance Z = 0.1+ j0.2 is connected between buses 3 and 4. (a) Calculate the new bus impedance matrix Z (new) bus (b) Determine the new bus voltages at all the buses. (c) Calculate the current in Z. 1 G1 G2 2 j0.2 3 j0.3 j0.5 j0.1 j0.6 +

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

Chapter3: Power Transformers

Section: Chapter Questions

Problem 3.40P

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The per unit bus impedance matrix for the power system network of Figure Q1 is given by; r0.240 0.140 0.200 0.2001 Zbus = i0.140 0.2275 0.175 0.175 0.200 0.175 0.310 0.310 Lo.200 0.175 0.310 0.500 j0.20 j0.15 j0.20 j0.20 j0.50 j0.20 j0.30 3 j0.19 Figure Q1 Evaluate the fault current, bus voltages and line currents during fault, when fault occurs at bus 2 with Z: = j0.0225.
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.
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
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
The per unit equivalent system of a power system is shown below. It is working at no load when a symmetrical 3 phase fault is developed on bus 3. Suppose also that the no-load voltage at every bus is equal to the pre-fault voltage: Vf 1.000 pu and the inverse of this matrix is given below 4 140° Z j0.1 m j0.1 a. None b. V3-0 c. V3-0.30 d. V3-0.32 j0.2 m [0+ j0.1799 0+j0.1636 0+j0.1743 0+j0.1753] 0+j0.1636 0+jo.3591 0+j0.1929 0+30.2194 0+j0.1743 0+j0.1929 0+j0.2565 0+j0.1796 Lo+jo.1753 0+jo.2194 0+j0.1796 0+j0.3307 The per-unit voltage at bus 3 in the system during the sub transient period is: Select one: j0.1 m j0.8 mm j0.5 3 j0.5 mor 2 j2.5 m vvvv N
Q6/ The per-unit reactance for a given system are shown in figure below. (1 MVA) is being delivered to the receiving end bus of the system at unity power factor and unit voltage. A three phase short circuit occurs at F. Find the critical clearing angle and the critical clearing time? Take H = 3 p. u. second tc X=j0.3 j0.1 w Peralat j0.25 j0.25 V20 x 1
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 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

The one line diagram of a simple 3-bus power system shown below. All impedances are expresses in per unit on a common base. A three phase fault occurs at bus 3 through a fault impedance Z =j 0.19 pu, calculate the per unit fault current. A. 1.5 p.u. B.2.5 p.u. G₁ j 0.05 j0.75 j 0.3 3 C. 5.0 p.u. D. 3.0 p.u. G₂ j 0.075 j0.45 2
Busl UIN: Bus2 Bus3 Figure 1: One line diagram All impedances are specified in per unit. For generators, assume Z' = Z =j0.2, z° = j0.05 For transformers, assume Z*= Z =Z° = j0.05 For lines assume Z* = Z =j0.1, z° = j0.3 Assume unloaded pre-fault condition with voltages = 1.0 pu at all the three buses. A fault occurs at bus a1 Ignore phase shift and perform the following computations: Draw the sequence network diagrams (positive, negative and zero) and find the Thevenin equivalent for each sequence network at bus 1 where the fault occurs.
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.