Critical Clearing Angle example P. 0.8 p.u. q- 0.074 p.u. connected to infinite bus of 1.0 p.u. A Three phase fault on any of the transmission feeder lines; Determine the critical clearing angle. What is the critical clearing angle - The critical clearing angle is the angle through which a generator rotor must be displaced from its equilibrium position following a disturbance (such as a fault) to just maintain stability in a power system. In other words, it is the maximum angle by which the rotor of a synchronous machine can be swung following a disturbance and still allow the system to reach a stable post-fault condition. Xt = 0.2 E' OBE X=0.3 1 V₁=1.1 XL1=0.3 XL2=0.3 The current flowing into the infinite bus is S* V* 1== 0.8-j0.074 1.020° = 0.8-j0.074p.. B The transfer reactance between internal voltage and the infinite bus before fault is: 2 V 1.020 8

Critical Clearing Angle example P. 0.8 p.u. q- 0.074 p.u. connected to infinite bus of 1.0 p.u. A Three phase fault on any of the transmission feeder lines; Determine the critical clearing angle. What is the critical clearing angle - The critical clearing angle is the angle through which a generator rotor must be displaced from its equilibrium position following a disturbance (such as a fault) to just maintain stability in a power system. In other words, it is the maximum angle by which the rotor of a synchronous machine can be swung following a disturbance and still allow the system to reach a stable post-fault condition. Xt = 0.2 E' OBE X=0.3 1 V₁=1.1 XL1=0.3 XL2=0.3 The current flowing into the infinite bus is S* V* 1== 0.8-j0.074 1.020° = 0.8-j0.074p.. B The transfer reactance between internal voltage and the infinite bus before fault is: 2 V 1.020 8

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 9.13P: Consider the oneline diagram of a simple power system shown in Figure 9.20. System data in per-unit...

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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.
Consider the oneline diagram of a simple power system shown in Figure 9.20. System data in per-unit on a 100-MVA base are given as follows: The neutral of each generator is grounded through a current-limiting reactor of 0.08333 per unit on a 100-MVA base. All transformer neutrals are solidly grounded. The generators are operating no-load at their rated voltages and rated frequency with their ENIFs in phase. Determine the fault current for a balanced three-phase fault at bus 3 through a fault impedance ZF=0.1 per unit on a 100-MVA base. Neglect -Y phase shifts.
With the same transformer banks as in Problem 3.47, Figure 3.41 shows the oneline diagram of a generator, a step-up transformer bank, a transmission line, a stepown transformer bank, and an impedan load. The generator terminal voltage is 15 kV (line-to-line). (a) Draw the per-phase equivalent circuit, aounting for phase shifts for positive-sequence operation. (b) By choosing the line-to-neutral generator terminal voltage as the reference, determine the magnitudes of the generator current, transmiss ion-line current, load current, and line-to-line load voltage. Also, find the three-phase complex power delivered to the load.
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. A 3 phase fault occurs at point F as shown in figure. Determine the critical clearing anglefor the system. The generator is delivering 1.0 p.u power under prefault conditio
A star connected neutral grounded 3-phase synchronous generator consists of 0.1 p.u of sub transient reactance ,0.3 p.u of transient reactance and 0.5 p.u of leakage reactance.The zero sequence reactance of the synchronous reactance is None of the above 0.5 p.u 0.7 p.u 0.6 p.u
02. The 3-p generator is rated 20 MVA, 13.8 kV. The positive, negative & zero sequence reactances are respectively 0.25, 0.35 & 0.10 pu. The neutral of generator is grounded with reactance of 0.15 pu. Determine the sub-transient current & line to line voltages of the generator when a grievous fault occurs among the unsymmetrical faults at the generator terminals with the generator operating unloaded at rated voltage. Consider generator armature resistance is 0.2 Ω.
A 25 MVA, II kV generator has X"d=0.2 p.u. X2 = 0.3p.u. and X0=0.1 p.u. Tht neutral of generator is solidly grounded. Determine the subtransient current in the generator and the line to line voltages for subtransient condition when a Y-B-G fault occurs at the generator terminals. Assume prefault currents and fault resistance to be zero.
b) A fault occurs at bus 3 of the network shown in Figure Q4. Pre-fault nodal voltages throughout the network are of 1 p.u. and the impedance of the electric arc is neglected. Sequence impedance parameters of the generator, transmission lines, transformer and load are given in Figure Q4. V₁ = 120° p.u. V₂ = 120° p.u. V₂ = 1/0° p.u. V₂= 120° p.u. jXj0.1 p.u. JX2) 0.1 p.u. jX0j0.15 p.u. jXn-j0.2 p.u. 1 JX(2)-j0.2 p.u. 2 jX)=j0.25 p.u. JX20-10.15 p.u. jXa(z)-j0.2 p.u. 4 jX2(0)=j0.2 p.u. jXT(1) j0.1 p.u. jXT(2)=j0.15 p.u. jXT(0)=j0.1 p.u. Figure Q4. Circuit for problem 4b). = jXj0.1 p.u. j0.1 p.u. - JX(2) JXL(0) 10.1 p.u. = (i) Assuming a balanced excitation, draw the positive, negative and zero sequence Thévenin equivalent circuits as seen from bus 3. (ii) Determine the positive sequence fault current for the case when a three- phase-to-ground fault occurs at bus 3 of the network. (iii) Determine the short-circuit fault current for the case when a one-phase- to-ground fault occurs at bus…
b) A fault occurs at bus 4 of the network shown in Figure Q3. Pre-fault nodal voltages throughout the network are of 1 p.u. and the impedance of the electric arc is neglected. Sequence impedance parameters of the generator, transmission lines, and transformer are given in Figure Q3, where X and Y are the last two digits of your student number. jX(1) j0.1Y p.u. jX2)= j0.1Y p.u. jXko) = j0.1X p.u. V₁ = 120° p.u. V₂ = 120° p.u. (i) (ii) 0 jX(1) = j0.2 p.u. 1 jx(2) j0.2 p.u. 2 jX1(0) = j0.25 p.u. jXT(1) jXT(2) 종 3 j0.1X p.u. JX3(1) j0.1Y p.u. j0.1X p.u. JX3(2) j0.1Y p.u. jXT(0) j0.1X p.u. JX3(0)=j0.15 p.u. 0 = x = 1, jX2(1) j0.2Y p.u. V₁=1/0° p.u. jX(2(2) = j0.2Y p.u. jX2(0) = j0.3X p.u. = V3 = 120° p.u. Figure Q3. Circuit for problem 3b). For example, if your student number is c1700123, then: y = 7 = = jXa(r) = j0.13 p.u., jXa(z) = j0.13 p. u., and jXa(o) = j0.12 p. u. Assuming a balanced excitation, draw the positive, negative and zero sequence Thévenin equivalent circuits as seen from…
13. A generator rated 30 MVA, 11 kV has a direct-axis subtransient reactance of 0.3 p.u. the negative and zero sequence reactances are 0.45 and 0.15 p.u. respectively. The neutral is solidly grounded. Determine the subtransient current in the generator when a line to ground fault occurs at the terminals of the generator with the generator running on no load at rated voltage. Ignore resistance. (
Q-5-) 60 Hz generator supplies 0.50 Pmax power to a busbar with infinite power over a conveying line. When a fault occurs, the reactance value between the generator and the infinite bus becomes 400% times the value before the fault. When the fault is isolated, the maximum power that can be transferred generator to the endless bus is 75% of the original (initial) maximum value. Accordingly, using t area criterion method, calculate the critical clearance angle of the system. 00