The synchronous generator in Figure 2 is operating at rated MVA and at . PU 5% above rated voltage when a bolted three-phase short circuit occurs at bus 1. (1)Draw the equivalent circuit of Figure 2;(2)Calculate subtransient fault current, subtransient generator and motor currents, neglecting prefault current (including per unit value and real value). ( T1 T2 bus2 bus 1 100MVA L +0+ ++ 10kV X=0.20 X=0.15 100MVA (base on 100MVA 10.5kV), 100MVA 10.5kV 100MVA 110kV/10.5kV 10.5kV/121kV 100MVA 10kV X=0.15 X=0.10 X=0.10 X=0.20 Figure 2 M M

The synchronous generator in Figure 2 is operating at rated MVA and at . PU 5% above rated voltage when a bolted three-phase short circuit occurs at bus 1. (1)Draw the equivalent circuit of Figure 2;(2)Calculate subtransient fault current, subtransient generator and motor currents, neglecting prefault current (including per unit value and real value). ( T1 T2 bus2 bus 1 100MVA L +0+ ++ 10kV X=0.20 X=0.15 100MVA (base on 100MVA 10.5kV), 100MVA 10.5kV 100MVA 110kV/10.5kV 10.5kV/121kV 100MVA 10kV X=0.15 X=0.10 X=0.10 X=0.20 Figure 2 M M

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

Chapter7: Symmetrical Faults

Section: Chapter Questions

Problem 7.14P: Equipment ratings for the five-bus power system shown in Figure 7.15 are as follows: Generator G1:Â...

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As shown in Figure 1, a synchronous generator and motor are rated 100 MVA, 13.8 kV.??"=0.2per unit, ??"=0.15per unit, and ??=0.305per unit. The synchronous generator is operating at 100 MVA, 0.95 p.f. lagging and at 1.05 per unit voltage when a three-phase short circuit occurs atbus 2. Please use the direct method to calculate the per-unit values of (a)subtransient generator current (??"); (b)subtransient motor current (??"); and (c)subtransient fault current (??). Please use the superposition method to calculate the per-unit values of (d)subtransient generator current (??"); (e)subtransient motor current (??"); and (f)subtransient fault current (??).
The armature resistance and synchronous reactance of a 2 MVA, 11 KV, 3-phase star connected synchronous generator are 2 ohms and 20 ohms per phase respectively. How many volts per phase full load voltage for unit power factor?
Three-phase, 60-Hz synchronous generator is connected through a transformer and paralleltransmission lines to an infinite bus. All reactances are given in per-unit on a common systembase. If the infinite bus receives 1.0 per unit real power at 0.95 p.f. lagging, determinea) the internal voltage of the generator andb) the equation for the electrical power delivered by the generator versus its power angle δ.
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.
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.
A single line diagram of a power system is shown in Figure Q2.1. The neutrals for the generators and transformers are solidly grounded. The motor neutral is grounded through reactance ?? = 0.05 per unit on the motor base. i）Calculate the phase currents in kA following a three-phase fault at busbar 2. ii) Calculate the phase currents in kA when a phase-alpha-to-ground fault occurs at busbar 2.
Discuss system demand and generator loading
A three-phase, 250 MVA, 16 kV rated synchronous generator is feeding into an infinite bus bar at 15 kV. The generator has a synchronous reactance of 1.62 pu. It is found that the machine excitation and mechanical power input are adjusted to give E = 24 kV and power angle δ = 30◦. a) Determine the line current and active and reactive power fed to the generator terminal. b) With reference to part (a) current is to be reduced by 20% at the same power factor by adjusting mechanical power input to the generator and its excitation. Determine E, angle δ and mechanical power input. c) With the reduced current as in part (c), the power is to be delivered to generator terminal at unity power factor, what are the corresponding values of E and δ and also the mechanical power input to the generator. Per-unit values are given on machine rating as the base.
A 24,000 kVA, 17.32 kV, three-phase, 60 Hz synchronous reactance of 5 Ω/phase and negligible armature resistance. At a certain excitation, the generator delivers rated load, 0.8 pf lagging to an infinite bus bar at a line the line voltage of 17.32 kV. Determine the excitation voltage per phase
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