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.

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.

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 3.37P: Three single-phase two-winding transformers, each rated 25MVA,54.2/5.42kV, are connected to form a...

See similar textbooks

Similar questions

Determine the positive- and negative-sequence phase shifts for the three- phase transformers shown in Figure 3.36.
Three single-phase two-winding transformers, each rated 25MVA,54.2/5.42kV, are connected to form a three-phase Y- bank with a balanced Y-connected resistive load of 0.6 per phase on the low-voltage side. By choosing a base of 75 MVA (three phase) and 94 kV (line-to-line) for the high-voltage side of the transformer bank, specify the base quantities for the low-voltage side. Determine the per-unit resistance of the load on the base for the low-voltage side. Then determine the load resistance RL in ohms referred to the high-voltage side and the per-unit value of this load resistance on the chosen base.
Q2. The single-line diagram of a simple three-bus power system is shown in Figure-2. Each generator is represented by an emf behind the sub-transient reactance. All impedances are expressed in per unit on a common MVA base. All resistances and shunt capacitances are neglected. The generators are operating on no load at their rated voltage with their emfs in phase. A three-phase fault occurs at bus 3 through a fault impedance of Zf = j0.19 per unit. (i) Using Th'evenin's theorem, obtain the impedance to the point of fault and the fault current in (ii) Determine the bus voltages per unit. ) j0.05 j0.075 j0.75 2 j0.30 j0.45 Figure-2: Single line diagram of the power system network for Q2 3
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.
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
In large transformers, the total copper losses may vary from the rated output. % of 0.8 to 1.5 0.2 to 0.6 0.5 to 1 0.4 to 1
QUESTION #2: A 50 MVA, 11 kV, 3 phase alternator has a direct subtransient reactances of 0.1 pu. The negative and zero sequences reactances are 0.15 and 0.25 pu respectively. The neutral of the generator is solidly earthed. Determine the subtransient current in the generator and the line to line voltages for subtransient conditions when a single line to ground fault occurs at the generator terminals with the generator operating unloaded at rated voltage.
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. (
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…
Description In the particular case of figure below derive both the critical clearing angle and the critical clearing time. P, = Pmaz sin d Pm A1 do der Smar A generator having H = 6.R MJ/MVA is delivering power of 1.0 per unit to an infinite bus through a purely reactive network when the occurrence of a fault reduces the generator output power to zero. The maximum power that could be delivered is 2.5S per unit. When the fault is cleared, the original network conditions again exist. Determine the critical clearing angle and critical clearing time. (Roll=PQRS)
FIGURE Q2 shows a four bus three phase power system. The generators, transformers and transmission line per unit reactance are given as follows: Generator G1, G2: XG= 0.05 pu Transformers T1, T2: XT= 0.13 pu Transmission Line 2 – 3: XL = 0.50 pu Bus 1 Bus 2 Bus 3 Bus 4 Line GI T1 G2 FAULT FIGURE Q2 Evaluate the per unit fault current, fault MVA and voltage at all buses if a three phase bolted fault occurs at Bus 2.
A 30 MVA, 11 kV generator has a reactance of 0.10p.u.on its own base. Determine the per-unit reactance when referred to base kVA of 50,000 kVA and base kV of 33 kV.