***Line Impedance between T4 and T5 is j25, not j2*** 3.41 Consider the single-line diagram of the power system shown inFigure 3.38. Equipment ratings areGenerator 1:1000 MVA, 18 kV, X" =0.2 per unitGenerator 2:1000 MVA, 18 kV, X" = 0.2 p.u.Synchronous motor 3:1500 MVA, 20 kV, X" = 0.2 p.u.Three-phase A-Y transformersT1,T3, T3, Tạ:1000 MVA, 500 kV Y/20 kV A,X = 0.1 p.u.Three-phase Y-Y transformer T3: 1500 MVA, 500 kV Y/20 kV Y,X = 0.1 p.u.Neglecting resistance, transformer phase shift, and magnetizing reac-tance, draw the equivalent reactance diagram. Use a base of 100 MVAand 500 kV for the 50-ohm line. Determine the per-unit reactances.FIGURE 3.382Problems 3.41j 50 Nand 3.42T2T4T3| 25 2T53)

3.41 Consider the single-line diagram of the power system shown in Figure 3.38. Equipment ratings are Generator 1: 1000 MVA, 18 kV, X" = 0.2 per unit Generator 2: 1000 MVA, 18 kV, X" = 0.2 p.u. Synchronous motor 3: 1500 MVA, 20 kV, X" = 0.2 p.u. Three-phase A-Y transformers T,T, T, T;: 1000 MVA, 500 kV Y/20 kV A, X = 0.1 p.u. Three-phase Y-Y transformer T;: 1500 MVA, 500 kV Y/20 kV Y, X = 0.1 p.u. Neglecting resistance, transformer phase shift, and magnetizing reac- tance, draw the equivalent reactance diagram. Use a base of 100 MVA and 500 kV for the 50-ohm line. Determine the per-unit reactances.

3.41 Consider the single-line diagram of the power system shown in Figure 3.38. Equipment ratings are Generator 1: 1000 MVA, 18 kV, X" = 0.2 per unit Generator 2: 1000 MVA, 18 kV, X" = 0.2 p.u. Synchronous motor 3: 1500 MVA, 20 kV, X" = 0.2 p.u. Three-phase A-Y transformers T,T, T, T;: 1000 MVA, 500 kV Y/20 kV A, X = 0.1 p.u. Three-phase Y-Y transformer T;: 1500 MVA, 500 kV Y/20 kV Y, X = 0.1 p.u. Neglecting resistance, transformer phase shift, and magnetizing reac- tance, draw the equivalent reactance diagram. Use a base of 100 MVA and 500 kV for the 50-ohm line. Determine the per-unit reactances.

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 3.41P: Consider the single-line diagram of the power system shown in Figure 3.38. Equipment ratings are...

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Consider the single-line diagram of the power system shown in Figure 3.38. Equipment ratings are Generator 1: 1000MVA,18kV,X=0.2perunit Generator 2: 1000MVA,18kV,X=0.2p.u. Synchronous motor 3: 1500MVA,20kV,X=0.2p.u. Three-phase -Y transformers T1,T2,T3,T4,: 1000MVA,500kV,Y/20kV,X=0.1p.u. Three-phase YY transformer T5: 1500MVA,500kV,Y/20kVY,X=0.1p.u. Neglecting resistance, transformer phase shift, and magnetizing reactance, draw the equivalent reactance diagram. Use a base of 100 MA and 500 kV for the 50-ohm line. Determine the per-unit reactances.
Consider a single-phase electric system shown in Figure 3.33. Transformers are rated as follows: XY15MVA,13.8/138kV, leakage reactance 10 YZ15MVA,138/69kV, leakage reactance 8 With the base in circuit Y chosen as 15MVA,138kV determine the per-unit impedance of the 500 resistive load in circuit Z, referred to circuits Z, Y, and X. Neglecting magnetizing currents, transformer resistances, and line impedances, draw the impedance diagram in per unit.
Figure 3.39 shows a oneline diagram of a system in which the three-phase generator is rated 300 MVA, 20 kV with a subtransient reactance of 0.2 per unit and with its neutral grounded through a 0.4- reactor. The transmission line is 64km long with a cries reactance of 0.5-/km. The three-phase transformer T1 is rated 350MVA.230/20kV with a leakage reactance of 0.1 per unit. Transformer T2 is composed of three single-phase transformers, each rated 100 MVA, 127/13.2kV with a leakage reactance of 0.1 per unit. Two 13.2kV motors M1 and M2 with a subtransient reactance of 0.2 per unit for each motor represent the load. M1 has a rated input of 200 MVA with its neutral grounded through a 0.4- current-limiting reactor, M2 has a rated input of 100 MVA with its neutral not connected to ground. Neglect phase shifts associated with the transformers. Choose the generator rating as base in the generator circuit and draw the positive-sequence reactance diagram showing all reactances in per unit.
PowerWorid Simulator case Problem 3_60 duplicates Example 3.13 except that a resistance term of 0.06 per unit has been added to the transformer and 0.05 per unit to the transmission line. Since the system is no longer lossless, a field showing the real power losses has also been added to the oneline. With the LTC tap fixed at 1.05, plot the real power losses as the phase shift angle is varied from 10 to +10 degrees. What value of phase shift minimizes the system losses?
Consider the oneline diagram shown in Figure 3.40. The three-phase transformer bank is made up of three identical single-phase transformers, each specified by X1=0.24 (on the low-voltage side), negligible resistance and magnetizing current, and turns ratio =N2/N1=10. The transformer bank is delivering 100 MW at 0.8 p.f. lagging to a substation bus whose voltage is 230 kV. (a) Determine the primary current magnitude, primary voltage (line-to-line) magnitude, and the three-phase complex power supplied by the generator. Choose the line-to-neutral voltage at the bus, Va as the reference Account for the phase shift, and assume positive-sequence operation. (b) Find the phase shift between the primary and secondary voltages.
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.
An infinite bus, which is a constant voltage source, is connected to the primary of the three-winding transformer of Problem 3.53. A 7.5-MVA,13.2-kV synchronous motor with a sub transient reactance of 0.2 per unit is connected to the transformer secondary. A5-MW,2.3-kV three-phase resistive load is connected to the tertiary Choosing a base of 66 kV and 15 MVA in the primary, draw the impedance diagram of the system showing per-unit impedances. Neglect transformer exciting current, phase shifts, and all resistances except the resistive load.
Figure 3.32 shows the oneline diagram of a three-phase power system. By selecting a common base of 100 MVA and 22 kV on the generator side, draw an impedance diagram showing all impedances including the load impedance in per-unit. The data are given a follows: G:90MVA22kVx=0.18perunitT1:50MVA22/220kVx=0.10perunitT2:40MVA220/11kVx=0.06perunitT3:40MVA22/110kVx=0.064perunitT4:40MVA110/11kVx=0.08perunitM:66.5MVA10.45kVx=0.185perunit Lines I and 2 have series reactances of 48.4 and 65.43, respectively. At bus 4, the three-phase load absorbs 57 MVA at 10.45 kV and 0.6 power factor lagging.
Q4 / Equipment ratings for the four - bus power system shown in Figure are given as follows: TI 73 60 500 Generator GI: 500 MVA, 13.8 KV. X = X2 = 0.20. Xo = 0.10 per unit Generator G2: 750 MVA, 18 KV.X = X2 = 0.18, Xo = 0,09 per unit Generator G3: 1000 MVA, 20 kV, X = 0.17. Xz = 0.20.Xo = 0.09 per unit Transformer Ti: 500 MVA, 13.8 kV A / S00 kV Y. X = 0.12 per unit Transformer T2: 750 MVA, 18 LV A / 500 kV Y, X = 0.10 per unit Transformer T3: 1000 MVA, 20 kV A / 500 kV Y. X = 0.10 per unit each line: X = 50 ohms, X, = 150 ohms 77 The inductor connected to generator G3 neutral has a reactance of 0.028 pu. Draw the zero-, positive-, and negative - sequence reactance diagrams using a 1000 - MVA, 20 - KV base in the zone of generator G3
Refer to the 5-bus data given below. Sbase = 400 MVA, the base voltage is 15.0 kV for buses 1 and 3, and 345 kV for buses 2, 4, 5. Note that 1-5 and 3-4 are 15/345 kV transformers.a) Draw a one-line diagram of the power system.b) Find the elements Y23, Y43, Y11 Y33 of the system bus admittance matrix.
In a 3-phase overhead system, each line is suspended by a string of 3 insulators. The voltage across the top unit (i.e. near the tower) and middle unit are 10 kV and 11 kV respectively. Calculate (i) the ratio of shunt capacitance to self capacitance of each insulator, (ii) the string efficiency and (iii) line voltage
What is the per unit impedance of a 50 MVA, 13.8 kV, 1% impedance transformer if the base is change to 100 MVA, 6.9 kV? Answer: 8% Use the formula: Zpu=(Srated)(Zo1)/E²