Power System Analysis and Design (MindTap Course List)
6th Edition
ISBN: 9781305632134
Author: J. Duncan Glover, Thomas Overbye, Mulukutla S. Sarma
Publisher: Cengage Learning
expand_more
expand_more
format_list_bulleted
Concept explainers
Videos
Textbook Question
Chapter 7, Problem 7.3MCQ
The amplitude of the sinusoidal symmetrical ac component of the three-phase short-circuit current of an unloaded synchronous machine decreases from a high initial value to a lower steady-state value, going periods through the stages of __________ and ________ periods.
Expert Solution & Answer
Want to see the full answer?
Check out a sample textbook solution
Students have asked these similar questions
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
Figure shows a generator connected to a metropolitan system (infinite bus) through highvoltage lines. The numbers on the figure indicate the reactances in p.u. Breakers adjacent to afault on both sides are arranged to clear simultaneously. Determine the critical clearing anglefor the generator for a 3-phase fault at the point P when the generator is delivering 1.0 p.u.power. Assume that the voltage behind transient reactance is 1.2 p.u. for the generator andthat the voltage at the infinite bus is 1.0 p.u.
The __________________ condition of the power system gives the power flow solutions when the transient behavior of the system is to be studied.
a-Initial
b-Short Circuit
c-Stability
d-Transient
Chapter 7 Solutions
Power System Analysis and Design (MindTap Course List)
Ch. 7 - Even though the fault current is not symmetrical...Ch. 7 - The amplitude of the sinusoidal symmetrical ac...Ch. 7 - Equipment ratings for the four-bus power system...Ch. 7 - Equipment ratings for the five-bus power system...Ch. 7 - Prob. 7.22PCh. 7 - A three-phase circuit breaker has a 15.5-kV rated...Ch. 7 - Prob. 7.32P
Knowledge Booster
Learn more about
Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, electrical-engineering and related others by exploring similar questions and additional content below.Similar questions
- 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arrow_forwardQ6. Q7. Q8. Q9. When identical partially loaded AC generating units are operating in parallel on governor control, and one generator (G1) has a 5 % governor droop and the other generator (G2) has a 10% governor droop, if the load increased by 60MW each generator will increase its output by (a) (b) (d) Which of the following governor controlled, grid connected generating units will produce the largest change in power output for a 0.1 Hz drop in grid frequency? (a) පිම 0 MW and 60 MW 20 MW and 40 MW 30 MW and 30 MW 40 MW and 20 MW 60 MW and 0 MW TOOTE Which of the following device/method provides primary frequency response following a disturbance in a large, interconnected power system? 1% 4% 5% 25% 100% TOOTE Free governor action Isochronous Unit Automatic Voltage Control Operator Dispatch Automatic Generation Control Which of the following device/method is used to restore a system frequency to rated following a disturbance in a large, interconnected power system? Free governor action…arrow_forwardThe effective resistance of a 2200 V, 50 Hz, 440 KVA, 1 -phase alternator is 0.5 ohm. On short-circuit, a field current of 40 A gives the full load current of 200 AS. The electromotive force on open-circuits with same field excitation is 1160 V. Then the synchronous impedance and reactance is _______ ohm and _______ ohm respectively.arrow_forward
- A 15,000 KVA, 6.9 KV generator, star connected has positive, negative and zero sequence reactances of 0.25, 0.25 and 0.08 p.u. respectively. A reactor of 0.06 p.u. reactance on the generator rating is placed in the line from neutral to ground: A double line to ground fault occurs at the terminals of the generator when it is operating at its rated voltage and unloaded. Find the unitial r.m.s. line and ground wire current for a solidly grounded fault, and also the voltage to ground of the unfaulted line. (UPSC-1975) Ans: 1-1,-4970 A; I, 5480 A; V. 69.7 KVarrow_forwardThe figure shows the single line diagram of a single machine infinite bus system. O Infinite bus The inertia constant of the synchronous generator H = 5 MW-s / MVA. Frequency is 50 Hz. Mechanical power is 1 pu. The system is operating at the stable equilibrium point with rotor angle ō equal to 30°. A three phase short circuit fault occurs at a certain location on one of the circuits of the double circuit transmission line. During fault, electrical power in pu is Pmax sin ō. If the values of ō and do / dt at the instant of fault clearing are 45° and 3.762 radian/s respectively, then Pmax (in pu) is_arrow_forwardQ2:- a synchronous generator is 25 MVA, 11kV, it is star- connected with the neutral point solidly grounded the generator is operating at no load rated voltage. Its reactances are X₁ = X₂ = 0.2 and Xo = 0.08 pu, calculate : a) The symmetrical sub transient line currents for SLG, LL, LLG and symmetrical three phase current. b) The value of reactance to be included in the generator neutral and grounded, so that line to ground fault current equals to the three phase fault current what will be the value of ground resistance to achieve the same condition ? c) With reactance value calculated in (b) included between neutral and ground. Calculate the line to line current and double line to ground fault current.arrow_forward
- Q2. Figure Q2 shows a 300 MW, 50 Hz generator transmitting 280 MW real power to an infinite bus through double transmission lines. A three-phase fault occurs at point P in the middle of one of the transmission lines. (i) Write the generator output power-angle equation per unit for pre-fault, during fault and post-fault conditions. (ii) Determine the critical clearing angle using equal criteria method E=1.05 p.u X'=j0.12 p.u X=j0.17 p.u @ Figure Q2 Xime=j0.6 p." Xime=j0.6 p.u P * V=1.0 p.uarrow_forwardA three-phase, 100-MVA, 20-kV generator is connected to a three-phase, 100-MVA, 20-kV motor through a transmission line. The reactances of the generator and motor are 0.25 and 0.20 per unit, respectively. The line reactance is 0.10 per unit. The motor is taking 50 [MW] at 0.8 power factor leading at rated voltage. Suppose a three-phase short circuit occurs at the generator terminals, determine the transient currents in the generator and motor as well as the short-circuit current.arrow_forwardQ6/A 3-phase, 50Hz synchronous generator having H=6 MJ/MVA is delivering power of 1.0 P.U to infinite bus through a network as shown in Figure (5). If a three-phase fault occurs at point F, determine the critical clearing angle of the mentioned fault. Bus-1 Bus-2 ZT.L-j0.4 pu E1=1.2 pu E2=1.0 pu ZT.L=j0.4 pu X=0.2 pu Figure (5) 10 -0arrow_forward
- -The sum of the armature reactance and.............reactance is the reactance of the synchronous generator after the short circuit fault is cleared. -The selection of number of generating sources to meet the expected load is called as economic dispatch. Select one: True Falsearrow_forwardb) Two synchronous generators, G2 and G2, are connected parallelly supplying a load. Generator G1 has a no-load frequency of 50.5 Hz and a slope of 300 MW/Hz. Generator G2 has a no-load frequency of 50.2 Hz and a slope of 500 MW/Hz. The load consumes 250 MW real power. (1) At what frequency does this system operate, and how much power is supplied by each of the two generators? (ii) An additional 100 MW load is added to this power system. What is the new system frequency, and how much power do G1 and G2 supply? (iii) The governor set point of G2 is changed to control system frequency back to 50 Hz. Determine the G2 governor set point.arrow_forwardb) 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…arrow_forward
arrow_back_ios
SEE MORE QUESTIONS
arrow_forward_ios
Recommended textbooks for you
Power System Analysis and Design (MindTap Course ...Electrical EngineeringISBN:9781305632134Author:J. Duncan Glover, Thomas Overbye, Mulukutla S. SarmaPublisher:Cengage Learning
Power System Analysis and Design (MindTap Course ...
Electrical Engineering
ISBN:9781305632134
Author:J. Duncan Glover, Thomas Overbye, Mulukutla S. Sarma
Publisher:Cengage Learning
How does an Alternator Work ?; Author: Lesics;https://www.youtube.com/watch?v=tiKH48EMgKE;License: Standard Youtube License