Power System Analysis and Design (MindTap Course List)
6th Edition
ISBN: 9781305632134
Author: J. Duncan Glover, Thomas Overbye, Mulukutla S. Sarma
Publisher: Cengage Learning
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Chapter 9, Problem 9.34P
At the general three-phase bus shown in Figure 9.7(a) of the text, consider a simultaneous single line-to-ground fault on phase a and line-to-line fault between phases b and c, with no fault impedances. Obtain the sequence-network interconnection satisfying the current and voltage constraints.
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sequence networks are to be connected
fault terminals through the impedance
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For a line-to-line fault with a fault impedance ZF, the positive and
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; the positive and negative sequence components of the fault
current are
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For a double-line-to-ground fault with a fault impedance ZF, the
sequence networks are to be connected
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Consider the system shown in the single-line diagram of Figure (3). All reactances are shown in per
unit to the same base. Assume that the voltage at both sources is 1 p.u.
a Find the fault current due to a bolted- three-phase short circuit at bus 3
b- Find the fault current supplied by each generator and the voltage at each of the buses 1 and 2
under fault conditions
0.06 p.u.
0.2 p.u.
0.04 p.u.
0.25 p.u.
0.2 p.u.
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0.06 p.u.
0.25 p.u.
Figure (3) Single-line diagram
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Consider the single-line diagram of a power system shown below. The transient reactance of cach part of the system is as shown in table and expressed in p.u. on a common 100 MVA base. A three-phase fault with impedance of 0.16 p. occurs at bus (5). Determine short- circuit capacity (fault level) and short circuit current? Assume the fault voltage at bus (5) equal 112 KV
Chapter 9 Solutions
Power System Analysis and Design (MindTap Course List)
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- For the system of Problem 9.13, compute the fault current for the following faults at bus 3: (a) a single line-to-ground fault through a fault impedance ZF=j0.1 per unit, (b) a line-to-line fault through a fault impedance ZF=j0.1 per unit, (c) a double line-to-ground fault through a common fault impedance to ground ZF=j0.1 per unit.arrow_forwardb) A fault occurs at bus 4 of the network shown in Figure Q3. Pre-fault nodal voltages throughout the network are of 1 + j0 p.u, and the impedance of the electric arc is neglected (Zf = 0 + j0 p.u.). The positive, negative and zero sequence impedance parameters of the generator, transmission lines and transformer are given in Figure Q3. (i) Determine the positive sequence fault current for the case when a three-phase-to-ground fault occurs at bus 4 of the network (ii) Determine the short-circuit fault current for the case when a one-phase- to-ground fault occurs at bus 4. Recall that phasors can be expressed in terms of their symmetrical components as shown in the picture attached. where F stands for any three-phase quantity (e.g., current, voltage) (iii) Determine the short-circuit fault current for the case when a phase-to-phase fault occurs at bus 4 ReplyForwardarrow_forwardA single-line diagram of the power system is shown in Figure 2, where negative- and zero-sequence reactances are also given. (a) Draw the per-unit zero-, positive-, and negative sequence networks. (b) For a fault at bus 7 find the sequence Thevenin equivalents. (c) Calculate the fault current in per-unit for a bolted double line-to-ground short circuit to ground at bus 7. Prefault load current and D-Y transformer phase shift are neglected. (d) Calculate the per-unit line-to-ground voltages at faulted bus 7 and bus 6 during the fault in C.arrow_forward
- Figure shows a sample power system network and Zpus Matrix elements. For a solid three phase fault take place at bus 3. Determine a) Fault current (b) V1 , V21 and Var (c) Post fault current in lines 1-2 and 1-3. The line from bus 1-2 impedance =j1.2p.u The line from bus 2-3 impedance =j0.16p.u The line from bus 3-1 impedance =j1.37p.u The Zbus matrix element values are Zbus Matrix Z13 = 0.4; Zbus Matrix Z23 =1.01; Zbus Matrix Z33 =1.55; Fault Post fault voltage at bus 1 (V1) in p.u Post fault voltage at bus 2 (V21 ) in p.u Post fault voltage at bus 3 (V31 ) in p.u Post fault current( I12) in line between 1-2 in p.u Post fault current (I13) in line between 1-3 in p.uarrow_forwardProblem 5 Thevenin equivalent sequence networks looking into the faulted bus of a power system are given with Z1 = j0.15, Z2 = j0.15, ZO = j0.2, and El =1L0 per unit. Compute the fault currents and voltages for the following faults occurring at the faulted bus: (a) Balanced three-phase fault (b) Single line-to-ground fault (c) Line-line fault (d) Double line-to-ground fault Which is the worst fault from the viewpoint of the fault current?arrow_forward3.On a double line-to-ground faultImmersive reader A) The short-circuit currents in the faulted phases are equal. B) The voltages at the fault point on the faulted phases are zero. C) The phase not involved in the fault has a zero voltage at the fault point. D) There are no circulating currents through the neutrals to ground. E) N. A.arrow_forward
- Problem 5: Thevenin equivalent sequence networks looking into the faulted bus of a power system are given with Z1 = j0.15, Z2 = j0.15, Z0 = j0.2, and El = 1L 0° per unit. Compute the fault currents and voltages for the following bolted faults occurring at the faulted bus: (a) Balanced three-phase fault (b) Single line-to-ground fault (c) Line-line fault (d) Double line-to-ground fault Which is the worst fault from the viewpoint of the fault current?arrow_forwardQ2/The positive-sequence reactances for the power system shown in Figure are in per unit on a common MVA base. Resistances are neglected and the negative-sequence impedances are assumed to be the same as the positive-sequence impedances. A bolted line-to-line fault occurs between phases b and c at bus 2. Before the fault occurrence, all bus voltages are 1.0 per unit. Obtain the positive sequence bus impedance matrix. Find the fault current, the three-phase bus voltages during fault, and the line currents in each phase. T₁ 1 0.15 उह 3 X=j0.05 G₁ j0.6 j0.3 2 T2 j0.05 X=j0.05 G₂arrow_forwardQ.3 When a line-to-ground fault occurs, the current in faulted phase 'a' is 100A. The zero-sequence current in phase 'c' isarrow_forward
- A three-phase short circuit occurs at point P for the system shown in the following figure. (a) Assuming the new bases as 30 MVA and 15 kV from the generator side, draw the per unit impedance diagram. (b) Just before the fault, the voltage at point P was 65 kV. Neglecting pre-fault currents, determine the sub-transient fault current. Also determine the contribution to the fault current from the generator and motor side. bus 1 bus 2 P j50 2 G M 25 MVA 13.8 kV 25 MVA 13.5/68 kV 25 MVA 15 MVA 69/13.2 kV 13 kV 10% 15% 12% 14%arrow_forwardThévenin equivalent sequence networks looking into the faulted bus of a power system are given with ?1=?0.15 , ?2=?0.15 , ?0=?0.2and ?1=1∠0°per unit. Compute the fault currents and voltages for the followingfaults occurring at the faulted bus: (a) Balanced three-phase fault (b) Single line-to-ground fault (c) Line-line fault (d) Double line-to-ground fault Which is the worst fault from the viewpoint of the fault current?arrow_forwardQ1. Given Zo = 0.3L60°, Z¡ = 0.17L80° and, Z2 = 0.45L120°. Compute the fault current and voltages for a Double Line-to-Ground Fault. Note that the sequence impedances are in per- unit. This means that the solution for current and voltage will be in per-unit. [1] Note: Formulas for the reference For Double line to ground fault the positive, negative and zero sequence circuits are connected in parallel The sequence networks are interconnected, as shown in Fig. 8.9 Zo To Because the sequence currents sum to one node, it follows that Vo I, =-(I, +1,) The current I, is the voltage drop across Z, in series with the parallel combination of Z, and V, I = Z, + Z, +Z, V2 Fig 8.9arrow_forward
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