GATE EE Power Systems PYQs & Answers — Page 3

Questions 21–30 of 64. Imported answers require independent review unless marked reviewed.

The bus admittance (

) matrix of a 3-bus power system is given below.

Considering that there is no shunt inductor connected to any of the buses, which of the following can NOT be true?

Your answerSelect all correct options. You can choose more than one.

Line charging capacitor of finite value is present in all three lines

Line charging capacitor of finite value is present in line 2-3 only

Line charging capacitor of finite value is present in line 2-3 only and shunt capacitor of finite value is present in bus 1 only

Line charging capacitor of finite value is present in line 2-3 only and shunt capacitor of finite value is present in bus 3 only

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A 50 Hz, 275 kV line of length 400 km has the following parameters:

Resistance, R = 0.035 Ω/km; Inductance, L = 1 mH/km; Capacitance, C = 0.01 μF/km;

The line is represented by the nominal-π model. With the magnitudes of the sending end and the receiving end voltages of the line (denoted by

and

, respectively) maintained at 275 kV, the phase angle difference (

) between

and

required for maximum possible active power to be delivered to the receiving end, in degree is __________ (Round off to 2 decimal places).

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The three-bus power system shown in the figure has one alternator connected to bus 2 which supplies 200 MW and 40 MVAr power. Bus 3 is infinite bus having a voltage of magnitude

p.u. and angle of

. A variable current source,

is connected at bus 1 and controlled such that the magnitude of the bus 1 voltage is maintained at 1.05 p.u. and the phase angle of the source current,

, where

is the phase angle of the bus 1 voltage. The three buses can be categorized for load flow analysis as

Diagram for Electrical Engineering question 41

Your answerChoose one option.

Bus 1 Slack bus Bus 2 P − |V| bus Bus 3 P − Q bus

Bus 1 P − |V| bus Bus 2 P − |V| bus Bus 3 Slack bus

Bus 1 P − Q bus Bus 2 P − Q bus Bus 3 Slack bus

Bus 1 P − |V| bus Bus 2 P − Q bus Bus 3 Slack bus

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The two-bus power system shown in figure (i) has one alternator supplying a synchronous motor load through a Y-Δ transformer. The positive, negative and zero-sequence diagrams of the system are shown in figures (ii), (iii) and (iv), respectively. All reactances in the sequence diagrams are in p.u. For a bolted line-to-line fault (fault impedance = zero) between phases ‘b’ and ‘c’ at bus 1, neglecting all pre-fault currents, the magnitude of the fault current (from phase ‘b’ to ‘c’) in p.u. is __________ (Round off to 2 decimal places).

Diagram for Electrical Engineering question 60

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The geometric mean radius of a conductor, having four equal strands with each strand of radius

, as shown in the figure below,

Diagram for Electrical Engineering question 14

Your answerChoose one option.

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The valid positive, negative and zero sequence impedances (in p.u.), respectively, for a 220 kV, fully transposed three-phase transmission line, from the given choices are

Your answerChoose one option.

1.1, 0.15 and 0.08

0.15, 0.15 and 0.35

0.2, 0.2 and 0.2

0.1, 0.3 and 0.1

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The fuel cost functions in rupees/hour for two 600 MW thermal power plants are given by

Plant 1:

Plant 2:

where

and

are power generated by plant 1 and plant 2, respectively, in MW and

is constant. The incremental cost of power (

) is 8 rupees per MWh. The two thermal power plants together meet a total power demand of 550 MW. The optimal generation of plant 1 and plant 2 in MW, respectively, are

Your answerChoose one option.

200, 350

250, 300

325, 225

350, 200

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Two generating units rated for 250 MW and 400 MW have governor speed regulations of 6% and 6.4%, respectively, from no load to full load. Both the generating units are operating in parallel to share a load of 500 MW. Assuming free governor action, the load shared in MW, by the 250 MW generating unit is ________. (round off to nearest integer)

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Consider a power system consisting of

number of buses. Buses in this power system are categorized into slack bus, PV buses and PQ buses for load flow study. The number of PQ buses is

. The balanced Newton-Raphson method is used to carry out load flow study in polar form,

and

are sub-matrices of the Jacobian matrix

as shown below:

The dimension of the sub-matrix

Your answerChoose one option.

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Two generators have cost functions

and

. Their incremental-cost characteristics are

They need to deliver a combined load of 260 MW. Ignoring the network losses, for economic operation, the generations

and

(in MW) are

Your answerChoose one option.

P₁ = P₂ = 130

P₁ = 160, P₂ = 100

P₁ = 140, P₂ = 120

P₁ = 120, P₂ = 140

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GATE EE Power Systems PYQs

Question 28

Question 33

Question 41

Question 60

Question 14

Question 15

Question 43

Question 56

Question 9

Question 10