GATE EE topic:power-systems PYQs & Answers — Page 2

Questions 11–20 of 64. Imported answers require independent review unless marked reviewed.

In the system shown below, the generator was initially supplying power to the grid. A temporary LLLG bolted fault occurs at F very close to circuit breaker 1. The circuit breakers open to isolate the line. The fault self-clears. The circuit breakers reclose and restore the line. Which one of the following diagrams best indicates the rotor accelerating and decelerating areas?

Diagram for Electrical Engineering question 49

Your answerChoose one option.

Fig. (i)

Diagram for Electrical Engineering question 49 (figure 2)

Fig. (ii)

Diagram for Electrical Engineering question 49 (figure 3)

Fig. (iii)

Diagram for Electrical Engineering question 49 (figure 4)

Fig. (iv)

Diagram for Electrical Engineering question 49 (figure 5)

You can attempt this question now. Sign in to view the answer key, explanations and discussion.Log in to check answer

Two units, rated at 100 MW and 150 MW, are enabled for economic load dispatch. When the overall incremental cost is 10,000 Rs./MWh, the units are dispatched to 50 MW and 80 MW respectively. At an overall incremental cost of 10,600 Rs./MWh, the power outputs of the units are 80 MW and 92 MW, respectively. The total plant MW-output (without overloading any unit) at an overall incremental cost of 11,800 Rs./MWh is ____________ (round off to the nearest integer).

You can attempt this question now. Sign in to view the answer key, explanations and discussion.Log in to check answer

The figure shows the single line diagram of a 4-bus power network. Branches

, and

have impedances

, and

per-unit (pu), respectively, where

, with

and

. The current drawn from each load (marked as arrows) is equal to

pu, where

. If the network is to operate with minimum loss, the branch that should be opened is

Diagram for Electrical Engineering question 19

Your answerChoose one option.

You can attempt this question now. Sign in to view the answer key, explanations and discussion.Log in to check answer

The incremental cost curves of two generators (Gen A and Gen B) in a plant supplying a common load are shown in the figure. If the incremental cost of supplying the common load is Rs. 7400 per MWh, then the common load in MW is ______ (rounded off to the nearest integer).

Diagram for Electrical Engineering question 34

You can attempt this question now. Sign in to view the answer key, explanations and discussion.Log in to check answer

For the three-bus lossless power network shown in the figure, the voltage magnitudes at all the buses are equal to 1 per unit (pu), and the differences of the voltage phase angles are very small. The line reactances are marked in the figure, where

, and

are strictly positive. The bus injections

and

are in pu. If

, where

, and the real power flow from bus 1 to bus 2 is 0 pu, then which one of the following options is correct?

Diagram for Electrical Engineering question 41

Your answerChoose one option.

You can attempt this question now. Sign in to view the answer key, explanations and discussion.Log in to check answer

For a two-phase network, the phase voltages

and

are to be expressed in terms of sequence voltages

and

. The possible option(s) for matrix

is/are

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

You can attempt this question now. Sign in to view the answer key, explanations and discussion.Log in to check answer

Which of the following options is/are correct for the Automatic Generation Control (AGC) and Automatic Voltage Regulator (AVR) installed with synchronous generators?

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

AGC response has a local effect on frequency while AVR response has a global effect on voltage.

AGC response has a global effect on frequency while AVR response has a local effect on voltage.

AGC regulates the field current of the synchronous generator while AVR regulates the generator’s mechanical power input.

AGC regulates the generator’s mechanical power input while AVR regulates the field current of the synchronous generator.

You can attempt this question now. Sign in to view the answer key, explanations and discussion.Log in to check answer

The single line diagram of a lossless system is shown in the figure. The system is operating in steady-state at a stable equilibrium point with the power output of the generator being

, where

is the load angle and the mechanical power input is

. A fault occurs on line 2 such that the power output of the generator is less than

during the fault. After the fault is cleared by opening line 2, the power output of the generator is

. If the critical fault clearing angle is

radians, the accelerating area on the power angle curve is _____ times

(rounded off to 2 decimal places).

Diagram for Electrical Engineering question 56

You can attempt this question now. Sign in to view the answer key, explanations and discussion.Log in to check answer

For the three-bus power system shown in the figure, the trip signals to the circuit breakers B₁ to B₉ are provided by overcurrent relays R₁ to R₉, respectively, some of which have directional properties also. The necessary condition for the system to be protected for short circuit fault at any part of the system between bus 1 and the R-L loads with isolation of minimum portion of the network using minimum number of directional relays is

Diagram for Electrical Engineering question 20

Your answerChoose one option.

R₃ and R₄ are directional overcurrent relays blocking faults towards bus 2

R₃ and R₄ are directional overcurrent relays blocking faults towards bus 2 and R₇ is directional overcurrent relay blocking faults towards bus 3

R₃ and R₄ are directional overcurrent relays blocking faults towards Line 1 and Line 2, respectively, R₇ is directional overcurrent relay blocking faults towards Line 3 and R₅ is directional overcurrent relay blocking faults towards bus 2

R₃ and R₄ are directional overcurrent relays blocking faults towards Line 1 and Line 2, respectively.

You can attempt this question now. Sign in to view the answer key, explanations and discussion.Log in to check answer

The expressions of fuel cost of two thermal generation units as a function of the respective power generation

and

are given as

where a is a constant. For a given value of a, optimal dispatch requires the total load of 290 MW to be shared as

and

. With the load remaining unchanged, the value of a is increased by 10% and optimal dispatch is carried out. The changes in

and the total cost of generation, F (= F₁ + F₂) in Rs/hour will be as follows

Your answerChoose one option.

will decrease and F will increase

Both

and F will increase

will increase and F will decrease

Both

and F will decrease

You can attempt this question now. Sign in to view the answer key, explanations and discussion.Log in to check answer

GATE EE topic:power-systems PYQs

Question 49

Question 64

Question 19

Question 34

Question 41

Question 46

Question 47

Question 56

Question 20

Question 21