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GATE 2020 || Power Systems || Quiz 8
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Question 1
A 50 Hz generating unit has H-constant of 2 MJ/MVA. The machine is initially operating in steady state at synchronous speed, and producing 1 pu of real power. The initial value of the rotor angle δ is 5 °, when a bolted three phase to ground short circuit fault occurs at the terminal of the generator. Assuming the input mechanical power to remain at 1 pu, the value of δ in degrees, 0.02 second after the fault is _________.
Question 2
The figure shows the single line diagram of a power system with a double circuit transmission line.
The expression for electrical power is 1.5 sinδ, where δ is the rotor angle. The system is operating at
the stable equilibrium point with mechanical power equal to 1 pu. If one of the transmission line
circuits is removed, the maximum value of δ, as the rotor swings is 1.221 radian. If the expression for electrical power with one transmission line circuit removed is Pmax sinδ, the value of Pmax, in pu
is ________.
The expression for electrical power is 1.5 sinδ, where δ is the rotor angle. The system is operating at
the stable equilibrium point with mechanical power equal to 1 pu. If one of the transmission line
circuits is removed, the maximum value of δ, as the rotor swings is 1.221 radian. If the expression for electrical power with one transmission line circuit removed is Pmax sinδ, the value of Pmax, in pu
is ________.
Question 3
A generator delivers power of 1.0 p.u. to an infinite bus through a purely reactive network. The maximum power that could be delivered by the generator is 2.0 p.u. A three phase fault occurs at the terminals of the generator which reduces the generator output to zero. The fault is cleared after tc second. The original network is then restored. The maximum swing of the rotor angle is found to be δmax = 110 electrical degree. Then the rotor angle in electrical degrees at t = tc is
Question 4
Consider a synchronous generator connected to an infinite bus by two identical parallel transmission lines. The transient reactance x of the generator is 0.1 pu and the mechanical power input to it is constant at 1.0 pu. Due to some previous disturbance, the rotor angel (δ) is undergoing an undammed oscillation, with the maximum value of δ(t) equal to 130o. One of the parallel lines trips due to relay maloperation at an instant when δ(t) = 130O as shown in the figure. The maximum value of the per unit line reactance, x, such that the system does not lose synchronism subsequent to this tripping is
Question 5
A synchronous generator is connected to an infinite bus through a lossless double circuit transmission line. The generator is delivering 1.0 per unit power at a load angle of 30 ° when a sudden fault reduces the peak power that can be transmitted to 0.5 per unit. After clearance of fault, the peak power that can be transmitted becomes 1.5 per unit. Find the critical clearing angle.
Question 6
For the system shown below. SD1 and SD2 are complex power demands at bus 1 and bus 2 respectively. If |V2| = 1 pu, the VAR rating of the capacitor (QG2) connected at bus 2 is
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Nov 19ESE & GATE EE
