An area induces two turbine-generator units rated at 500 and 750 MVA and 50 Hz for which R1 = 0.04 p.u. and Rq = 0.05 p.u. based on their respective ratings. Each unit carries a 300 MVA steady state load. The load on system suddenly increases by 200 MVA. Determine change in frequency on 50 Hz base is _____ (choose base MVA as 100 MVA).
Question 2
Transient stability of a synchronous generator feeding power to an infinity bus through a transmission line can be increased by
(i) Increasing the steam input supply to the turbine driving the generator during the fault clearing.
(ii) Connecting resistors at the generator terminals during fault condition.
(iii) Employing faster excitation system.
(iv) Quickly throwing off the generator load.
Which of these statements are correct?
Question 3
A 100 MVA, 50 Hz alternator is operating at rated speed. The H constant of the machine is 5 MJ/MVA. The load suddenly increases by 50 MW. Due to delay in governor action, there is a delay of 0.5 sec in opening of steam value. The frequency deviation in percentage is
Question 4
A 50 Hz synchronous generator is connected to an infinite bus through a line. The per unit reactance of generator and the line are j0.3 p.u and j0.2 p.u. The generator no load voltage is 1.1 p.u and that of infinite bus is 1 p.u. The inertia constant of the generator is 3 MW-sec/MVA. If the generator is loaded to 60% of its maximum power transfer capacity, then then resulting time of oscillation is ________.
Question 5
A sending end bus transfers power through a transmission line of p.u. impedance of 0.1. If the stability margin is 40%. Find the operating power. Assume constant 1.0 p.u. bus voltage at both the ends.
Question 6
A 20 MVA, 11.2 kV, 4-pole, 50 Hz alternator has an inertia constant of 15 MJ/MVA . If the input and output powers of the alternator are 15 MW and 10 MW, respectively, the angular acceleration in mechanical degree/s2 is __________. (round off to nearest integer)
Question 7
A three-phase, 50 Hz, star-connected, 100 MVA alternator has inertia constant H = 5 MJ/MVA. Initially it delivers 60 MW at equilibrium. If the prime mover input is suddenly increased to 70 MW and initial load angle is 30° then which of the following statement(s) is/are correct.
1). Inertia constant, M =
2). Rotor acceleration is 180 electrical degree/s2
3). Change in load angle is 1.296° after 6 cycles
4). Load angle after 7 cycle is 31.764° electrical
