Parallel Operation of Alternators

Q. Two generating units rated 300 MW and 400 MW have governor speed regulation of 6% and 4% respectively from no load to full load. Both the generating units are operating in parallel to share a load of 600 MW. Assuming free governor action the load shared by the larger unit is

1. 400

Q. Two generators A and B each having 4% speed regulation rated at 200 MW and 400 MW respectively are operating in parallel. When the total load is 300 MW, the loads shared by generators A and B would be respectively___.

1. 125 MW and 175 MW
2. 100 MW and 200 MW
3. 140 MW and 160 MW
4. 150 MW and 150 MW

Q. An alternator operating at 50 Hz is delivering 40 MW power to a system. Due to increase in load, generation was increased by 5 MW using droop control with frequency value dropping by 0.50% of rated value. As load further increases, the frequency of operation becomes 49.20 Hz and hence the power supplied by alternator at this frequency will be

1. 47 MW
2. 56 MW
3. 52 MW
4. 50 MW

Q. If the regulation R = 1% and damping coefficient D = 0.8, the change in generation of the area for a drop in frequency of 0.0015 p.u. in p.u. is

1. 0.0015
2. -0.0015
3. 0.15
4. -0.15

Q. Two 200 MVA alternators operate in parallel. The frequency drops in first machine from 50 Hz at no load to 48 Hz at full load, where as in case of other machine, the frequency drops from 50 Hz to 47 Hz under the same conditions. If the two machines has to share a total load of 300 MW, then the maximum load at unity p.f. which can be delivered by the two machines without overloading any of them is

1. 380 MW
2. 303.33 MW
3. 333.33 MW
4. 200 MW

Q. Two generators $G_1$ and $G_2$ rated as 200 MW and 400 MW respectively, are operating in parallel. The droop characteristics of their governors are 4% and 5% respectively from no load to full load. At no load, the generators are operating at a system frequency of 50 Hz. If total load of 600 MW is being shared by the generators, then generation in $G_1$ and $G_2$ are respectively

1. 266.67 MW, 333.33 MW
2. 300 MW, 300 MW
3. 231 MW, 369 MW
4. 150 MW, 450 MW

Q. A power system consists of two synchronous generators P and Q of rating 300 MVA and 450 MVA with inertia constant 1.8 pu and 1.0 pu respectively. On their own base MVA ratings, the value of equivalent per unit inertia constant for the parallel system on 200 MVA common base will be

1. 4.95 pu
2. 1.50 pu
3. 3.45 pu
4. 2.05 pu

Q. In a turbine generator set R = 0.04 p.u. based on the generator rating of 100 MVA and 60 Hz. the generation frequency decreases by 0.02 Hz and the system adjusts to steady - state operation. The turbine output power increase by

1. 1 MW
2. 1.2 MW
3. 0.83 MW
4. 0.63 MW