Page 70 - Handbook of Electrical Engineering

GAS TURBINE DRIVEN GENERATORS 49

For generator No. 1, the ratio K 1 of its new load to its rating is,

P 1 + P 1
= K 1
G 1
Similarly for generators Nos. 2 and 3,

P 2 + P 2 P 3 + P 3
= K 2 and = K 3
G 2 G 3
For the generators to be equally loaded K 1 = K 2 = K 3 =K.

In addition the ratio of the total load to the total of the generator ratings must be the same as
for each generator,
Hence,

P 1 + P 1 + P 2 + P 2 + P 3 + P 3
K =
G 1 + G 2 + G 3
40.5
K = = 0.9
20 + 15 + 10

Therefore since
P 1 + P 1
= 0.9
G 1
P 1 = (0.9 × 20) − 10.0 = 8.00 MW
so that
P 1 + P 1 = 18.00 MW (90%)

and
P 2 = (0.9 × 15) − 10.0 = 3.5 MW

so that
P 2 + P 2 = 10.0 + 3.5 = 13.5 MW (90%)

and
P 3 = (0.9 × 10) − 5.0 = 4.0 MW

so that
P 3 + P 3 = 5.0 + 4.0 = 9.0 MW (90%)
Step 6. Find the new set points.

From (2.62), for generator No. 1, using the original frequency of 59.25101 Hz, found in Step 2,
0.03 × 18.00 × 60.0
f z1 = 59.25101 +
20.0
= 60.871 Hz