Handbook of Electrical Engineering

GAS TURBINE DRIVEN GENERATORS 49

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

P 1 +P 1

G 1

=K 1

Similarly for generators Nos. 2 and 3,

P 2 +P 2

G 2

=K 2 and

P 3 +P 3

G 3

=K 3

For the generators to be equally loadedK 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,

K=

P 1 +P 1 +P 2 +P 2 +P 3 +P 3

G 1 +G 2 +G 3

K=

40. 5

20 + 15 + 10

= 0. 9

Therefore since

P 1 +P 1

G 1

= 0. 9

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,

fz 1 = 59. 25101 +

0. 03 × 18. 00 × 60. 0

20. 0

=60.871 Hz