Electrical Power Systems

Optimal System Operation 419
Equation (16.34) indicates that for optimal scheduling, operate all the generators such that
the product Li × dCi
dP
gi
= l for every generator.
rom eqn.(16.34), it is seen that the ICs must be weighted by the penalty factors Li. A large
penalty factor makes the plant less attractive, and a smaller IC from the plant is required.
If we now consider the generator limit, same procedure as mentioned in section–16.5 must
be adopted.
Example 16.4: A two bus power system is shown in ig.16.8. Incremental fuel costs of the two
generators are given as:
IC1 = (0.35 Pg1 + 41) Rs/MWhr
IC2 = (0.35 Pg2 + 41) Rs/MWhr
loss expression is
PL = 0.001(Pg2 – 70) 2 MW.
Determine the optimal scheduling and power loss of the transmission link.
Solution:
and
ig. 16.8: Sample power system of Ex–16.4.
P
P
P L = 0.001(P g2 – 70) 2
L
g2
Now L1 dC1
dPg1
L 2
dC
dP
= 0.002 (P g2 – 70) = 0.002 P g2 – 0.14
L 1 = 1.0, L 2 =
2
g2
1
1 - P
P
L
g2
=
1
d114 . - 0. 002Pg2i
= 0.35 P g1 + 41 = l ...(i)
=
035 . Pg2
+ 41
114 . - 0. 002P
d g2i
= l ...(ii)