Composite Generating Cost Function Refer to Example 1 given, where three generating units are combined into a single composite generating unit. Repeat the example, except develop an equivalent incremental cost characteristic using only the incremental characteristics of the three units. Using this composite incremental characteristic plus the zeroload intercept costs of the three units, develop the total cost characteristic of the composite. (Suggestion: Fit the composite incremental cost data points using a linear approximation and a least-squares fitting algorithm.)

Example 1:-
The three generating units from Example 3A are to be combined into a composite generating unit. The fuel costs assigned to these units will be

Fuel cost for unit1 = 1.1 $/MBtu
Fuel cost for unit2 = 1.4 $/MBtu
Fuel cost for unit3 = 1.5 $/MBtu

Example 3A
Suppose that we wish to determine the economic operating point for these three units when delivering a total of 850 MW. Before this problem can be solved, the fuel cost of each unit must be specified. Let the following fuel costs be in effect.