Page 357 - Decision Making Applications in Modern Power Systems

Heuristic methods for the evaluation of environmental impacts Chapter | 12 319

FIGURE 12.5 Cost of fuel versus output power.
There are various alternatives to consider and minimize the environmen-
tal impact of power plants, which are as follows:
A dispatch alternative strategy that must meet environmental requirement
is to minimize the cost of operation under environmental restrictions.
Control of emissions may be included in conventional ED, adding the
environmental cost to generation costs [2,66]. Emissions are modeled as
a cost to the environment, which are later added to the cost of generation.
The objective function is expressed as follows:

minimize C 5 w 0 F 1 w 1 E S 1 w 2 E N ð12:11Þ
where E S and E N is the emission function of SO 2 and NO x , respectively. w 0 ,
w 1 ; andw 2 are the cost of weight in relation to the fuel (F) and the emissions
of SO 2 and NO x , respectively. F is the function of the cost of fuel, which is
another variation to consider emissions into a single objective function,
where particular weightage is given to NO x and SO 2 emissions.
The functions of the function in emission cost curves of the active power
generated included in function (12.11) can be expressed as follows:
n
X 2
E s 5 ðd i 1 e i P i 1 f i P Þ ð12:12Þ
i
i51
n
X 2
E N 5 ðg i 1 h i P i 1 k i P Þ ð12:13Þ
i
i51
where d i ; e i ; f i ; g i ; h i ; and k i are the estimated parameters based on
the results of the emission tests generating unit, and P i is the power of each
generator.
In this model, when the emission weights are 0, the objective function
becomes a classic problem of ED. In this case the goal is to minimize costs
and total system output. For SO 2 emission, the weights w 0 and w 2 are equal
to 0 and w 1 is equal to 1. For SO 2 , the goal is to minimize the emission. For
NO x emission, the weights w 0 and w 1 are 0 and w 2 is equal to 1, where the
problem lies in the minimization of NO x emissions. On the contrary, when