Sub set "insted of" multiple fixed variable

Archiver · April 8, 2015, 2:13pm

Hello,

I am writing a transmission system expansion code in GAMS.

I have the following data:

set N ‘NODES’ /1,2,3,4/;
set s(N) ‘GENERATION NODES’ /1,4/;
set r(N) ‘NON-GENERATION NODES’ /2,3/;
set K(N,N) ‘POSSIBLE TRANSSMISION CABLES’ /(1.2),(1.3),(1.4),(4.2),(4.3)/;

I use a binary variable Y(N,N) to choose which lines to be buildt or not.

My problem:
Is there a way i can variables and Equations to only consider the elements in K(N,N) ?

An axample:
In my objective function the binary variable Y(N,N) is multiplied With a cost.
Some times I get a cost for transmission lines that are not beeing buildt.

I have solved it, for now, like this:

Y.fx(‘1’,‘1’)=0;
Y.fx(‘2’,‘2’)=0;
Y.fx(‘3’,‘3’)=0;
Y.fx(‘4’,‘4’)=0;
Y.fx(‘2’,‘1’)=0;
Y.fx(‘2’,‘2’)=0;
Y.fx(‘2’,‘3’)=0;
Y.fx(‘2’,‘4’)=0;
Y.fx(‘3’,‘1’)=0;
Y.fx(‘3’,‘2’)=0;
Y.fx(‘3’,‘4’)=0;
Y.fx(‘4’,‘1’)=0;

Is there a more elegant way to solve this using the GAMS notation??

Thanx for Your help

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Archiver · April 8, 2015, 4:14pm

Hi Ivan,
you could build a multidimensional set for the “transmission lines that are not beeing buildt”
indeed, your set K(N,N) is its negation, so you can use a new element departing from it… I wrote a similar example, see the displays,
note alias are needed to avoid activation of only the same elements in both sets,
CODE
set
a/1*4/
K(a,a)/(1.1),(1.2),(1.3),(1.4),(4.2),(4.3)/
No_K(a,a);
alias(a,aa);
No_K(a,aa)= no;
No_K(a,aa)= yes $(not K(a,aa));
display k, No_K;

*then you can use No_K as a condition or your equation, as in
*your_equation($No_K(a,aa))…

Cheers!
Roger

2015-04-08 14:13 GMT+02:00 Ivan Nordnes Dahlberg :