[Help-glpk] binary decision variables, --nomip

[Linder Wolfgang]

Hello,

 

I have defined binary decision variables in order to allow production only at certain levels:

 

s.t. Limit_power_levels1{t in TIME}: P[t] - (sum{lev in PLEVELS} exactprod[t,lev]*plev[lev]) = 0;

s.t. Limit_power_levels2{t in TIME}: sum{lev in PLEVELS} exactprod[t,lev] = 1;

 

…

set PLEVELS:=  1 2 3 4;

param plev:=

1 0

2 10

3 25

4 40

 

plev are the allowed production levels, exactprod are the binary decision variables, P is the production

 

This works very well.

However, I would like to run the program with the –nomip option because of increased speed. Obviously, in this case the binary decision variables are not necessarily binary any more.

At most timesteps they still take the values of 0 or 1, but for example in timestep 4 they don’t (see below).

Are there any additional conditions I could use in order to force the variables exactprod to be quasi-binary while still using the –nomip option?

 

Thank you very much for your help

 

Wolfgang

 

 

 

Time Price P exactprod(t,1) exactprod(t,2) exactprod(t,3) exactprod(t,4)

1 10    0        1.0  0.0  0.0  0.0

2  20    0        1.0  0.0  0.0  0.0

3  30    0        1.0  0.0  0.0  0.0

4  40   10        0.8  0.0  0.0  0.2

5  45   40        0.0  0.0  0.0  1.0

6  65   40        0.0  0.0  0.0  1.0

7  60   40        0.0  0.0  0.0  1.0

8  55   40        0.0  0.0  0.0  1.0

9  50   40        0.0  0.0  0.0  1.0

10  45   40        0.0  0.0  0.0  1.0

11  25    0        1.0  0.0  0.0  0.0

12  10    0        1.0  0.0  0.0  0.0