[Couenne] Error in _cmdno 308 / can't open C:\Users\...\Temp\at1988.sol

[Tom Van Acker]

Dear reader,

I am programming a topology optimization for a meshed power system. The problem is a Mixed Integer Non Convex Quadratic Constraint Problem and to solve this I am using Couenne as a solver in AMPL. The solution to the problem allows several options of adjusting the topology. Certain topology adjustments could lead to an infeasible solution, in that case another topology adjustment should be tried. If I try to solve the problem using a topology adjustment that leads to an infeasible solution I get the following output in AMPL:

Couenne 0.4.7 --  an Open-Source solver for Mixed Integer Nonlinear Optimization
Mailing list: couenne at list.coin-or.org
Instructions: http://www.coin-or.org/Couenne
couenne:
ANALYSIS TEST:  Couenne: Warning, tightened NLP is infeasible
problem infeasible
Error at _cmdno 308 executing "solve" command
(file TOPOP.run, line 96, offset 3162):
can't open C:\Users\tvanacke\AppData\Local\Temp\at1988.sol

And after this error, the program is interrupted (after the solve; line), which it should not do. In a correct situation it should move on to another topology switching possibility (mode), as can be seen in the code. Is there any way to address this problem so the optimization can be continued?

repeat                                                                    {
if (mode == 3 and submode > 2)                        then {

       drop {g in G}                                  GBC[g];
       restore {g in G}                               GBO[g];

       option                                         solver couenne;
       option                                         lp_solver cplex;
       solve;

       let                                            mode := 4;
       if solve_result_num < 100                      then {
             let                                     submode := 999;
             print                                   '------------------------------------SUBOPTIMAL SOLUTION FOUND-------------------------------------';
             display                                  Isc;
             display                                 D;
             display                                 OBJ2;
             print                                   '--------------------------------------------------------------------------------------------------';
       }
}
if (mode == 2 and submode > 1)                        then {

       drop {bi in BI}                                       BIBC[bi];
       drop {bo in BO}                                       BOBC[bo];
       restore {bi in BI}                                    BIBO[bi];
       restore {bo in BO}                                    BOBO[bo];

       option                                                solver couenne;
       option                                                lp_solver cplex;
       solve;

       let                                                   mode := 3;
       if solve_result_num < 100                      then {
             let                                            mode := 4;
             let                                            submode := 999;
             print                                          '------------------------------------SUBOPTIMAL SOLUTION FOUND-------------------------------------';
             display                                        Isc;
             display                                        D;
             display                                        OBJ2;
             print                                          '--------------------------------------------------------------------------------------------------';
       }
}

if mode == 1                                                then {

       restore {g in G}                                      GBC[g];
       restore {bi in BI}                                    BIBC[bi];
       restore {bo in BO}                                    BOBC[bo];

       option                                                solver couenne;
       option                                                lp_solver cplex;
       solve;

       let                                                   mode := 2;
       if solve_result_num < 100                             then {
             let                                            submode := 999;
             print                                          '--------------------------------------OPTIMAL SOLUTION FOUND--------------------------------------';
             display                                        Isc;
             display                                        D;
             display                                        OBJ2;
             print                                          '--------------------------------------------------------------------------------------------------';
       }
}

}
while                                                       mode < 4;

With kind regards,

Tom Van Acker
--
Tom Van Acker
Researcher - University of Leuven (KU Leuven)
Department Electrical Engineering (ESAT) - Research group Electrical Energy (ELECTA)
Kasteelpark Arenberg 10 - 3001 Heverlee - Belgium
WORK: +32 16 37 93 06
GSM: +32 (0)478 771 361 (mobile)
Email: Tom.VanAcker at esat.kuleuven.be<mailto:Tom.VanAcker at esat.kuleuven.be>

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