Hi people,

I am doing economic dispatch of sources. Program was compilated

without errors. But offered results seem

strange! As you can see (below) for contracted amount of power at

time

window 3, the program computed the negative value of power for

source

1 (what is physical nonsense). In spite of bounds (power limits) are

treated as variables P.up(n,t) = Par(n,“up_bound”); P.lo(n,t) =

Par(n,“lo_bound”); with specified lower and upper bounds according

to

table Par(n, head). Whats more the status of model is “infeasible”.

That means that program did not respect the bounds

(feasible region). Why it happened? How to treat this problem? Thank

you in advance for your warm help.

Kindly, Jan

Here is source code:

Sets

n “number of generators” /1*4/
t “number of time windows” /1*3/

head “head of table” /up_bound, lo_bound, prize, fix_cost, dep_cost/;

Parameters P_doh(t) contracted amount of power

/1 3510, 2 2720, 3 510/

Table Par(n,head) “generators parameters”

up_bound lo_bound prize fix_cost

dep_cost

1 1200 0 97.98e-3

10 14.4625e-3

2 1800 900 129.44e-3 30

50.575e-3

3 200 0 58.6e-3

0 0

4 5000 0 0

0 1500e-3;

Variables

P(n,t) power of n-th generator in time t

Z profit from selling energy;

P.up(n,t) = Par(n,“up_bound”);

P.lo(n,t) = Par(n,“lo_bound”);

Equations

Obj objective function

GenLow(n,t) lower bound

GenUp(n,t) upper bound

SysBal(t) power balance equation;

Obj…0=e=sum((n,t),Par(n,“prize”)*P(n,t)-

Par(n,“dep_cost”)*P(n,t)-Par(n,“fix_cost”))-Z;

GenLow(n,t) … P(n,t) =g= Par(n,“lo_bound”);

GenUp(n,t) … P(n,t) =l= Par(n,“up_bound”);

SysBal(t)… sum((n),P(n,t))-P_doh(t)=e=0;

Model VPP “controling OZE” /all/;

solve VPP using mip maximizing Z;

Here are results:

VAR P power of n-th generator in time t

LOWER LEVEL UPPER MARGINAL

1.1 . 1200.000 1200.000 EPS

1.2 . 1200.000 1200.000 EPS

1.3 . -390.000 1200.000 1.000 INFES

2.1 900.000 1800.000 1800.000 EPS

2.2 900.000 1520.000 1800.000 .

2.3 900.000 900.000 1800.000 2.000 INFES

3.1 . 200.000 200.000 EPS

3.2 . . 200.000 EPS

3.3 . . 200.000 2.000 INFES

4.1 . 310.000 5000.000 .

4.2 . . 5000.000 EPS

4.3 . . 5000.000 2.000 INFES

LOWER LEVEL UPPER MARGINAL

---- VAR Z -INF 780.000 +INF .

Z profit from selling energy

**** REPORT SUMMARY : 0 NONOPT

5 INFEASIBLE (INFES)

SUM 780.000

MAX 390.000

MEAN 156.000

0 UNBOUNDED

**** SOLVER STATUS 1 Normal Completion

**** MODEL STATUS 4 Infeasible

**** OBJECTIVE VALUE 780.0000

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