/* Power plant LP scheduler */
/* Implemented, inspected, written and converted to GNU MathProg
by NASZVADI, Peter, 199x-2017 <vuk@cs.elte.hu> */
/*
Fast electric power plant scheduler implementation based on new
results in author's Thesis.
The base problem is:
* given some power plants
* a short time scale partitioned to equidistant intervals
* the task is to yielding the cheapest schedule for the plants
* the daily demand forecast is usually accurate and part of the input
The power plants has technical limitations:
* upper and lower bounds of produced energy
* and also a gradient barrier in both directions
(can depend on time, but this GMPL implementation is simplified)
* Also units with same properties (technical and price) should be
scheduled together usually with near same performance values
* Assumed a simplified network topology, which is contractive, so
keeping Kirchhoff's laws is a necessary constraint too
* All solutions must be integer
The LP relaxation is equivalent with the MIP problem due to the
model's matrix interesting property: it is Totally Unimodular
(proven in 2004 by author) and also a Network Matrix (2006,
presented at OTDK 2016, Szeged, Hungary) so:
* it is strictly polynomial if it is solved by most simplex algs
* all base solutions become integer if the RHS vector is integer
(it is in real life, so this is an acceptable assumption)
* The transposed matrix is NOT a Network Matrix in most cases!
However, adding several other constraints easily turns the problem
to be NP-hard, which is also pinpointed and discussed in the Thesis.
See more about electric power plants' scheduling in the
author's Thesis (in Hungarian):
http://www.cs.elte.hu/matdiploma/vuk.pdf
It is possible to run with custom parameters, what is needed
to define is:
* TIME set (daylightsaving cases or other than hour intervals)
* PLANTS set (the 'Demand' is mandatory and usually negative)
* PRICE parameter (can be negative if energy is sold to a consumer)
* BOUND parameter (technical bounds)
* MAXGRAD parameter (technical bounds)
Then generate a pretty-printed solution by typing:
glpsol --math powplant.mod [--data NEW_DATA.dat]
where "NEW_DATA.dat" should contain the above 5 structures filled
with custom data. Square brackets shoudn't be entered, and specifying
custom data file is optional.
*/
set TIME, default {
'00:00', '01:00', '02:00', '03:00', '04:00',
'05:00', '06:00', '07:00', '08:00', '09:00',
'10:00', '11:00', '12:00', '13:00', '14:00',
'15:00', '16:00', '17:00', '18:00', '19:00',
'20:00', '21:00', '22:00', '23:00', '24:00'
};
/* Time labels, assumed natural ordering. daylightsaving's bias
can be inserted p.ex. in Central Europe like:
... '01:00', '02:00', '02:00b', '03:00', ... */
set TADJ := setof{(r, s) in TIME cross TIME: r < s}(r, s) diff
setof{(t, u, v) in TIME cross TIME cross TIME: t < u and u < v}(t, v);
/* Tricky adjacent time label generator because GMPL lacks order determination
of set elements (except intervals composed of equidistant numbers) */
set PLANTS, default {'Demand'};
/* Demand is a promoted, mandatory one, usually filled
with negative MW values in data section */
set DIRECTION, default {'Up', 'Down'};
/* All possible directions of gradients, do not touch */
param MAXINT, default 10000;
/* A "macro" for bounding absolute value of all used numbers
and used as default value */
param PRICE{PLANTS}, default MAXINT;
/* Should be specified in data section, self-explanatory.
can be negative if there are energy buyers */
param BOUND{(p, t, d) in PLANTS cross TIME cross DIRECTION},
default if t = '00:00' then if d = 'Down' then BOUND[p, t, 'Up'] else 0 else
if p <> 'Demand' or d = 'Up' then sum{(u, v) in TADJ: v = t} BOUND[p, u, d]
else BOUND[p, t, 'Up'];
/* Obvious, technical bounds of each power plant unit (real or virtual like
'Demand'). If some parts are not given in data section, calculated
from preceeding values. Also for time '00:00', its 'Down' values by
default are the same as denoted with 'Up' */
param MAXGRAD{(p, d) in PLANTS cross DIRECTION}, default MAXINT;
/* Usually nonnegative integer, might differ in distinct directions per unit
in the cited thesis, it is allowed to gradient bounds to depend on time,
but this is a simplified model */
var x{(t, p) in TIME cross PLANTS}, <= BOUND[p, t, 'Up'], >= BOUND[p, t, 'Down'];
/* The schedule, dimension is MW */
s.t. kirchhoff{t in TIME: t <> '00:00'}: sum{p in PLANTS} x[t, p] = 0;
/* Conservative property */
s.t. gradient{(p, t, u) in PLANTS cross TADJ}:
-MAXGRAD[p, 'Down'] <= x[t, p] - x[u, p] <= MAXGRAD[p, 'Up'];
/* Technical limitations, each unit usually cannot change performance
arbitrarily in a short time, so limited in both directions per time unit*/
minimize obj: sum{(t, p) in TIME cross PLANTS}(x[t, p] * PRICE[p]);
/* The objective is the cost of the schedule */
solve;
/* Pretty print solution in table */
printf '+--------+';
for{p in PLANTS}{
printf '-% 6s-+', '------';
}
printf '\n';
printf '|%7s |', ' ';
for{p in PLANTS}{
printf ' % 6s |', p;
}
printf '\n';
printf '+--------+';
for{p in PLANTS}{
printf '-% 6s-+', '------';
}
printf '\n';
for{t in TIME}{
printf '|%7s |', t;
for{p in PLANTS}{
printf ' % 6s |', x[t, p].val;
}
printf '\n';
}
printf '+--------+';
for{p in PLANTS}{
printf '-% 6s-+', '------';
}
printf '\n';
data;
/*
Generated random default values and names, the demand is the sum of
2 sinewaves.
Also specified a treshold for nuclear plants from 15:00 till 19:00
The sun is shining only morning and in the afternoon: 07:00-18:00, so
solar plant cannot produce electric energy after sunset.
Only touch this section, or export it to a data file!
*/
set PLANTS 'Demand', 'Atom1', 'Atom2', 'Coal', 'Gas1', 'Gas2', 'Green', 'Oil', 'Solar', 'Dam';
param PRICE :=
'Demand' 0
'Atom1' 2
'Atom2' 2
'Coal' 15.6
'Gas1' 12
'Gas2' 11.5
'Green' 8.8
'Oil' 23.3
'Solar' 7.6
'Dam' 3;
/* price per MW */
param BOUND :=
[*, *, 'Up'] (tr): 'Atom1' 'Atom2' 'Coal' 'Gas1' 'Gas2' 'Green' 'Oil' 'Solar' 'Dam' :=
'00:00' 240 240 100 150 150 20 90 0 20
'01:00' 240 240 155 192 208 35 230 0 20
[*, *, 'Up'] (tr): 'Atom1' 'Atom2' :=
'15:00' 200 200
'19:00' 235 235
[*, *, 'Up'] (tr): 'Solar' :=
'07:00' 20
'18:00' 0
[*, *, 'Down'] (tr): 'Atom1' 'Atom2' 'Coal' 'Gas1' 'Gas2' 'Green' 'Oil' 'Solar' 'Dam' :=
'01:00' 100 100 50 62 68 0 75 0 20
[*, *, 'Up'] : '01:00' '02:00' '03:00' '04:00' '05:00' '06:00' '07:00' '08:00' :=
'Demand' -868 -851 -837 -791 -887 -912 -1046 -1155
[*, *, 'Up'] : '09:00' '10:00' '11:00' '12:00' '13:00' '14:00' '15:00' '16:00' :=
'Demand' -945 -873 -797 -990 -1241 -1134 -815 -782
[*, *, 'Up'] : '17:00' '18:00' '19:00' '20:00' '21:00' '22:00' '23:00' '24:00' :=
'Demand' -772 -827 -931 -1105 -1215 -1249 -1183 -952;
param MAXGRAD (tr)
: 'Atom1' 'Atom2' 'Coal' 'Gas1' 'Gas2' 'Green' 'Oil' 'Solar' 'Dam' :=
'Up' 30 30 35 89 95 5 56 2 4
'Down' 30 30 45 96 102 5 56 2 4;
end;