## Unit commitment - Stntax for min run/down time

Problems with modeling
rpereira57
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Posts: 5
Joined: 4 months ago

### Unit commitment - Stntax for min run/down time

Hello my friends, I have an UC problem to solve using GAMS, however I got stuck on how I can write the equations constraints for the min run/down time, I will post here my code:

Code: Select all

``````sets
time periods of time for generation /1*10/
gen generators /1*5/

table gendata(gen,*) generator parameters
*                           fixed    variable   start up
*                           cost     cost       cost
pmin     pmax      A        B          C           D     E
1        50       110       40       9          220         25    0
2        80       240       55       5          500         20    0
3        70       140       90       8          350         40    0
4        50       130       60       6          290         30    0
5        20       45        30       12         110         80    0

table pdata(time,*) data for each period
*        Demand  Wind
D       R
1        450     80
2        420     105
3        370     120
4        440     90
5        450     50
6        400     75
7        500     35
8        530     75
9        510     20
10       470     80

variables
z overall cost - objective variable
z_1 (time)    ;
Positive Variables
p(gen,time) output power of generators;

binary variables
v(gen,time) is equal to 1 if generator is on for that period
x(gen,time) is equal to 1 if generator started up
y(gen,time) is equal to 1 if generator is started-up for period time
s(gen,time) is equal to 1 if generator is shut down in period time;

Parameter wind(time);

wind(time) = pdata(time,"R")\$(pdata(time,"R") le pdata(time,"D")*0.2) + pdata(time,"D")*0.2\$(pdata(time,"R") gt pdata(time,"D")*0.2) ;

equations
cost objective function
cost_1 (time)
Start_up(gen,time)
pmax(gen,time) maximum output power
pmin(gen,time) minimum output power

cost .. z =e= sum((gen,time), gendata(gen,"A")*v(gen,time)+gendata(gen,"B")*p(gen,time)+gendata(gen,"C")*x(gen,time));
cost_1 (time)..  z_1 (time) =e=  sum(gen, gendata(gen,"A")*v(gen,time)+gendata(gen,"B")*p(gen,time)+gendata(gen,"C")*x(gen,time));
Start_up(gen,time).. x(gen,time)=e=v(gen,time)-v(gen,time-1);
pmax(gen,time).. p(gen,time)=l=gendata(gen,"pmax")*v(gen,time);
pmin(gen,time).. p(gen,time)=g=gendata(gen,"pmin")*v(gen,time);

model uc /all/;
uc.optcr=0.001;

solve uc using mip minimizing z;

display z.l, p.l,x.l,z_1.l;
``````
===============================================================================
it is working fine, however this new questions is add:

Units 1, 4 and 5 have been online for 5, 3 and 4 hours, respectively, at the start of the 10 hour period, while units 2 and 3 have been offline for 3 and 2 hours, respectively. If all unit constraints and costs are applied, i.e. including minimum run times and down times, determine the optimal unit commitment and economic dispatch, and the associated cost, for the 10 hour period.

Hint: Conditional constraints and the alias command may be helpful in formulating constraints relating to the minimum run and down times.

Hint: The GAMS program formulation can be simplified if the predicted demand and wind generation profiles for hours 11 - 15 are also known. Assume the following predicted demand and wind profiles:

11 12 13 14 15
Demand (MW) 480 450 410 390 440
Wind (MW) 70 30 85 40 25

please can anyone help, I tried everything.

thanks

flynn_dawg
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Posts: 2
Joined: 3 months ago

### Re: Unit commitment - Stntax for min run/down time

Why did you change some of the values given?

flynn_dawg
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Posts: 2
Joined: 3 months ago

### Re: Unit commitment - Stntax for min run/down time

Why did you change some of the values given?

Taka
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Posts: 2
Joined: 1 month ago

### Re: Unit commitment - Stntax for min run/down time

hi did you get the solution to your question? if yes may you please help me on how i can include those conditional contraints.

Hefeng Zhai
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Posts: 3
Joined: 2 months ago

### Re: Unit commitment - Stntax for min run/down time

There may be the program code you want. Please see attached file.

Best Regards!
Attachments
Power System Optimization Modeling in GAMS-6.pdf