Help! Dynamic constraint definition for power system MIP optimization in Gurobi
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To whom it may concern at Gurobi Support,
I hope you are doing well.
I have below some Python code that I would like to convert to a Gurobi constraint, however, I am running into issues. I am trying to solve an MIP Unit Commitment problem .
The code that I'd like to convert to a Gurobi constraint is:
for t in time_periods:
UT = min(gen['time_up_minimum'],data['time_periods'])
if t >= UT:
m.uptime[g,t] = sum(m.vg[g,t] for t in range(t-UT+1, t+1)) <= m.ug[g,t]
UT is a list that contains data of the uptime of each generator each hour.
My attempt at making this Python loop a Gurobi constraint is below. Note that I use the variable 'p' as the equivalent iterator 't'
min_uptime = model.addConstrs(gp.quicksum(nstart[g, p] for p in range(p-UT+1,p+1)) <= ngen[g, periods]
for g in range(ngens) for periods in range(nperiods))
The error that results when I run my code is
File C:/Users/... test.py:60 in <genexpr>
min_uptime = model.addConstrs(gp.quicksum(nstart[g, p] for p in range(p-UT+1,p+1)) <= ngen[g, periods]
NameError: name 'p' is not defined
I know that the issue stems from the part:
... for p in range(p-UT+1,p+1)) ...
I believe the issue is that this is a dynamic constraint, meaning the constraint is not constant; it changes every time period, 'p'. I cannot think of a way to include a way to iterate through p inside the range like the Python code iterates with 't'.
What do you think?
Thanks in advance!!!
Elliott Fix
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Gurobi Staff
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Hi Elliott,
In your code that you would like to convert, it would be best to not misuse \(\texttt{t}\) as iterator and fixed value. I think that the following should also work for you
for T in time_periods:
UT = min(gen['time_up_minimum'],data['time_periods'])
if T >= UT:
m.uptime[g,t] = sum(m.vg[g,t] for t in range(T-UT+1, T+1)) <= m.ug[g,T]You can then convert the above to Gurobi code by looping over time_periods and adjusting \(\texttt{p}\) to \(\texttt{T}\) in the \(\texttt{range}\) function.
Best regards,
Jaromił0 -
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