Features/schedule for flow

[c-koehl]

Added a schedule for Flow

• Functionality Sometimes it´s important to set a schedule for a flow (e.g. CHP electrical output), e.g. for fulfilling contracts. During optimization flow will be pushed to fulfill the schedule, if possible. If it´s not possible a penalty term will be activated and added to the objective expression for each unit of the difference flow-schedule.

• Changes made in oemof.solph.network

  Parameter added to class Flow:

  • schedule Flow has to follow the schedule, but LP won´t be infeasible, if flow can´t fulfill schedule: slack variables will be added (see Changes made in solph.blocks)
  • penalty_pos Describes the costs associated with one unit of the deficit of the flow (:= slack_pos) compared to the schedule. Costs will be added to the objective expression.
  • penalty_neg Describes the costs associated with one unit of the excessed flow (:= slack_neg). Will be added to the objective expression.

• Changes made in oemof.solph.blocks

  Added Set and Variables to class Flow:

  • SCHEDULE_FLOWS (pyomo.Set) contains all flows with schedules

  • slack_neg (pyomo.Var, within=NonNegativeReals) slack variable for representing excess of flow compared to schedule (see Added constraint to class Flow)

  • slack_pos (pyomo.Var, within=NonNegativeReals) slack variable for representing deficit of flow compared to schedule

  Added constraint to class Flow

  • flow(i, o, t) - slack_neg(i, o, t) + slack_pos(i, o, t) = schedule(i, o, t)

  Term added to objective expression:

  • penalty_pos(i, o, t) * slack_pos(i, o, t) + penalty_neg(i, o, t) * slack_neg(i, o, t)

• Changes made in oemof.tests.test_processing New Parameters of class Flow had to be added to the test file as well.

• Changes made in oemof.tests.constraint_tests Test for scheduled flow was added.

• Changes made in oemof.tests.lp_files.flow_schedule.lp Created file.

• Changes made in doc.whatsnew.v0-3-3.rst Created file.

• Possible Improvements

  • Default value for penalty_pos and penalty_neg is 0. This could be improved by setting a reasonable default value, but this acquires mathematical research on how to choose appropriate penalties.
  • If it's not possible for the flow to follow the schedule, "non-real" costs will be added to the objective expression. You might not want to interfere the artificial costs (added by the slack variables) with the real costs of the solved LP.

[pep8speaks]

Hello @c-koehl! Thanks for updating this PR. We checked the lines you've touched for PEP 8 issues, and found:

• In the file src/oemof/solph/blocks.py:

Line 163:46: W504 line break after binary operator Line 267:53: W504 line break after binary operator Line 268:70: W504 line break after binary operator Line 308:35: W504 line break after binary operator Line 309:37: W504 line break after binary operator Line 312:73: W504 line break after binary operator Line 314:73: W504 line break after binary operator

• In the file src/oemof/solph/network.py:

Line 241:37: W504 line break after binary operator Line 242:48: W504 line break after binary operator

Comment last updated at 2022-06-24 14:12:31 UTC

[coveralls]

Coverage increased (+0.06%) to 94.894% when pulling 4a7106f1e9aa3749bb21add685fdee8dd297cdb1 on c-koehl:features/schedule_for_flow into 83cfc0b6187906d85ebd0c4ea2788e0091dc82f7 on oemof:dev.

[c-koehl]

If you're interested, I could also add an example to oemof-examples.

[gplssm]

Once you're done with the implementation, select a reviewer who cross-checks the newly added code. Preferably, select someone who already has some context about this

[c-koehl]

@gplssm I'm done with the implementation, but it seems like I don't have the rights to select a reviewer or labels. I don't know what I'm doing wrong? Also I cannot tell, which reviewer is the best to choose

[gplssm]

@gplssm I'm done with the implementation, but it seems like I don't have the rights to select a reviewer or labels. I don't know what I'm doing wrong? Also I cannot tell, which reviewer is the best to choose

I'm not too familiar with permissions granted to individual devs. Maybe @uvchik can help out here.

Meanwhile, I can request a review for you. Did you talk to anyone before/during your implementation of "schedule for flow"? I would prefer to select this person then.

[c-koehl]

@gplssm I'm done with the implementation, but it seems like I don't have the rights to select a reviewer or labels. I don't know what I'm doing wrong? Also I cannot tell, which reviewer is the best to choose

I'm not too familiar with permissions granted to individual devs. Maybe @uvchik can help out here.

Meanwhile, I can request a review for you. Did you talk to anyone before/during your implementation of "schedule for flow"? I would prefer to select this person then.

@gplssm I actually didn't talk to anyone. I would suggest a reviewer with mathematical optimization knowledge, but I think my procedure is also comprehensible for non mathematicians.

[gplssm]

I've requested a review by @simnh because he's quite deep into mathematical modeling in oemof.solph. @simnh please re-request a review by someone else if you can't do it.

[uvchik]

@simnh Is this ready to merge?

@c-koehl Do you have a good example. I think it is a good idea to publish an example on oemof-examples to make this feature more visible.

[c-koehl]

@c-koehl Do you have a good example. I think it is a good idea to publish an example on oemof-examples to make this feature more visible.

Yes I have a jupyter notebook example. I will create a pull request in oemof/oemof-examples.

[codecov[bot]]

Codecov Report

Merging #666 into dev will decrease coverage by 0.03%. The diff coverage is 90.90%.

@@            Coverage Diff             @@
##              dev     #666      +/-   ##
==========================================
- Coverage   92.15%   92.12%   -0.04%     
==========================================
  Files          13       13              
  Lines        1377     1397      +20     
  Branches      326      333       +7     
==========================================
+ Hits         1269     1287      +18     
- Misses         62       63       +1     
- Partials       46       47       +1     

Impacted Files	Coverage Δ
src/oemof/solph/network.py	97.29% <33.33%> (-2.71%)	:arrow_down:
src/oemof/solph/blocks.py	90.69% <100.00%> (+0.59%)	:arrow_up:
src/oemof/solph/components.py	91.58% <0.00%> (ø)

---

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[uvchik]

I fixed the conflicts caused by the restructuring of oemof.

Please check if everything still works as expected.

@simnh: This PR is related to this example: https://github.com/oemof/oemof-examples/pull/53

[simnh]

I checked the example it works as expected. So I think this is fine to merge. The exmaple can be cleaned up a little (pep8 etc.) However, I will suggest this in the other PR.

[uvchik]

I tried to understand this part:

if (
        len(self.schedule) != 0 and
        ((len(self.schedule_cost_pos) == 0 and
        not self.schedule_cost_pos[0]) or
        (len(self.schedule_cost_neg) == 0 and
        not self.schedule_cost_neg[0]))):
    raise ValueError("The penalty and schedule attribute need "
                     "to be used in combination. \n Please set "
                     "the schedule attribute of the flow.")

My guess: If schedule is set by the user, the user should also set schedule_cost_pos and schedule_cost_neg.

If len(self.schedule) != 0 is True which is necessary to raise the error the schedule is already set, but in the message it says: "Please set the schedule attribute of the flow.".

If the user have to set the schedule_cost_neg/pos parameters you should not set a default value, because a default value only makes sense for optional parameter.

[c-koehl]

I do not know how to un - fail these tests. I am not sure if they were caused by me... Please correct me if I am wrong