In Gurobi, the quadratic constraints do not work, meaning the optimization results do not satisfy the specified squared term constraints

Answered

筱翊 黄

October 27, 2024 09:06

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Hi everyone,

 The natural-gas system satisfies the mass conservation law of fluid dynamics and Bernoulli equation in the operation.The gas flow of pipelines and gas pressure of gas nodes are
 interrelated which can be modeled as presented below.The optimization results satisfy the constraint related to pipeline gas flow (Constraint 1), but do not satisfy the pressure-related squared constraints (Constraint 2).

%Constraint 1 is as follows:
for t = 1: n_T
    C = [C, GasFlow(:,t) == (G_yY_in(:,t) + G_yY_out(:,t)) / 2];
end

%Constraint 2 is as follows:
for i = 1: n_GasBranch
    f_bus = GasBranch(i,2);
    t_bus = GasBranch(i,3);
    for t = 1: n_T
        C = [C, GasFlow(i,t)^2 == Cij(i)^2 * abs(GasPressure(f_bus,t)^2 - GasPressure(t_bus,t)^2)];
    end
end

Related to

• Wrong Result

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• Official comment

  

  Simranjit Kaur

  • Gurobi Staff

  November 13, 2026 01:09 Edited

  This post is more than two years old. Some information may not be up to date. For current information, please check the Gurobi Documentation or Knowledge Base. If you need more help, please create a new post in the community forum, or try Gurobot, our chatbot interface offering instant, expert-level support.
• 

  Ryuta Tamura

  • Gurobi Staff

  October 28, 2024 04:36 Edited

  Hi,

  This article might help: How do I diagnose a wrong result?
  Also, I suggest you start by sorting out what the current situation is. For example:

  • What constraints are you trying to write?
  • What values do the variables take in the solution you want?
  • What is the actual solution obtained and how does it differ from the desired result?

  In addition, it may be useful to export the model to an LP file to verify that the model is constructed as expected. How do I export a model from Gurobi?

  Thanks,
  Ryuta

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