Report sections of the optimizer output log

Optimization solver

This section of the output log displays the nonlinear optimizer that AVEVA Process Simulation used to solve the optimization set. The software supports two types of nonlinear optimizer:

• OPERA + Feasible Path (Default) - The OPERA optimization solver requests AVEVA Process Simulation to search for a feasible solution during every optimization iteration. This provides a more robust solve, but can result in slower runtime.

• OPERA – OPERA simultaneously closes constraints and optimizes. This is computationally cheaper, but less robust.

  

You can use the OptimizationMethod option in the Optimization Settings model from the Settings Library to select the nonlinear optimizer.

Note: The Settings Library is an example Model Library distributed with AVEVA Process Simulation. You can import it from the %userprofile%\My Libraries\Examples folder.

Optimizer options

This section displays the following information related to the nonlinear optimizer:

• Trace Level – The verbosity of the optimization trace report. AVEVA Process Simulation adds the optimization trace report information to the %LocalAppData%\SimSci\SimCentral\Logs folder along with the other AVEVA Process Simulation log files.

• Max Optimization Iterations – The maximum optimization iterations allowed before stopping the solver.

• Initial Hessian Diagonal Matrix – The initial value in the diagonal elements of the Hessian matrix.

• Objective Tolerance – The convergence tolerance for the objective function.

• Constraint Tolerance – The convergence tolerance for the constraint closure.

  

You can find and update these options by using the Optimization Settings model from the Settings Library.

OPERA Problem Summary

This section outlines the optimization problem that the Optimizer is trying to solve.

OPERA Iteration Summary

This section displays high-level information for each OPERA iteration. It includes:

• Iteration Number – The current optimization iteration.

• Objective Value – The value of the objective function at the current iteration.

• Constraint Closure – The residual of the equality constraints at the current iteration.

• Step Fraction – The fraction of the overall step taken at the current iteration compared to the previous iteration.

• Active Bounds – The number of process variables that are currently at their bounds.

• Iteration Time – The time taken to complete the current iteration.

The last column of this section is not labeled. It contains high-level information on the search direction, where o represents the original OPERA search direction and c represents a correction in the search direction by AVEVA Process Simulation. Additionally, a ->s indicates a reevaluation of the Hessian matrix due to difficulty in closing the iteration.