Project Commands
From SysCAD Documentation
Navigation: User Guide -> Menu Commands -> Project Commands
This section shows the Project Commands in SysCAD 9.2. Refer to Project Commands in 9.1 for SysCAD 9.1.
Contents |
Settings
Connections Tab Page:
Please refer to Data Sharing for more information.
Historian Tab Page:
Please refer to Setting Up in Historian section for more information.
ProBal Setup
Command Path Project, ProBal Setup
This command will only be available in a ProBal project.
NOTE: SysCAD must be stopped for this command to be accessed.
This will open the Solver Dialog box:
Convergence
The user may define the maximum number of iterations that SysCAD will perform before automatically halting. The maximum number of iterations allowed is 20000.
Changing the Relative (Rel) and Absolute (Abs) Tolerance can vary the accuracy and speed of the solution. By increasing the numbers the solution will converge faster, but will be less accurate.
A tolerance calculation is performed every iteration, for all species and heat flows in all units/links. See Tolerance Testing for more information.
The SysCAD model is considered converged if the calculated tolerance is less than or equal to 1.0 for all species and heat flows in all units/links for the last n consecutive iterations, where n = Rqd Converged Iters, as set by the user.
Changing the relative tolerance from 0.01 to 0.1 would increase the error margin by an order of magnitude.
Typically the relative tolerance would be greater than or equal to the absolute tolerance used.
The Method of solution can also be changed. Options available to the user are Direct Substitution, Adaptive Direct Substitution, or Wegstein Acceleration. For more information on convergence/tolerances, please refer to Tear Blocks.
Active Pages
You can Activate or Deactivate flowsheets (Graphics Windows) in the SysCAD Project by selecting the flowsheet and pressing the appropriate buttons. When a Graphics Window is deactivated, all models on that graphics page will become inactive, thus not included in the solution. Any connections with other graphics pages will be disconnected (done in the Feeder/CrossPageConnector model). The user should check all feed and product streams when solving a simulation with deactivated graphics to ensure correct information is used.
This is not available if the drawing is not loaded in the Graphics Window.
Options
The Keep Status Display Pinned option displays the Solver Status dialog box.
The Reset option will re-initialise SysCAD variables at the first iteration. Refer to Actions Commands - Complete Reset for more information.
By default, all of these options will be off.
Dynamic Setup
| Command Button | 
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| Command Path | Project - Dynamic Setup |
NOTES:
- This command will only be available in a Dynamic project.
- SysCAD must be stopped for this command to be accessed.
This command will allow the user to change the dynamic simulation options, such as solving method, step sizes and so on prior to running the SysCAD dynamic simulation. These are done through the Dynamic dialog box. When the settings have been changed, press the OK button to save the new settings and close the dialog box.
Time
A number of options are available for controlling how long a dynamic simulation must run or solve for. These are: 'forever' where the solver never stops; 'to steady state' where solver runs until it detects there are no more changes in the process variables; 'for' a specified time span; 'until' a specified end time; 'for x steps' runs for a specified number of steps. The current time is shown, user can choose to synchronise the time with clock - NOTE this will automatically put your simulation into Real time, thus project cannot run in accelerated time option.
If Synchronise with clock option is NOT selected, user can choose to run the project in real time, solver will determine to speed up or slow down the simulation to meet with the real time clock.
Another option the user can choose is to have the simulation run in accelerated time, this is done by specifying a Real time multiplier, thus a real time multiplier of 8 will mean SysCAD is running 8 times faster than real time.
For users that would like to run the simulation as fast as possible without having to relate to real time, make sure the Real Time box is NOT selected, and then set the iteration and step size option on the Method's tab.
Method
The method used for the dynamic simulation can be changed here. The methods available are Euler, Runge-Kutta2 and Runge-Kutta4.
SysCAD solves the dynamics of a flowsheet in incremental time steps. The step size can be fixed or variable, depending on the integration method used. Only the Runge-Kutta4 allows variable step sizes.
- Fixed iteration size
The iteration size is fixed. The higher value results in faster relative speed, but less accurate solution. The maximum meaningful fixed iteration size that can be used is dependent on the dynamics (relative flow rates, volumes of units etc) of the process.
- Variable iteration size
With a variable iteration size the user defines the maximum and minimum iteration sizes. SysCAD uses a iteration size between these limits and aims to use the largest possible. The iteration size used is dependent on the dynamics response of the process. If changes are occurring rapidly or a significant change occurs (valve opened, tanks overflows) when SysCAD is solving the model, the iteration size is reduced until conditions have stabilised.
Once conditions have stabilised or the discontinuity has been passed, the iteration size is increased again.
A variable iteration size solution gives the most accuracy.
- Tolerances
The Relative and Absolute Tolerances can be set. The smaller the tolerance the more accurate the result, however, this will also slow down SysCAD considerably. Refer to convergence in ProBal Setup.
- Step size
A step size determines how often the values are updated in SysCAD. A step can be made up with multiple iterations. In the example above, the iteration size is 0.2 sec, and the step size is 1 sec, that is, each step is made up with 5 iterations. Number displays in trend windows and so on will be refreshed (or stored in historian) at the end of the step.
Network
This tab page contains the solution network settings. These can be used to improve the SysCAD speed in obtaining a solution.
Link Convergence
- Absolute Tol - The absolute tolerance required for the solution. If this value is increased, then the model will solve faster, but will be less accurate.
- Relative Tol - The relative tolerance required for the solution. If this value is increased, then the model will solve faster, but will be less accurate.
Network Convergence
The DeTuning parameter is used for convergence of the network.
Spill Area
For a dynamic simulation, if a tank overflows, it needs to go to an area. By default it will go to the Global Area, but if the model has other areas defined then the user may specify a different area where spillages will report.
Tears
- A tear is required to solve models that contain one or more recycle streams.
- SysCAD determines the optimum position for the tears using the algorithm described in the following paper:
- Ollero P. and Amselem C., "Decomposition Algorithm for Chemical Process Simulation", Chem. Eng. Res. Des., 61, 303, (Sept. 1983)
- SysCAD determines the position of the tears as part of the startup sequence each time the model is solved.
Criteria
- Max Iterations - The maximum number of iterations that SysCAD will perform in each step in order to solve iterative problems.
- Rel Tolerance - The relative tolerance used for iterative problems.
- Ads Tolerance - The absolute tolerance used for iterative problems.
Method
The user may choose any of the following methods:
- Direct Substitution;
- Adaptive Direct Substitution; or
- Wegstein Acceleration
Please see Convergence Methods for a description of these different methods and the Damping Factor.
Active Pages
You can Activate or Deactivate flowsheets (Graphics Windows) in the SysCAD Project by selecting the flowsheet and pressing the appropriate buttons. When a Graphics Window is deactivated, all models on that graphics page will become inactive, thus not included in the solution. Any connections with other graphics pages will be disconnected (done in the Feeder/CrossPageConnector model). The user should check all feed and product streams when running a simulation with deactivated graphics to ensure correct information is used.
This is not available if the drawing is not loaded in the Graphics Window.
Start Options
Startup Reset Actions:
| Process | This will empty all pipes and flow values when the run begins. Default is off. |
| Control | This will reset all controllers back to 'Base' state, i.e. the same state as when the controller is first inserted into the project. This is mainly relevant for PID controllers. Default is off. |
| Statistics | Selecting this will Reset the Statistical blocks when scenario is started. Default is on. |
| Events/Profiles | This will reset all Event and Profiles back to start time. Default is on. |
| Empty | This Empties all containers with surge, e.g. Tanks. Default is off. |
| Preset | This resets all tanks that have the 'Preset.On' button ticked and have Preset data. Default is off. |
Please also see Startup Reset Actions on the Dynamic Configuration access window, Action Commands in the Plant Model access window and Actions Commands for more information.
Date and Time:
The user may enable Set Time at Start and then set the starting time for the simulation.
Historian:
- Restart Historian at Start: This option clears any old data in the historian at the start of the simulation.
Update Behaviour
Find Changes
This is the same as the Compare Projects command described below except that it is used to compare the currently loaded project to the saved version of the same project. Therefore, the user does not have to choose which projects to compare.
Compare Projects
NOTE: This command is not available while SysCAD is solving or running.
This command allows the user to compare two projects for its differences in tags and values. It is most useful to highlight changes in projects such as adding or deleting of unit operations or different operating conditions.
When the command is activated, it opens the Compare Projects Dialog box:
- Choose the projects to be compared by using the browse buttons.
- Select the comparison options
- Press Compare when ready to start the comparison
- SysCAD will display the differences between the projects in the dialogue box, as shown above.
- To see the results in Excel, click on either the Copy All or Copy List buttons and then paste the result into an Excel file.
- Copy All will contain all details of the projects, time and the differences.
- Copy List will only contains the differences between the projects.
Another similar command is Compare Scenarios
