Engee documentation

Physical variables

Physical variables variable viewer icon - is a Engee tool that helps to check initial conditions and target values of models.

The physical variables window allows you to see which target values of variables have been met at the block level, and also displays the priorities and target values of variables (if specified).

The physical variables window serves as an analytical tool for displaying data and does not provide the ability to manipulate variables, their priorities and values. To interact with variables directly, open the parameters window of the corresponding block.

To open the physical variables window, click the variable viewer icon button in the working area of the model. By default, the physical variables window does not contain any data:

variable viewer 1

To start working with the physical variables window, open settings window debug article icon 1 and in the tab Debugging enable the option Results of physical variables initialization:

result saving 1

Interface

The physical variable window interface is a table that lists all physical variable blocks and all their available variables. The table provides information about the initialisation status, priority, target and actual initial values, and other characteristics for each physical variable:

variable viewer 2

The physical variables window consists of the following columns:

  1. Name - contains the full names of all variables used in the model. The names indicate the block (e.g. Voltage Sensor), its connection port (e.g. p or n), and the physical characteristic measured at that point (v for voltage or i for current);

  2. Status - the current status of the variable is indicated, showing whether the variable has been successfully initialised or, for example, whether there are errors in its value. There are three statuses in total:

    • variable viewer 3 - is displayed for variables whose initialisation goals have been achieved and for all variables with no set priority;

    • variable viewer 5 - indicates variables with low priority if their initialisation goals have not been achieved;

    • variable viewer 4 - is displayed for variables with high priority if their initialisation goals have not been met.

  3. Priority - displays the priority assigned to the variable (if set). By default None. The priority may affect the order in which variables are processed during calculations (see here for details);

  4. Target - indicates the target value of the variable (if set);

  5. Start - displays the actual initial value of the variable calculated by the solver after initialisation of the model. This value is used at the initial moment of time for modelling;

  6. Unit - specifies the units of measurement of the variable. This helps to interpret numerical values in a physical context;

  7. Eliminated - a tick in this column indicates that the variable has been excluded from the calculations prior to numerical integration. These variables do not participate in the solution of the system, and their preliminary initial values do not affect the result;

  8. Determined - a tick in this column indicates that the value of the variable depends on the input data of the system or is predetermined on the basis of equation analysis. Setting priority and target values for such variables usually does not affect the system solution. If you set a high-priority target for a predefined variable, the solver will probably not be able to achieve it, but will spend additional time trying to find an alternative solution;

  9. Differential - a tick in this column indicates that the system equations contain time derivatives of the variable in question (its rate of change over time). Such variables often require high priority during initialisation, as their initial values noticeably influence the system behaviour during simulation;

    Differential variables play an important role in simulation as they add dynamic behaviour to the system and can create independent time-dependent states.

  10. Pre start - contains the value of the variable set by the user in the block settings before running the model. This value serves for the initial setting of variables in the preparation stage of the simulation.

    Do not confuse the Start and Pre-Start columns:

    • Pre-Start is the initial value set by the user in the block settings;

    • Start is the value calculated by the solver after the model has been initialised.

To sort, click on the desired column with the left mouse button:

variable viewer x 1

Variables can be filtered by name:

variable viewer x

Update button update button 1 - recalculates the initial conditions for the model and updates the values displayed in the physical variables window. Use this button after adjusting block parameters values, changing priorities and targets of variables, or rebuilding the model.

Panel Diagnostic*where the overall status of the variables is displayed. For example, the phrase "All variables received" with the icon variable viewer 3 means that all variables have been successfully initialised and are ready for operation. As with the *Status (variable status) column, three statuses are available:

  • variable viewer 3 - all variables received;

  • variable viewer 5 - all high-priority targets have been completed, but some low-priority targets have not been completed;

  • variable viewer 4 - it is impossible to receive all high-priority variables, not all high-priority targets are fulfilled.

The number next to the filter icon filter icon 1 shows the current number of sorted variables.

Interaction with model updates and simulations

Useful features of the physical variables window:

  • Re-opening the physical variables window does not trigger its automatic update. For complex models, calculating initial values for all variables can take some time, and unnecessary updates can cause loss of performance. Therefore, the update button is used to update the data update button 1;

  • When you open the physical variables window, it displays the data from the last simulation;

  • If you run the simulation again, the data will be updated automatically when the physical variables window is open;

  • If you change priorities, variable targets or block parameters, the data in the physical variables window is not automatically updated.

  1. Physical Modeling

  2. Customising physical blocks using target values

  3. Model building