Dynamics

Signal Storage

Signal Flow

Buses

Unit System

The properties contained within the Dynamics section are related to the EMTDC system dynamics.  These are explained below.

Signal Storage

The input parameters involved here are outlined below.

Store Feed Forward Signals for Viewing

When this control is enabled, all declared data signal variables (be they feed-forward or feed-back signals), will be transferred to and from their designated EMTDC storage array each time step.  If this control is disabled, only those declared variables that must be transferred to storage (such as feed-back signals) are considered; all other variables are deemed temporary and are discarded at the end of each time step.

NOTE: It is important to note that tool tips (flybys extract the value of the signal being monitored from storage.  Therefore, if this control is disabled, all feed-forward signal values will not appear in the tool tips!

In smaller projects, toggling this control will have very little effect on the simulation speed.  As projects become larger and contain many control signals, this feature may help to speed things up.

EXAMPLE 7-3:

In the simple control system shown below, there will be a total of four, type REAL variables declared in the project Fortran file when this project is compiled: In1, error, Out and In2.  Three are feed-forward variables (indicated by the symbol), and one is a feedback variable (indicated by the symbol).

NOTE:  Users can display these symbols at any time by enabling the Show Signal Locations parameter in the Module Settings dialog.  For a more detailed description of these symbols, see Show Signal Locations in Chapter 11 of this manual.

If Store Feed Forward Signals for Viewing is enabled, all four of the above variables will be stored every time step, as indicated in the following excerpt from the project FORTRAN file:

If Store Feed Forward Signals for Viewing is disabled, only the feedback variable Out will be written to storage every time step as indicated in the following excerpt from the project FORTRAN file:

Signal Flow

The input parameters involved here are outlined below.

Compute and Display Flow Pathways on Control Wires

Select this option to show signal flow direction on control signal Wires (i.e. Wires carrying REAL, INTEGER or LOGICAL data types).  See Control Signal Pathways for more details on this.

Buses

The input parameters involved here are outlined below.

Treat Multiple Buses with Matching Names as the Same Bus

Select this option to treat multiple buses with the same name as the same bus.  That is graphically separated bus points with the same name will represent the same EMTDC node points in the electrical grid.  See the Bus component for more.

Unit System

The input parameters involved here are illustrated below:

Enable Unit Conversion and Apply to Parameter Values

Select this option to enable the Unit System.  

NOTE:  Enabling the Unit System may cause compilation failures in previously created case projects.  This is normally due to input parameter units in existing components that are not recognized by the Unit System compiler.  If compilation failure does indeed occur:

1. Consult the Output Window for error messages:  Point to the error source by Locating the Problem Source.

2. View the parameters of the component.

3. Scan through the Value column and look for a #NaN (Not a Number) symbol.  This usually indicates that the entered unit does not match the Target Unit defined for this input parameter.