The EMTDC program is structured to accept user-defined, external source code. This is accomplished by either linking to pre-compiled source, such as object or static library files, or by simply appending the source directly. Whichever means is chosen, the external source will be combined with all other project source during the compilation process; resulting in a customized executable program for running the simulation.
External source is incorporated through the use of component objects. Components are employed in PSCAD to represent system models; in fact, the entire master library project is composed of components. Some of these components are designed to insert source directly into the system dynamics (i.e. BEGIN, DSDYN or DSOUT), and/or provide information for constructing the electric network. Others link to subroutines imbedded within the EMTDC body of source, where intrinsic network and storage variables are manipulated directly to represent complex electrical devices, such as machines and FACTS. Components are fully customizable and may range from the very simple, which require just a few lines of code, to the very complex, represented by a combination of several functions and subroutines.
The component concept affords flexibility in simulation design, providing a graphical interface to both EMTDC and the PSCAD project compiler. This interface ensures that all possible aspects of the EMTDC program (customizable parts anyway) are fully accessible to the user. After all, this design environment is the same one used by both PSCAD and EMTDC developers alike.