The EMTDC solution engine consists of two main parts: The System Dynamics, which includes the master dynamics subroutine (DSDYN), the output definition subroutine (DSOUT), and the initialization subroutine (BEGIN); and secondly, the Electric Network Solution.
Figure 2-1 - Core EMTDC Solution Process
An EMTDC simulation begins at a specified start time and finishes at a specified end time. Between these two times, the program performs the same sequential process iteratively, each iteration incrementing the time by a specified interval. This interval is referred to as a time step, which remains constant (i.e. fixed) during the course of the simulation.
As illustrated by Figure 2-1, the core solution process begins and ends with the system dynamics. First, variables are initialized and stored in BEGIN. Dynamic functions are performed in DSDYN, which includes the preparation of electric network devices such as sources, etc., as well as the manipulation of control signals. The electric network is solved and the resulting measured quantities are considered, along with any post-solution processing requirements, in DSOUT, before the time step is incremented.
Of course, the complete EMTDC solution sequence is more involved than that shown in Figure 2-1. There are several other features present that ensure solution accuracy and speed; all of which are discussed in the following sections. A more complete program process is illustrated in Figure 2-2.
