Governor Models

Initialization

Governor Models Available

Simulating mechanical transients traditionally falls within the realm of stability programs, where the modeling detail is not as complete as in an electromagnetic transient program such as EMTDC.  For the duration of most transient simulation runs, the mechanical system can often be considered invariant, and users should make sure that a governor model is actually required before using it.

Governors are represented in PSCAD as dynamic transfer functions, and can be interfaced to a machine by either providing the input mechanical torque signal directly, or through interaction with a corresponding turbine model (depending on the governor type).  There are several pre-defined governors available in the PSCAD Master Library.  If none of these suit your needs, equivalent governor systems can be constructed by using combinations of the basic control 'building blocks' from the CSMF (Control System Modeling Functions) section of the PSCAD Master Library.

Initialization

The governor model is initialized by continuously resetting its internal storage locations in order to produce an output, which is exactly equal to the mechanical torque output of the synchronous machine.  The machine and governor can be initialized and released together through a governor input parameter called Gov/Turb Status => 0-Initialize;1-Normal, and corresponding synchronous machine output parameter Locked Rotor[0] <-> Normal[1] Transition.

Governor Models Available

Both hydro and thermal (steam) governors are available in the PSCAD Master Library.  These models support variable time step, and allow for initialization at any time (not necessarily at time = 0.0) through additional control inputs.

For further details on background theory for these governor models, see PSCAD references [1], [2] and [3].