The class implements a model of a simple proportional governor with saturation.
If fixInitialControlledVariable = true
, an initial equation is added to ensure that the mechanical power output PMechPu
is equal to its start value PMechPuStart
. In order to fulfill this condition, the initial value of the reference signal should be free, so that the Modelica tool can back-compute it automatically. For this purpose, the PowerGrids.Controls.FreeOffset block should be used to generate the reference signal to be connected to the VrefPu
input.
In case the condition PMechPu = PMechPuStart
cannot be fulfilled without violating the controller saturations, then an alternative initial condition is enforced, which prescribes the saturation block input so as to obtain a certain degree of oversaturation oversaturationPu
. This allows to back-compute a unique initial value of the reference signal, which is of course dependent on oversaturationPu
and hence somewhat arbitrary.