MODELGUY's profile - activity

@perlofi, for GGOV1 Pref can not be zero in isoch mode it should be 1.0. You should read my explanation by looking at GGOV1 block diagram and understand that Pref is speed/load reference. In PSSE when GREF is set to zero, internally software may be making Pref = 1.0 to simulate isoch mode.

@perolofi. Gref is governor reference, which is generic term applicable for all governor models. In case of GGOV1 model, the Gref should be same as Var L which is Pref signal shown in the block diagram. When droop is zero, Speed = Pref and logically to drive speed to 1.0pu, Pref should be 1.0pu.

Change VAR L - Load Reference to 1.0 at the same time when you make ICON RSELECT = 0 to enable ISOCH mode. This should regulate the speed to 1.0 pu.

The GAST2A model was developed in the 1980’s to represent old GE turbine controls (MKII to MKIV). Since that time, the turbine controls have evolved to include a governor with a proportional-integral controller and droop developed with electrical power as the feedback signal. Also, significant changes have been made to the gas turbine design to improve performance. The GAST2A model is not recommended for use for modern gas turbine installations.

The GGOV1 model was developed as a general purpose turbine-governor model to be used for dynamic simulation studies. GGOV1 is appropriate for studies where the plant remains connected to a large grid; that is for all conventional grid interconnection studies. The model can also be used for load rejection studies to simulate the system response to loss of loads. For large load pick up studies (e.g. black start) the model may not provide accurate results since guide vane dynamics, are not included in the GGOV1 model.