The renewable generator has the following models
1. REGCA1- Generator model
2.REECA1- Generator electrical control model
3. REPCA1- Plant controller model
Other two models are aerodynamic model and drive train model for wind machines.
The electrical control model pertains to the electrical control of an individual renewable machine . With this model we can control the active and reactive power, voltage and power factor of the machine.
REPCA1 is plant controller model and it controls the P,Q,V and pf depending upon the status of control flags.
The machine (s) can ,if modeled for voltage contro,l control the terminal bus or a remote bus.
Usually the plant controller control the voltage at a remote bus (HV or MV).
Use proper flags and bus numbers in REECA1 and REPCA1 along with gains and time constants for achieving this.
More info, such models, load flow model configuration and suspect states if any, is required for answering the second question.
Hope this helps.