It is not possible to change the voltage set point of an external grid during a simulation. The workaround is to replace the external grid with an AC voltage source (ElmVac) and then use one of the following approaches:

- define a parameter event for the ElmVac using one of the available input signals, Ul0 (line-line voltage in kV), u0 (voltage in p.u.), or U_A/B/C  (Voltage phase A/B/C in kV) to change the line-line voltage set point. It is necessary to specify which input signal shall be used for the parameter event in the ElmVac - Simulation RMS page, Advanced tab.

- define a dynamic model (using either DSL or Modelica) to apply the desired change to the voltage setpoint. The model should be connected to one of the available input signals of the ElmVac.