Dealing with large AC systems interfaced with DC grids through converters poses new challenges on simulation platforms. A linearized model is essential for many common control design procedures while various converter control mode implementations are required to emulate different operating conditions in the DC grid. Currently many of the domain specific tools are unable to provide such linearized model when the model contains DC Grid components. To overcome this limitation of the domain specific simulation platforms, it is proposed to use the general purpose modeling language Modelica and the tool Dymola to generate linear models to develop extensions for controller design while PowerFactory Digsilent is used for time domain simulations. In this way it is possible to validate the actual system performance of the controller which is designed based on the linearized model. In this paper VSC HVDC is considered for the DC grid.