Dynamic control modelling of a bipole converter station in a multi-terminal HVDC grid

Awareness concerning the global warming and environmental issues has been a trigger to expand the utilization of renewable energies replacing electricity from fossil fuels. The deployment and integration of cleaner and eco-friendly generators to the power system has been one of the primary drivers to develop technologies associated with High Voltage Direct Current (HVDC). Monopole and bipole converter stations can be controlled by different control modes based on voltage and power. In DC voltage control, a traditional method to calculate DC voltage error in monopole converter uses voltage average between positive and negative terminals of the Voltage Source Converter (VSC). Aforementioned method cannot be applied to bipole converter station due to one terminal in each converter is grounded, consequently, a new approach is proposed which uses a voltage difference as feasible solution. Additionally a complete dynamic control modelling is tested in CIGRE B4 DC Grid developed in DIgSILENT PowerFactory. Results depict an accurate model which can be used to perform a variety of electrical studies in order to prove the feasibility of Multi-Terminal HVDC projects.