Modeling of VSC-HVDC and control strategies for supplying both active and passive systems

An equivalent continuous-time state-space model for VSC-HVDC in the synchronous dq reference frame has been established in the paper. Based on the model, relevant control strategies have been developed for the cases of supplying active and passive systems. The multi-input multi-output (MIMO) control schemes are emphasized in designing power controller and voltage controller. The scheme features feed forward compensation to decouple the d- and q-axis of the voltage source converter (VSC) model, which ensures the independent control of active and reactive power, DC voltage and reactive power as well. Simulations have been performed on PSCAD/EMTDC, a visual design environment for power system studies. The validity of the mathematic model and the feasibility of the control strategies have been proved by the simulation results