An oscillation suppression strategy for hybrid DC systems based on virtual resistance

Hybrid DC transmission systems are prone to DC current oscillations as the parameters of constant DC current controller increase， an oscillation suppression strategy based on virtual resistance is proposed. This strategy generates an additional voltage that is in phase opposition to the disturbance component by leveraging the current oscillation component and an introduced virtual resistance， thereby achieving suppression of the DC current oscillations. Initially， a small-signal model of the hybrid DC transmission system is established to analyze the impact of parameters of the constant DC current controller on the stability of small signals. Subsequently， an oscillation suppression strategy based on virtual resistance is put forward to study the influence of virtual resistance on the stability of small signals in the system. The effectiveness of the proposed strategy is verified through PSCAD/EMTDC simulations. Lastly， the stability range of the virtual resistance under different constant current controller parameters is analyzed. The research findings indicate that the proposed control strategy can effectively eradicate DC current oscillations and improve system stability.