Supplementary Damping Control of PSS and HVDC-SDC for Low-Frequency Oscillation Suppression in AC/DC Inter-connected System

Aiming at the problem of low-frequency oscillation in AC/DC inter-connected system, this paper deduces the mechanism of HVDC supplementary damping controller (HVDC-SDC) to enhance the damping of power system, and establishes the low-frequency oscillation suppression scheme in AC/DC inter-connected system. By analogy with the mechanism of power system stabilizer (PSS), this paper explains the mechanism of HVDC-SDC using the change of stator current to add damping torque for the generators. The correctness and feasibility of the mechanism is verified in AC-DC inter-connected system with mechanism derivation and simulation verification. The scheme of low-frequency oscillation suppression in AC/DC inter-connected system suitable for different power flow directions is built with both advantages of PSSs and HVDC-SDC to better improve the dynamic stability of power system.