Reduced-order Model and Mechanism of Dynamic and Stability Issues for Equivalent Source-Load Two-terminal DC System in DC Voltage Control Timescale

This paper investigates reduced-order model and mechanism of dynamic and stability issues for equivalent source-load two-terminal DC system in DC voltage control timescale. The main contributions of this work can be drawn as: 1) A physical model has been proposed with a concise parallel circuit structure of resistor, inductor and capacitor for dynamic and stability analysis of dc voltage control timescale in equivalent source-load two-terminal DC system. 2) With this model, a reduced second-order characteristic equation has been derived for dynamic and stability mechanism analysis, which can provide clear and intuitive insight into system damping and oscillation frequency with system and control parameters. 3) In DC voltage control timescale, increasing the DC voltage control loop proportional gain will increase the damping, but reduce the damping oscillation frequency; increasing the DC voltage control loop integral gain will reduce the damping and increase the damping oscillation frequency; increasing the DC capacitance will reduce the damping and damping oscillation frequency. Comparison of eigenvalues between detailed small-signal model and reduced-order model and detailed simulation results based on PSCAD/EMTDC verify the analysis.