An impedance-based approach to HVDC system stability analysis and control development

High-voltage dc (HVDC) transmission system stability has traditionally been studied using state-space models and eigenvalue analysis. The state-space approach requires design details of each component of the HVDC grid, which is usually not available, and does not support local control development at individual terminals. This paper presents an impedance-based approach to HVDC system stability analysis that is easier to apply and supports local and adaptive control development. Representation of a HVDC system by an impedance equivalent circuit is presented first. Analytical impedance models are then developed for different HVDC converters to support system impedance analysis. The ability of impedance-based analysis to predict and mitigate different control and system instability problems are demonstrated and verified by detailed circuit simulation.