An Equivalent Single-Infeed Model of Multi-Infeed HVDC Systems for Voltage and Power Stability Analysis

In this paper, an equivalent single-infeed model of a multi-infeed HVDC system is derived to lend theoretical basis for defining an index called equivalent effective short-circuit ratio (EESCR), which can resolve the ambiguity when applying the effective short-circuit ratio (ESCR) concept for the single-infeed to multi-infeed HVDC systems. Moreover, a Critical EESCR is derived analytically from the equivalent model as stability boundary of the multi-infeed HVDC system. The EESCR is also compared with other indices proposed recently to clarify their empirical or heuristic assumptions. The CEESCR stability boundary for a practical multi-infeed configuration is derived and verified by time-domain simulations to demonstrate the validity of the theoretical developments.