Multiple Infeed Short Circuit Ratio -Aspects Related to Multiple HVDC into One AC Network

The paper suggests an extension of the classical definition of Short Circuit Ratio and Effective Short Circuit Ratio to multiple infeed of HVDC transmission configuration. With such new indexes, which consider the interaction between converter stations, it is possible to predict low frequency resonances, dynamic overvoltages and risk for voltage and power instability at low value of the index, similar to single infeed configuration. In this paper it is also discussed other relevant issues related to integration of multiple HVDC links when the strength of the system is relatively low compared to the amount of power delivered by the HVDC links.