Analytically Quantifying the Impact of Strength on Commutation Failure in Hybrid Multi-Infeed HVdc Systems

The strength has a large impact on the commutation failure (CF) in hybrid multi-infeed HVdc (HMIDC) systems including both voltage-source converters and line-commutated converters. However, this impact has always been quantified by the simulation-based method in earlier works, which is very time-consuming and cannot lend the exhaustively theoretical perspective. Thus, in this letter, the mathematical expression of the CF immunity index as the analytical function of the hybrid multi-infeed interactive effective short-circuit ratio strength index is first developed based on the quasi-steady-state model of HMIDC systems. Thereafter, the developed expression is used for analytically quantifying the impact of the strength on the CF in a much more efficient manner with more sufficiently theoretical perspective compared to the simulation-based method in earlier works. Finally, the theoretical developments are validated by the experimental results of the hardware-in-the-loop platform based on a hybrid six-infeed HVdc test system.