Experimental study on fault ride-through capability of VSC-based HVDC transmission system

For voltage-source-converter based high-voltage-direct-current (VSC-HVDC)transmission systems, fault ride-through (FRT) capability is a very important grid requirement in order to enhance its operational availability under an alternating current (AC) gridfault condition. Voltage sags during a short-circuit fault in power transmission lines can leadto fluctuations in the direct current (DC) link voltage of converter systems, and may inducereversed power flow and even trip a VSC-HVDC transmission system. A practical methodis developed in this paper for investigating FRT capability of VSC-HVDC transmissionsystem characteristics during a voltage sag event using experimental results from Smart Grid Laboratory. Symmetrical and asymmetrical voltage sag events with different remaining voltages are applied to an AC grid that lasts with a variable duration. The experimental waveforms of the two converter systems are recorded and analyzed in order to evaluate theFRT capability of VSC-HVDC transmission systems.