Energy Release Device for Solving Power Surplus Problem in LCC-VSC Hybrid Cascade Multi-terminal Transmission Project

LCC-VSC hybrid cascaded multi terminal HVDC transmission system has significant advantages in reducing multi-infeed DC commutation failure and improving multi terminal power supply reliability. However, the hybrid cascaded DC system has a significant problem: when the receiver system fails, the surplus power of the hybrid DC system will lead to overvoltage and overcurrent of the receiver VSC. Aiming at the power surplus problem of LCC-VSC hybrid cascaded multi terminal HVDC transmission system, this paper proposes a scheme of installing controllable arrester at the receiving end as the energy release device, and analyzes the characteristics of the energy release device under various fault conditions of the hybrid DC system, which is verified through PSCAD/EMTDC simulation.