Research on Fault Characteristics Analysis and Location Method of the AC-DC Hybrid Renewable Distribution Network

The multi-terminal AC/DC hybrid distribution network is a complex system composed of many power electronic devices. Its diverse and comprehensive fault characteristics are characterized by multiple cycles and strong transients. In this paper, the characteristics and mechanisms of typical DC short-circuit faults based on modular multilevel converter (MMC) systems are studied first. In order to achieve reliable and fast location of MMC short-circuit faults, a fault location method combining network topology protection and longitudinal protection based on cosine similarity is proposed in this paper. The validity of the proposed method is verified by simulation of its MV-DC side faults.