A Novel Integrated Protection for VSC-HVDC Transmission Line Based on Current Limiting Reactor Power

In this paper, a novel integrated protection for VSC-HVDC transmission line is proposed. The protection scheme includes a main protection and a backup protection. The main protection is based on current limiting reactor power (CLRP), while the backup protection is based on variation tendency of current. The changing characteristics of CLRP and current are theoretically analyzed under different fault conditions. Based on the characteristics, internal and external faults of DC transmission line can be identified. Then criteria of the novel integrate protection can be built. The main protection can detect the faults quickly without communication, while the backup protection is used to identify the high resistance faults and provide a backup if main protection fails. The scheme not only protect the whole transmission line without dead zone, but also improve the speed of protection with simplified algorithm. A typical VSC-HVDC system is modeled using PSCAD/EMTDC. Comprehensive simulations is done to verify the performance of proposed scheme. Furthermore, the protection does not require a high sample frequency and does not require data synchronization. These make it valuable for application in practical VSC-HVDC transmission system.