A New Hybrid DC Circuit Breaker Based on Thyristors

In response to the grand goal of “carbon peaking and neutrality”, it is imperative to accelerate the development of flexible DC transmission technology. The hybrid DC circuit breaker (DCCB) is a key device to ensure the safe operation of the flexible DC power grid, and is used to realize fault isolation on the DC side. However, in most of the existing topologies, IGBTs are used as switching elements, which are costly and technically difficult. Therefore, a new hybrid DCCB based on thyristors is proposed in this paper. The circuit breaker mainly uses thyristors instead of IGBTs to switch the circuit state, which greatly reduces the cost and technical difficulty. In addition, the circuit breaker also has the functions of pre-charging and adaptive reclosing, which lays a good foundation for the large-scale application of the circuit breakers. Moreover, a detailed analysis and theoretical derivation of the working process of the proposed circuit breaker is carried out. Simulation models of single-ended equivalent and four-terminal DC power grids are built in PSCAD/EMTDC. The proposed circuit breaker is analyzed and verified in the simulation models, and the performance is compared with the typical circuit breakers. The simulation results verify the feasibility of the proposed circuit breaker and show that, on the basis of similar performance, the cost of the proposed DCCB is greatly reduced compared with the typical DCCBs. © 2022 Science Press. All rights reserved.