Reduction of the DC Circuit Breaker Requirements by Bidirectional Solid-State Fault Current Limiter in DC Grid

Abstract

Reliable and economic protection of DC grids against fault currents is the main challenge for the development of voltage source converter-based DC grids. Application of fault current limiters (FCLs) can limit the rapid increase of fault current and reduce the DC circuit breaker (DCCB) requirements to isolate the fault. This article reports a bidirectional solid-state FCL (BSSFCL) to protect the DC lines against DC short circuit fault. In addition, it can limit fault current in both directions. The circuit and principle operating of the proposed BSSFCL are presented. Then, the current limiting performance of the proposed BSSFCL is analyzed and its parameter design requirements are presented. Finally, the performance of the proposed BSFFCL is compared with that of the RL-current limiting circuit (RL-CLC), mutual inductance-type FCL (MIFCL), and restive mutual-inductance solid-state FCL (RMI-SSFCL). The numerical analysis and simulations were done using the PSCAD/EMTDC software. It was found that, the BSSFCL could effectively enhance the breaking capability of DCCBs. Moreover, it outperforms the RL-CLC, MIFCL, RMI-SSFCL in terms of the fault current limiting, the fault clearing time and metal oxide arrester (MOA) energy absorption of DCCBs.