Fault Current Suppression for the Fault Ride-Through of Triple-Active-Bridge Converters

The fault ride-through (FRT) capability is an important ancillary service for power converters in dc power distribution systems. Despite extensive research, the triple active bridge converter (TABC) has been perceived as lacking FRT capability due to the requirement of blocking all power switches in the event of a dc short-circuit fault at the dc terminals. This study analyzes the dc short-circuit characteristics of TABCs in worst-case scenarios, which cover the dc side and the internal current stress under fault transients and steady-state conditions. Based on the analysis, this study proposes an optimized dual phase shift control scheme to enhance the FRT capability of TABCs. This scheme enables TABCs to continue operating under dc fault conditions, ensuring uninterrupted power output while minimizing current stress on the fault side. Moreover, the post-fault operations of TABCs for both temporary and permanent faults are discussed. TABCs can operate in the two-port mode following the circuit breaker actuation. The effectiveness of the proposed method is validated through simulation and experimental verifications.