Bridge-Type Multiport Fault Current Limiter for Applications in MTdc Grids

Since the dc-side fault in the multiterminal dc grid propagates extremely fast, the fault current limiter (FCL) is essential to achieve fault ride-through of the healthy network. Current-limiting inductors (CLIs) are currently the most commonly used FCLs in projects that have been built, are under construction, or are planned. The CLIs can be designed based on the system requirements, such as converter fault ride-through and dc circuit breaker (DCCB) interrupting capacity. Unfortunately, the installation of CLIs has negative impacts on the system transient response and operational stability, the fault isolation speed and energy dissipation of DCCBs. To solve these problems, an economical bridge-type multiport fault current limiter (BT-MFCL) is proposed in this article, which can be installed at the dc bus with multiple dc lines connected and can cooperate with the existing DCCBs. The BT-MFCL is composed of a CLI on each port and a shared energy dissipation circuit (EDC). The fault current can be limited by the embedded CLIs in the BT-MFCL without a time delay, while the EDC can eliminate the negative influences of CLIs. Extensive simulations and experiments have verified the effectiveness of the BT-MFCL. Besides, the performance comparison of the BT-MFCL with existing solutions is elaborated.