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Nowadays, traditional DC circuit breakers (DCCBs) are always expensive and lack current-limiting capabilities. Hence, this paper proposes a current limiting and low-cost hybrid DC circuit breaker (HCB). When a fault occurs, the paralleled inductors in the proposed HCB are converted to a series connection due to the cutoff of the converter module, effectively limiting the increase of fault current. Then the cascaded IGBTs undertake the transient interruption voltage. Energy dissipation circuits (EDCs) reduce the fault isolation time (FIT) by bypassing the current-limiting inductor during energy dissipation based on the metal oxide varistors (MOVs). Therefore, the proposed HCB can limit the rate of the fault current increase, reducing the FIT and cost. Finally, the feasibility of the proposed HCB is verified by a single-ended equivalent system and DC grid test systems built in PSCAD/EMTDC. In addition, the proposed HCB FIT is 33.7% quicker, its energy consumption is 87%, and its cost is lower than that of the traditional ABB HCB. [ABSTRACT FROM AUTHOR]

Power flow controllers and DC circuit breakers are compulsory components in a multi‐terminal DC grid with overhead lines. They are both composed of similar power electronic devices and thus can be reasonably combined together to realize cost savings. This paper proposes a multi‐port circuit breaker integrated with a multi‐port power flow controller (M‐PFCHCB). The topology structure, operation principles, control strategy and parameter configuration are illustrated in detail. The main breakers are composed of unidirectional power electronic switches, and the selection branch is based on two diode strings, which can significantly save the investment of the breaker. The proposed M‐PFCHCB is able to deal with the fault isolation and the ultra‐fast disconnector failure with high performance. Besides, the power flow of multiple lines can be simultaneously regulated by the M‐PFCHCB without any external power supply. The internal power balance is achieved by controlling the AC circulating current inside the M‐PFCHCB. The simulations conducted on PSCAD in a five‐terminal DC grid with eight DC lines verify the feasibility of the proposed M‐PFCHCB. The technical and economic analysis performed proves that the proposed M‐PFCHCB can achieve the comprehensive functions of fault isolation and power flow control with low construction cost. [ABSTRACT FROM AUTHOR]

Two key challenges in meshed multi-terminal dc (MTdc) grids are line power flow management and fault current interruption, which can be solved by current flow controllers (CFCs) and hybrid dc circuit breakers (HCBs), respectively. However, the power losses and the implementation costs of CFCs and HCBs are relatively high. In order to overcome these drawbacks, a combined HCB (CHCB) is proposed in this article by fully utilizing the core ideas of the interline dual H-bridge CFC and the HCB. The proposed device can substitute multiple HCBs at a dc bus with greatly reduced cost. In addition to the fault current interruption capability, the current flows in the adjacent lines can be controlled by the embedded multi-line CFC in the CHCB expanded from the existing interline dual H-bridge CFC. The system-level behavior of the proposed CHCB is similar to the separate solution of the typical HCB and the multi-line CFC. Extensive simulations and experiments verify the effectiveness of the proposed device. Besides, a comparison of the proposed CHCB and the separate solution is presented. [ABSTRACT FROM AUTHOR]