Technical Requirement for Load current switches in MVDC system and Verification

At present, in medium-voltage direct current (MVDC) system, the load current switching operation is mainly accomplished by using DC circuit breaker (DCCB) as load current switch (LCS). However, if the transient switching process of the load current is considered, the transient voltage established by the DCCB is much higher than the actual required transient voltage, which greatly increases the cost. To address this issue, this paper analyzes the technical requirement for load current switches in MVDC system and verifies it by proposing a new LCS. Through an analysis of different voltage requirements between HCB and LCS switching currents, the system requirement of LCS is revealed. Subsequently, a new LCS based on power electronic devices is proposed, and detailed descriptions of its topology, working principle, and operation flow are provided. In the end, the technical requirement for load current switches in MVDC system is verified based on theoretical analysis and simulation results, and performance advantages of proposed load current switch are demonstrated.