DC Solid-State Circuit Breakers with Two-Winding Coupled Inductor for DC Microgrid

Abstract

Ensuring a protection scheme in a DC distribution system is more difficult to achieve against pole-to-ground faults than in AC distribution system because of the absence of zero crossing points and low line impedance. To complement the major obstacle of limiting the fault current, several compositions have been proposed related to mechanical switching and solid-state switching. Among them, solid-state circuit breakers (SSCBs) are considered to be a possible solution to limit fast fault current. However, they may cause problems in circuit complexity, reliability, and cost-related troubles because of the use of multiple power semiconductor devices and additional circuit configuration to commutate the current. This paper proposes a SSCB with a coupled inductor (SSCB-CI) that has a symmetrical configuration. The circuit is comprised of passive components like commutation capacitors, a CI, and damping resistors. Thus, the proposed SSCB-CI offers the advantages of a simple circuit configuration and fewer utilized power semiconductor devices than the other typical SSCBs in the DC microgrid. For the analysis, six operation states are described for the voltage across the main switches and fault current. The effectiveness of the SSCB-CI against the short-circuit fault is proved via simulation and experimental results in a lab-scale prototype.

State of the Art of Low and Medium Voltage Direct Current (DC) Microgrids

“…Safety and reliability issues include switches and protection schemes, which are not as developed as their AC counterparts. Means to anticipate and overcome possible faults (fault detection and avoidance techniques) in the DC MG need to be thoroughly investigated before the large-scale deployment of such architectures [115][116][117].…”

Feedback Linearization-Based Control Strategy for Interlinking Inverters of Hybrid AC/DC Microgrids with Seamless Operation Mode Transition

“…Generally, in order to comply with a high requirement of consumers and a highly reliable power system for the higher quality of the supplied power distribution, the microgrid is essentially required to be able to operate under off-grid and on-grid modes. Physically connecting or disconnecting the microgrid to the AC network is usually carried out through a semiconductor device-based static transfer switch (STS), which is simply controlled [10]. In terms of control and operation, the interlinking inverter of the microgrid is required to obtain fast, stable, and seamless transition modes between on-grid and off-grid operations, which deliver the powers to the grid under normal grid conditions and protect the microgrid and loads under the grid fault conditions [11][12][13].…”