This research proposes a solid-state dc circuit breaker for low voltage dc system based on reverse-blocking integrated gate-commutated thyristor (IGCT). The circuit breaker topology gets easier as a result of reverse-blocking IGCTs’ ability to withstand reverse voltage. To further enhance the breaking process, we develop a snubber branch with metal oxide varistors (MOVs) and capacitance. The advantages and disadvantages of three distinct snubber branches—the no-snubber, the resistance–capacitance ( RC ), and the MOV-C snubber branch—are then contrasted. In addition to suppressing high-frequency oscillation caught by the parasitic MOV parameters, the structure with MOV-C snubber branch also blocks low-frequency harmonics brought on by RC snubber branch. Moreover, this structure can slow down the rate at which the voltage rises during the breaking process. Comparatively speaking to the RC snubber branch and no-snubber branch structures, it is more appropriate for solid-state dc circuit breakers. Finally, a solid-state dc circuit breaker prototype based on RB-IGCT and MOV-C branch has been created. The maximum overvoltage is 1.5 kV and the rated voltage is 750 V. The maximum breaking current is 10 kA and the rated current can be 2 kA.

Hybrid DC circuit breakers (HDCCBs) are promising solutions to DC breaking issues. However, HDCCBs based on forced commutation have the disadvantages of high conduction loss and high cost. Natural commutation HDCCBs have low loss and cost but face the contradictions of high arc voltage and fast post-arc recovery. This paper proposes a natural commutation-type hybrid DC circuit breaker based on a series vacuum and gas gap. The high arc voltage characteristic of the gas gap is used to drive natural commutation, and the fast dielectric recovery characteristic of the vacuum gap is used to withstand transient overvoltage. It has the advantages of low cost and compact volume. The characteristics of the arc voltage of the gas mechanical switch are analyzed, and the influence of different factors, such as the opening speed, arc current, gas type, magnetic field and gas pressure, on the arc voltage of the gas mechanical switch is studied. Moreover, a design method for the gas mechanical switch is proposed. On this basis, a prototype of a 10 kV natural commutation-type DCCB based on hybrid gaps is developed and tested, and the breaking current can reach 15 kA, which verifies the feasibility of the natural commutation method.

Hybrid DC circuit breakers (HDCCBs) have excellent performance in terms of breaking speed and low losses and have become the mainstream technology for dc fault isolation in dc grids. However, because of the breaking limitation of the solid-state branch in HdcCBs, the existing HdcCBs are still weak in breaking high current. Although the breaking ability can be improved by series and parallel devices, the cost will increase rapidly, and it is very difficult to share current by paralleling a single type of device. This article proposes a novel HdcCB topology that combines two types of power electronic devices in solid-state branches to meet the requirement of a large breaking capacity in dc grids. The structure and breaking principles of this novel topology, which aims to break high current, are introduced. The design methods of the key parameters are presented. Then, the current breaking ability of the novel topology is verified by developing a prototype completing a 10 kV/60 kA breaking test in 3 ms. Finally, this novel topology is compared with other dc circuit breakers at the same breaking level, which shows that this novel topology has obvious advantages in cost and volume with fewer devices.

Medium voltage dc system has fast rise rate in the event of a short-circuit fault. To avoid high-peak fault current, it is necessary to configure dc circuit breaker with fast operation. Solid-state dc circuit breaker has short breaking time and high reliability, which is suitable for Dc system. In this letter, a novel oscillating-commutation solid-state dc circuit breaker based on compound integrated gate-commutated thyristors (IGCTs) is proposed. By combining IGCTs with different advantages, such as high current breaking and high withstand-voltage capability, the proposed dc breaker has the advantages at less breaking time, high performance, low cost, and small volume. The working principle of the proposed scheme is described in detail, and an 8 kV prototype with 7 kA current breaking ability is built to verify its feasibility.

An arc is the high‐temperature discharge plasma produced in the opening process of mechanical switches, which directly affects the breaking capability of a hybrid DC circuit breaker. According to the physical mechanism of an electric arc, the construction of an arc model for simulation analysis is an important technical means in the electrical field. In this study, based on the theory of magneto hydrodynamics (MHD), a gas mechanical switch model of a natural commutation DC circuit breaker with a compound gap is established. The arc motion process under different conditions is simulated and calculated. The influence of different initial pressures, different opening speeds, and different striking currents on the arc voltage characteristics is analysed. The results show that the larger the gas pressure, the smaller the arc volume and the higher the arc voltage. The faster the opening speed, the longer the arc and the higher the arc voltage; with the increase of the current, the arc voltage increases rapidly at a low current, while the arc voltage increases slowly at a high current.

Flexible dc grids have become an important means to support large-scale new energy integration utilization due to their advantages of flexible power control and high efficiency. Flexible dc grids generally consist of multiple converter stations and dc lines. Therefore, there are multiple line intersection points, and dc circuit breakers (DCCBs) need to be installed at the intersection to isolate faults. Multiport hybrid DCCBs (MPHCBs) based on topology optimization can greatly reduce the cost by replacing multiple two-port DCCBs with one multiport DCCB at the intersection. However, currently researched multiport DCCBs still have a high cost and large volume while lacking engineering verification. This letter proposes a hybrid multiport DCCB based on a bridge commutation branch that greatly reduces the number of power electronic devices used and the cost and volume of the DCCB. First, the topology and control method of the proposed MPHCB are studied, and its cost and reliability are analyzed. Then, the breaking test of the proposed MPHCB based on the bridge commutation branch is carried out at a 15 kV voltage level. The results show that the proposed MPHCB can interrupt a 15 kA current in 3 ms, which verifies the feasibility of the scheme.