Low-Voltage Solid-State DC Breaker for Fault Protection Applications in Isolated DC Microgrid Cluster

Abstract

Due to the interconnected scheme of multiple components, such as distributed generators, storage systems, and loads through converters to a common bus in DC microgrids, the possibility of fault occurrence is increasing significantly. Meanwhile, due to the huge and rapid increase of short-circuit currents, the development of a small- and large-scale DC system requires a reliable and fast protection system to ensure fault clearance and maintain safety for the rest of the system. Thus, fault protection has been focused on as one of the most critical issues in a direct current network. The application of traditional circuit-breakers for DC fault protection has the drawback of slow operation, which requires a high rating power equipment. Recently, the high speed and excellent performance capabilities of semiconductor breakers have attracted a lot of attention and been considered as an optimal solution for fast DC fault interruption. In this study, a bidirectional Insulated-Gate Bipolar Transistor (IGBT) semiconductor breaker, suitable for the fault protection of low-voltage DC networks, is proposed. The operating characteristics of this breaker are based on changes in the circuit current and terminal voltage of IGBTs. It detects the abrupt change of the terminal voltage as an abnormal condition and isolates the faulted branch in a short time to prevent the operation disturbance in the healthy part of the network. Therefore, for the entire protection of a typical 400V DC-microgrid cluster, breakers need to be integrated and examined in each branch and the interconnected lines. The proposed protection method in this study is examined in a Simulink®/MATLAB environment to analyze and assess its operation.

Circuit Breakers in Low- and Medium-Voltage DC Microgrids for Protection against Short-Circuit Electrical Faults: Evolution and Future Challenges

“…SSCBs can be damaged due to overvoltage of the inductive components of the system, hence the importance of reducing this voltage for the safety of the device. To protect the solid-state switch from overvoltage at the moment of opening, additional elements are required, such as resistors, capacitors, diode (RCD) Snubber Circuits, metal oxide varistors (MOV), and freewheeling diodes [10,72]. In the Ref.…”

“…In the Ref. [10], a suitable IGBT for low-voltage (around 400 V) fault protection of a DCMG was proposed. The simulation results showed that the SSCB acted reliably and the fault current dropped to zero within 15 µs until the fault was removed from the system and reconnected within 8 µs, while the rest of the system continued to operate normally.…”

“…Si IGBT-based breakers have also been proposed to interrupt fault currents In the Ref. [10]. However, these breakers feature relatively high power losses due to the finite conductivity modulation effect of the IGBT [77].…”

“…However, implementation of DCMGs involves new technical challenges to reach their full potential; among them, the implementation of a suitable protection of the system [4,5]. Moreover, it has been highlighted that there are currently no standards or guidelines for DCMG implementation [6][7][8][9][10][11].…”

DC Fault Current Analyzing, Limiting, and Clearing in DC Microgrid Clusters

“…In Table 1, the focus of the reported studies on DC MG clusters is summarized to highlight the lack of enough investigations on the protection of these systems. In [22], an LV DC circuit breaker (CB) has been suggested for the protection of autonomous DC MG clusters. However, the interlink converter between individual DC MGs was not discussed in the paper.…”