Hybrid circuit breakers are a class of protection devices to facilitate fault current limitation and fast interruption in AC and DC power systems. They are one of the key enabling technologies of multi-terminal DC transmission and distribution systems. As the power rating of DC power systems increases, mechanical switches in the normal conduction path are chosen to provide low on-state loss in a hybrid circuit breaker topology. These mechanical switches require fast actuation to achieve sub- millisecond switching capability, for which only a few actuation mechanisms have been reported to be suitable. Besides electromagnetic repulsion methods like the Thomson coil, piezoelectric actuators also appear to be a good candidate. This paper provides a survey on potential mechanical switches for hybrid circuit breakers considering different actuation mechanisms. Performances of mechanical switches reported in the literature have been summarized and compared, such as response time, displacement, and required actuation energy.
more »
« less
Short Circuit Fault Discrimination Using SiC JFET Based Self-Powered Solid State Circuit Breakers in a Residential DC Community Microgrid
This article identifies and validates the use of ultrafast silicon carbide (SiC) junction field effect transistor (JFET)-based self-powered solid-state circuit breakers (SSCBs) as the enabling protective device for a 340 Vdc residential dc community microgrid. These SSCBs will be incorporated into a radial distribution system in order to enhance fault discrimination through autonomous operation. Because of the nature and characteristics of short-circuit fault inception in dc microgrids, the time-current trip characteristics of protective devices must be several orders of magnitude faster than conventional circuit breakers. The proposed SSCBs detect short-circuit faults by sensing the sudden voltage rise between its two power terminals and draw power from the fault condition itself to turn off SiC JFETs and then, coordinate with no-load contacts that can isolate the fault. Depending upon the location of the SSCBs in the microgrid, either unidirectional or bidirectional implementations are incorporated. Cascaded SSCBs are tuned using a simple resistor change to enable fault discrimination between upstream high-current feeds and downstream lower current branches. Operation of one of the SSCBs and three in cascaded arrangements are validated both in simulation and with a hardware test platform. Thermal impact on the SSCB is discussed as well. The target application is a residential dc microgrid that will be installed as part of a revitalization effort of an inner city Milwaukee neighborhood.
more »
« less
- Award ID(s):
- 1650470
- NSF-PAR ID:
- 10316419
- Date Published:
- Journal Name:
- IEEE Transactions on Industry Applications
- ISSN:
- 0093-9994
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
null (Ed.)Due to dc microgrid nature, dc fault current has no zero-crossing current and could increase up to a thousand amps. Because of that, a dc circuit breaker (DCCB) with the ultra-fast response and high efficiency is required. Regarding this issue, this paper presents a novel thyristor-based DCCB. Then the optimal values of the proposed DCCB components are obtained by cost-power loss multi-objective optimization method. Finally, to keep the maximum temperature of the thyristor below the maximum allowed value, an optimum forced-air microchannel that has high reliability, low cost, and high efficiency is proposed for the proposed thyristor-based DCCB.more » « less
-
null (Ed.)This paper presents the fault-tolerant operation for a cascaded H-bridge (CHB) inverter. The added features ensure reliable and robust operation in the event of a fault. The proposed strategy uses an additional cross-coupled CHB (X-CHB) unit in companion with the existing CHB to support the output voltage and ensure continuity of operation in case of an open/short circuit fault. The operation of the proposed X-CHB inverter is described in detail. Simulation and experimental verification of the proposed concept is demonstrated using a seven-level CHB. Both simulation and experimental results validate the fault-tolerant operation of the CHB for a battery energy storage system (BESS) in case of switch faults such as open/short-circuit switch faults or dc-source or battery failure.more » « less
-
DC microgrids have attracted significant attention over the last decade in both academia and industry. DC microgrids have demonstrated superiority over AC microgrids with respect to reliability, efficiency, control simplicity, integration of renewable energy sources, and connection of dc loads. Despite these numerous advantages, designing and implementing an appropriate protection system for dc microgrids remains a significant challenge. The challenge stems from the rapid rise of dc fault current which must be extinguished in the absence of naturally occurring zero crossings, potentially leading to sustained arcs. In this paper, the challenges of DC microgrid protection are investigated from various aspects including, dc fault current characteristics, ground systems, fault detection methods, protective devices, and fault location methods. In each part, a comprehensive review has been carried out. Finally, future trends in the protection of DC microgrids are briefly discussed.more » « less
-
Proliferation of power electronics and distributed energy resources (DERs) into the electrical power system (EPS) enables improvements to the network’s resilience against sudden-inception short circuit electrical faults through redundant electrical pathways in meshed configurations and multiple possible distributed generation locations. However, successful operation of fault detection, isolation, and recovery in islanded mode is challenging as protection coordination must include not only the distribution equipment, but also the DERs. Assessment of resilience for candidate EPS architectures against short circuit faults must be performed to understand the trade-offs between network resilience and complexity. This paper proposes a design process, which can be used towards assessing microgrid resilience, by coordinating protection and ride-through settings to maximize the recoverability of a meshed islanded AC microgrid. The design process is demonstrated through a case-study.more » « less
- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1109/TIA.2020.2995114
