| Project Detail |
Today’s power grid relies primarily on alternating-current (AC) electricity as opposed to direct-current (DC). DC has advantages over AC such as lower distribution losses, higher power carrying capacity, and reduced conductor materials, which make it well suited to industrial applications, transportation, and energy production. However, the risk associated with electrical faults, such as short circuits, and system overloads, continues to hinder the growth of DC markets. Inherently, AC electricity periodically alternates direction, providing a brief “zero crossing,” where no current flows. This characteristic allows electrical faults to be interrupted by conventional electro-mechanical breakers. DC networks deliver power without zero crossings, which make conventional circuit breakers ineffectual in fault scenarios. To fully benefit from medium voltage (MV) DC usage, fast, highly reliable, scalable breakers must be developed for commercial deployment.
Project Innovation + Advantages:
Sandia National Laboratories will develop a solid-state circuit breaker for medium to high voltage applications based on a gallium nitride (GaN) optically triggered, photoconductive semiconductor switch (PCSS). During normal operation, the current will flow through high-performance commercial silicon carbide (SiC) devices to achieve high efficiency. When a fault occurs, the fast-response GaN PCSS will be used to break the current. The concept builds on Sandia’s knowledge of optically triggered GaN devices, as well as the team’s experience in circuit design for MV applications. The GaN PCSS will enable high-voltage operation, potentially scalable from 1 to 100 kV, while achieving superior electrical isolation due to the optical triggering approach. This technology could contribute to more widespread adoption of MVDC power distribution across the grid.
Potential Impact:
The proposed breaker is installed close to loads to rapidly detect and react to the short-circuit fault. Thus, it could enable an increased number of electronic loads that operate using DC, such as ultra-fast electric vehicle charging stations and utility scale energy storage battery units, to connect to the MV distribution grid. This would improve overall power delivery efficiency. |
