Sandia National Laboratories design grid-resiliency algorithm


A group of researchers at Sandia National Laboratories are studying ways to increase grid resilience to extreme weather storms and hackers. Their idea is to build a self-healing grid through various algorithms coded into grid relays. These detectors would quickly restore power for critical infrastructure, including hospitals, grocery stores, assisted living facilities, and water treatment plants, before operators can implement repairs or provide direction on moving forward. 

Researchers at Sandia imagine these grid relays embedded in microgrids of renewable energy supplies and their local energy storage systems. The Sandia project is focused on ensuring these small islands of power around critical infrastructure can automatically heal themselves and connect to share electricity, powering as many users as possible. 

Sandia researchers plan to build this resilience by ensuring microgrids can automate functions like balancing energy production with consumption and reconfiguring if part of the system is impaired. The algorithm must also prevent microgrids from forming an unintentional loop in the circuit. All while leveraging device-specific local measurements to avoid the costs of having to depend on power inverters that currently offer the high-speed communications necessary. 

Sandia National Laboratories electrical engineer Michael Ropp, who is part of the research team exploring grid resiliency.

Image: Sandia National Lab

When it comes to automating energy production and consumption regulation, the Sandia-led team developed an algorithm based on the process inverters designed to power microgrids use when overloaded. However, instead of stopping to regulate the voltage of the power supply during surcharge, the new system uses the decrease in voltage to signal relays to disconnect power to less vital customers like those in individual homes. 

Regarding reconfiguration, the automated process is based on computer-aided design software. The proposed algorithms of three small interconnected microgrids were able to isolate issues, including tree-downed lines or a damaged power plant, and then restore electricity to essential infrastructure. 

Researchers state that the current grid is not designed to be stable when operated in a loop, as much of North America’s original infrastructure is compatible with single power lines with a one-way power flow to customers. As the development of microgrids and rooftop solar increases, so does the opportunity for the grid to assemble into an unstable loop. For now, researchers are exploring how local measurements can clarify which sides of a line are already connected, thus forming a loop if the switch were closed.  

Researchers have developed a morse-code-like method to troubleshoot unintentional loops. It allows an overloaded line relay to modulate voltage by opening and closing in a particular pattern. The tool also provides relays for lower-priority customers to detect the pattern and disconnect themselves from the line until it isn’t overloaded. Researchers state the method doesn’t need a separate communication system, which adds a level of protection against cyberattacks as it uses the actual power line to transmit a signal. 

As researchers streamline each method’s performance, they hope to collaborate with line and load relay manufacturers to test how the algorithms fare when integrated into their products. Preliminary demos would occur in a hardware-in-the-loop testbed, then at test facilities like Sandia’s Distributed Energy Technologies Laboratory.  

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