SELF - HEALING MICROGRID TECHNOLOGY

Abstract

Self-healing microgrid technology represents an innovative approach to enhancing the resilience, reliability, and efficiency of power distribution systems. By leveraging advanced sensors, real-time monitoring, artificial intelligence, and automation, self-healing microgrids are capable of detecting faults, isolating affected sections, and rerouting power autonomously. This technology minimizes the duration of outages and reduces the risk of widespread failures, particularly in critical infrastructure such as hospitals, military facilities, and emergency response systems. Self-healing microgrids also integrate renewable energy sources like solar and wind, coupled with energy storage systems, enabling continuous power supply even during disruptions to the main grid. Operating in both connected and island modes, these microgrids can function independently during grid failures, providing localized energy solutions in remote or disaster-prone regions. The implementation of smart algorithms and predictive analytics further enhances system reliability, ensuring optimal performance and reducing operational costs. This paper explores the key components, operational mechanisms, and real- world applications of self-healing microgrid technology, highlighting its potential to revolutionize energy distribution in a sustainable, decentralized, and resilient manner.

Specification

Description of the System:
> It may sound like a concept from science fiction, with tiny robots or some
sentient tech crawling around fixing power lines, but in a reality not far
from fiction, a team of researchers is bringing this idea to life.
> What's not hard to imagine is the potential value of a self-healing grid,
one able to adapt and bounce back to life, ensuring uninterrupted power
even when assailed by a hurricane or a group of bad guys. Together a
team from Sandia and New Mexico State University is making this vision
possible not with tiny robots, but rather a cutting-edge library of
algorithms.
> By coding these algorithms into grid relays, the system can quickly
restore power to as many hospitals, grocery stores and homes as possible
before grid operators can begin repairs or provide instructions.
> "The ultimate goal is to enable systems to self-heal and form these ad hoc
configurations when things go really bad," said Michael Ropp, Sandia
electrical engineer and the project lead. "After the system is damaged or
compromised, the system can automatically figure out how to get to a new steady state that provides power to as many customers as it possibly
can; that's what we mean by 'self-healing.' The key is that we're doing it entirely with local measurements, so there is no need for expensive fiber optics or human controllers."
> The electrical grid of the future, as envisioned by MichaeLand many
others, will have more renewable energy supplies such as rooftop solar
panels and wind turbines, along with local energy storage systems such as
banks of batteries. Many of these systems will have the ability to form
microgrids - small "islands" of power around hospitals, water treatment
plants and other critical infrastructure even if the main grid is down. This
Sandia project enables those microgrids to automatically heal themselves
when damaged and connect with one another to share power and serve as
many customers as possible.
> While microgrids can increase the resiliency of the grid, they need to
automatically perform certain critical functions like balancing energy
production with energy consumption and reconfiguring if part of the
system becomes damaged or unavailable. This self-healing capability
must also avoid connecting microgrids in a way that causes problems -
for example, by forming an unintentional loop in the circuit.


> Today, to achieve all of this in microgrids using power inverters, devices
that convert the direct current produced by renewable energy sources into
alternating current the grid can use, operators must install expensive high-
speed communications that can be unreliable during disasters and
vulnerable to cyberattacks. The purpose of this project, Michael said, is to support self-healing using only the measurements that each individual
device can make, reducing cost while.increasing reliability.
> One key function that microgrids with lots of inverters need to do is to
shut off a few customers when the demand for electricity becomes larger
than the supply. In grids powered by natural gas, coal or nuclear power
plants, when this demand-supply imbalance occurs, the frequency of the
grid drops.
> When the existing relay algorithms detect this, they disconnect power to
portions of the grid. However, inverters designed to power microgrids,
when they become overloaded, stop regulating the voltage of the power
supply, Michael said. The Sandia-led team developed an algorithm to use
this decrease in voltage to tell relays when to disconnect power to less
vital customers.
> During the wake of a natural disaster such as a hurricane or earthquake,
hospitals, assisted living facilities and water treatment plants are
especially vital and thus critical to keep powered. Banks, grocery stores,
and recreation centers or schools that serve as evacuation centers are also
quite important for the functioning of a community. Individual homes and
neighborhoods often aren't as vital.
> The team also developed algorithms that allow the system to self-
assemble in ways that avoid damaged areas. The team used computer-
aided-design software to model a small system of three interconnected
microgrids and showed how even without communications, their
algorithms allowed the system to balance power production and
consumption, isolate certain issues such as tree-downed lines or a
damaged power plant and work around the issue to restore power to
important facilities, Michael said. The researchers shared their results in a
paper published'as part of the 2022 North American Power Symposium.
> "A lot of good work has been done on how to protect circuits, equipment
and people from issues on the grid, which is why our electric grid is very
safe and reliable," said Olga Lavrova, an associate professor of electrical
engineering and former Sandia employee involved in the project.
"However, when we have a lot of renewables, solar and wind, we need to
make some changes to this logic, which is the focus of the project."
> Most of North America's grid infrastructure has single power lines with
one-way power flow to houses, offices and other average customers.
Thus, the grid is not designed to be stable when operated in a loop, said
Michael and Matthew Reno, another Sandia electrical engineer involved
in the project. Only certain custom-designed portions of the system can
operate as a loop.

> Microgrids and distributed resources like rooftop solar increase overall
resiliency but also allow the chance for the grid to assemble into an
unstable loop. Matthew said, "We were trying to come up with possible measurements to figure out if the two sides were already connected so
that closing the switch would form a loop."
> The team looked at some mathematical methods a breaker could use to
determine whether the portions of the grid on either side of the breaker
are powered by the same power supply and determined that two such
methods worked for this purpose. The researchers shared a comparison of
these methods in a paper published in the scientific journal IEEE
Transactions on Power Delivery.
> The team is also working on a solution to a similar problem: what to do
when a power line that normally is at the end of the system finds itself
supporting more current than it is rated for. They've developed a Morse-
code-like method where an overloaded line relay modulates the voltage
by opening and closing in a specific pattern, and the relays for lower-
priority customers can detect this pattern and disconnect themselves until
the line is no longer overloaded, Michael said.
> While this could be considered communication, it doesn't need a separate
system, which might be vulnerable to hackers, or a human operator - it
uses the power line itself to transmit the signal. The researchers plan to
share this method in a paper soon.

> The researchers have been working on ways to improve the performance
of these methods. For example, they have developed a method to quickly

divide the microgrid into smaller sub-microgrids when an issue is
detected.
> The hope is that this would isolate the issue to just one sub-microgrids,
allowing the others to operate normally. The team's initial testing
suggests that this method of defining microgrid boundary, points works
sometimes, but not all the time, so there is more work to do.
> Michael and the team would like to work with manufacturers of line and
load relays to incorporate their library of algorithms into the companies'
products, first to test them in a hardware-in-the-loop testbed and then
possibly in real life at test facilities such as Sandia's Distributed Energy
Technologies Laboratory or at a similar medium-voltage facility at New
Mexico State University, Lavrova said.
> "We definitely want this to become something that people can really use,
especially low-income communities that can't afford fiber optic
communications at every single point on every single electrical circuit,"
Michael said. "You can actually get very good performance and very
good resilience using our library of algorithms. And if you do have the
communications, this can be a backup."


CLAIMS
We Claim:
1. Self-healing microgrids utilize sensors and smart meters to continuously
monitor the health of the grid, detecting anomalies such as voltage
fluctuations, equipment failures, or line faults.
2. When a problem is detected, the system can automatically isolate the
affected section, preventing widespread outages and reducing the risk of
cascading failures.
3. After isolating the fault, the microgrid can quickly reroute power through
alternative pathways, restoring service to unaffected areas, often within
seconds.
4. Microgrids can operate independently from the main grid (island mode)
during dismptions, ensuring that essential services, such as hospitals,
remain powered even if the broader grid fails.
5. Self-healing microgrids often integrate renewable energy sources (e.g.,
solar, wind) and energy storage systems (e.g., batteries), allowing them to
remain operational during extended outages and reduce dependency on
fossil fuels.

6. By minimizing the duration and scope of outages, self-healing technology
reduces operational costs, repair time, and revenue losses associated with
downtime

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