Securing the grid

It isn’t any secret that the energy infrastructure responsible for generating, transmitting, and distributing electricity in almost every part of the country is aging and increasingly unstable.

The power grid has some century-old parts, long past their life expectancy. Significant power outages are becoming more frequent — the 2021 outages in Texas, for example, left millions of homes without power for days. These outages are worsened by climate change, which causes more of the natural disasters that have always been a threat to grid reliability.

An equally pressing issue with the grid is that it is not designed to accommodate the growing amount of renewable energy being generated. The grid was set up one-directionally, with electricity generated at large power plants, transmitted across high-power lines, then distributed to consumers.

But renewables require a two-way flow of electricity, such as from a rooftop solar array back to the grid. The grid also must be able to withstand the intermittent nature of some of these electricity sources, carefully balancing supply with demand, while storing excess energy in batteries for later use.

Fueling new technologies that could help with these large-scale concerns are UIC scientists who are researching ways to improve the electronic power system and contribute to a more reliable and resilient energy grid.

Integrating renewables to the grid

Nearly 20 percent of all electricity in the United States is generated through renewable sources. Even beyond their environmental friendliness, these sources — rooftop solar panels, wind generating units, and combined heat and power units, to name a few — have the ability to send energy back to the grid. Not only that, they could help to make the grid more efficient by cutting down on transmission losses, and could help keep homes and businesses powered when main power lines are shut down.

That’s the reason Lina He, an assistant professor of electrical and computer engineering, is focused on the modeling, control, protection, and security of power electronics-based power systems in the transmission and distribution levels of the grid. She is developing advanced control and protection techniques to better mitigate those impacts and to integrate wind and solar power plants to the power grid as well as to inverters, the devices that connect renewables to the grid by converting power from direct current (DC) to alternating current (AC) and maintaining needed voltage and frequency.

“That’s our job, to smooth the peaks,” He said. “Photovoltaics are dependent on sunshine. At night their output will be zero, and batteries are used to compensate. Inverter control integrates renewables to the system, and really impacts the resilience of the power system and reduces greenhouse gas emissions.”

Sudip K. Mazumder, a professor of electrical and computer engineering, also works on improving power inverters. “In designing inverters, there is more than just converting DC to AC. There are millions of ways of doing this, but what does the customer need? We want to make these inverters lighter, which will reduce labor, material, and transportation costs,” Mazumder said. “Or you may want to feed into a higher-voltage line. Then you need your inverter to operate at a higher voltage, which means more heat.”

Most silicone-based components cannot withstand high voltage and high temperatures, so wide bandgap materials, which generally fall between a traditional semiconductor and an insulator, are used instead. Their initial cost may be higher, but they compensate with better performance and are more efficient at extracting solar energy, feeding more to the grid.

Mazumder also works on increasing the grid’s reliability using artificial intelligence and machine learning. “There is a trove of data that can be employed to make inverters work more safely and intelligently, coordinating together to improve the grid,” Mazumder said.

Making batteries safer

To build a more secure grid, scientists also need to make the batteries that store renewable energy safer and more reliable. One of the main issues in battery safety is that electro-thermal aspects of lithium-ion batteries are far from being properly managed, as life-threatening accidents involving electric vehicle explosions have shown.

Vitaliy Yurkiv is focused on making battery technology long-lasting and safe for operation. He and Farzad Mashayek, both faculty in mechanical and industrial engineering, are trying to predict and prevent thermal runaway.

“Thermal runaway is one of the principal causes of lithium-ion battery failures occurring due to thermal or mechanical breakdown, internal or external short-circuiting, or electrochemical abuse,” Yurkiv said. “During battery operation, it is impossible to directly monitor the thermal runaway, but the change in thermo-electrical characteristics during thermal runaway-like events could signal the presence of a failure, allowing for the prediction of lithium-ion battery malfunction.”

With the help of machine-learning techniques, Yurkiv and Mashayek are able to use thermal images acquired from the multi-physics modeling of lithium-ion batteries to predict the likelihood of a thermal runaway. Reza Shahbazian-Yassar, a professor in mechanical and industrial engineering, is also working on making batteries more reliable and resilient. His team is focused on enhancing batteries’ materials and chemistry to ensure that they deliver increased energy density in a safe way.

The lithium-ion batteries used in current grid systems operate with flammable liquid electrolytes, which make them prone to catching on fire. Shahbazian-Yassar is conducting research to understand when overheating could occur in order to prevent it.

“We can change the chemistry of batteries to make sure we can prevent fire, and that innovation is based on solid state. The liquid is replaced with a solid material, which tends to not catch on fire suddenly and has the ability to resist high temperatures significantly,” he said.

In addition to researching the use of solid-state materials, Shahbazian-Yassar is using two-dimensional materials to control the performance of the batteries. He is adding a nano-coating layer to the separators within the battery to promote its safe operation. “It can improve the performance and safety liquid systems, and it is commercially attractive,” Shahbazian-Yassar said.

A balancing act

To add more renewables to the grid and accommodate their intermittent nature, coordination is key. In addition to robust battery systems to store energy, distributed energy resources must integrate with existing centralized systems to ensure that power supply to the grid stays in balance.

Mohammad B. Shadmand, an assistant professor of electrical and computer engineering, works on power electronics systems that coordinate between power controls and the grid. With an increasing number of distributed resources such as wind and solar being added to the power mix, information must be exchanged more frequently than with centralized systems to maintain equilibrium between supply and demand.

“We are designing control systems that have multi-layers and are exchanging information at multi-time-scales from every single device in a power grid to the utility center, and then back to those devices.” Shadmand said. “We can send a command to those devices to inject more or less power to support the power grid and ensure its resilient operation. The balance between demand and supply is the most important thing.”

This increased demand in information exchange requires more secure communications, as well as devices that can detect anomalous behavior. By detecting the attacks, the power electronic devices can prevent and heal some of the damage to the power grid, while consequently realizing an attack-resilient power grid.

“We need to make sure we have secure and resilient power electronics and a secure grid,” Shadmand said.