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Duke Energy is getting charged up about batteries


By Dan Sowder, Senior Project Manager, Duke Energy


Batteries are nothing new. They’ve been around for more than 100 years.

But over the past few years, utility-scale battery technology has been making great strides and will likely have useful applications for the utility industry.

Duke Energy is actively testing several different applications and battery systems to determine how energy storage can make the grid stronger and more efficient.  One of our battery installations, at the Rankin Substation in Mount Holly, N.C., gives a glimpse into how energy storage may ensure grid reliability in a future with more distributed, intermittent generation.

At the Rankin substation, a 402-kilowatt/282-kilowatt-hour sodium nickel chloride battery system is smoothing out large minute-by-minute peaks and valleys in electricity production from a 1.2-megawatt solar facility at an industrial complex about three miles away.

The system is connected to a 12.47-kV distribution circuit and is designed to detect and respond to solar-induced intermittency from any source connected to the circuit. This could include hundreds of residential rooftop solar installations dispersed across a distribution circuit.

As clouds roll by, solar output can rapidly transition from 100 percent to practically zero. In a future with more commercial and residential rooftop solar, utilities will need methods to smooth fluctuations caused by these intermittent generators. 

At Rankin, a closed-system algorithm enables the system to measure, calculate and respond to changing circuit parameters every 500 milliseconds.  

Duke Energy partnered with Italy-based FIAMM Energy Storage Solutions, which provided the batteries, and Chicago-based S&C Electric Company, which provided the power electronics.

But just as important, the project demonstrated how Duke Energy’s traditional competency in designing and operating a reliable grid can be applied to new technologies such as energy storage.

Duke Energy’s distribution team played a critical role in ensuring this system strengthened the grid and was effectively tested within the fence of an important retail substation.

Performance data collected from the Rankin system is giving Duke Energy insight on how to optimally design, install and increase the value from energy storage connected to the grid. This experience is also helping Duke Energy envision how new technology can make the grid smarter.

Projects like Rankin will enable energy storage to become an important tool in helping utilities absorb the increased penetration of intermittent renewable generation on the grid. 

Dan Sowder is senior project manager with Duke Energy.



Kathleen Wolf Davis's picture

Thank Kathleen for the Post!

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