Customer Support

May 2018

Battery Micro-grid Collaboration Leads to New Insights

An energy storage project in Denver is focused on understanding how battery storage can help work with renewable energy on distribution feeders, as well as use batteries in other ways to support the grid.

Online since December, the battery system is located near Panasonic’s headquarters in Denver, at the Pena Station rail line stop near Denver International Airport. The project is located on the company’s distribution system and can provide backup power to Panasonic in the case of an outage – serving in a capacity known as a microgrid. Most of the time, however, the battery is not needed for backup power and provides support to a local distribution feeder.

Through a public/private partnership between Xcel Energy, Panasonic and Denver International Airport, s team worked to develop the concept for the Panasonic Battery Demonstration Project, said Beth Chacon, director of Emerging Technologies.

“This effort aligns with the company’s ongoing efforts to understand battery technologies,” she said. “The cost of battery storage is falling, and both our customers and the utility industry are deploying these systems more widely.

“It’s important that we understand how batteries can support our system,” she added. “Demonstration projects like this help us understand procurement, engineering, design and integration requirements. We want to build our expertise early, as we expect adoption of this technology to increase.”

The Pena project consists of four primary components – a 1.3-megawatt carport solar installation; a 240-kilowatt rooftop photovoltaic (PV) system at Panasonic’s facility; a lithium-ion battery system; and the switching and control systems required to operate the energy-storage system and microgrid.

The project is located on a new 400-acre development called Pena Station NEXT, which is located southwest of the airport. Its campus is part of a collaboration aimed at building a community with renewable energy, sustainable construction, shops and restaurants, and intermingled with community centers, playgrounds, bike paths and public transportation.

Over the course of the two-year demonstration, the system will be tested under multiple scenarios to determine how it can be used to increase reliability and resiliency for both Xcel Energy’s electric grid and the Panasonic facility. Testing started in January, and initial results are expected later this year, from the project, which is located on a company feeder that has 30 percent solar penetration, she said.

“A primary objective of the project is to demonstrate how battery storage can help integrate renewable energy into the electric grid,” Chacon said. “It does this through ‘solar smoothing’ and ‘solar time shifting.’

In a smoothing mode, the battery will charge and discharge to minimize rapid fluctuations in PV output. In a time-shifting mode, the battery will store excess solar generation when output is high, such as midday, and dispatch energy later in the day, she said.

This approach helps reduce system feeder peak. The battery will also be tested in an energy-arbitrage scenario, storing power when energy prices are high and discharging energy when prices are low.  Using batteries for different functions helps increase their utilization, she said, which may lead to more cost-effective applications.

In time, providing backup service through a microgrid may be more cost effective than traditional solutions, such as providing customers with access to an alternate feeder through automatic throw-over switches. This solution could prove to be ideal for customers in remote locations or where alternatives are otherwise cost prohibitive, Chacon said.

In the event of an outage, the battery storage system will automatically form a microgrid, allowing the battery to provide power to the Panasonic building. In this mode, both the battery and rooftop PV will provide power to Panasonic. Should power from the PV system exceed the building’s needs, excess energy will be stored in the battery.

“It is quite an accomplishment to put together an innovative project so quickly,” Chacon said. “For us, working with large companies like Panasonic and Denver International Airport is nothing new, but these type of efforts usually take time to build consensus, and working together was the only way we could successfully deliver this project.

“There had to be compromise on all sides to ensure everyone’s core needs were met,” said Andre Gouin, a consultant with the Business Technology group in Customer Solutions. “Being located at Panasonic’s new headquarters created plenty of pressure, and a lot of motivation to get the project done right.”

The project provided a number of learning opportunities for Xcel Energy, including a framework for future battery-storage projects and how they would be integrated onto the company’s system, he said.

“This was the first battery project that we integrated on our distribution system,” Chacon said. “One way we overcame challenges involved developing ‘use cases’ with help from the Electric Power Research Institute.

“The process forced us to walk through scenarios around how the battery would operate,” she added. “Each team member had slightly different perceptions on how the battery system would operate, and these discussions allowed us to come to agreement on how this emerging technology might work.”

The project has faced other interesting challenges, as well.

“With Colorado winters, we actually have to heat the battery compartments,” Gouin said. “And with the wind on the plains, we had to install additional weather stripping to stop dust from blowing into the battery containers.”

Other parts of the company were helpful in the project, as well, and included Business Systems, the Distribution Control Center, Energy Supply, the Trouble organization in Transmission and a special maintenance group in Distribution.

“Throughout this effort, we found that all members of the team were committed to making the project successful,” Chacon said. “They enjoyed learning about the new technology even though it took extra effort. This is a great example of how we are delivering innovative solutions to our customers by exploring battery technology.”



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