Ameren Illinois, a regulated electricity-delivery company, was interested in building a microgrid with two nested microgrids at its Technology Applications Center near the University of Illinois to support the center and a 1-MW residential load. The project was intended to help the utility learn more about the operations, control, and integration of distributed energy resources on its distribution system.
Ameren wanted the microgrid to test 16 use cases where it saw a potential to create a return on investment, including improving grid resiliency and reliability; more easily incorporating renewable energy; and enabling the utility to go off-grid to supply power. Ameren also wanted the ability to "black start" the microgrid and be able to return to the grid from island mode without an outage occurring.
Ameren recognized the need for pursuing a microgrid where local distributed energy resources are becoming new generation sources. These resources include energy storage, natural gas, wind, and solar.
S&C Solution
The project involved creating a nested 50-kW microgrid within a 1-MW microgrid, all interconnected at 12 kV. S&C oversaw the construction of both a 100-kW wind turbine and a 125-kW solar array for Ameren and provided the utility with two 500-kW natural gas generators as additional alternative energy sources. Most importantly, S&C included a 250-kW/ 500-kWh energy-storage system that would serve as the backbone of the 50-kW microgrid, enabling it to operate on 100% renewable generation.
Working with Ameren, S&C developed adaptive protection and control software to help transition the multiple generation sources into and out of "microgrid mode" without creating an outage. Separately, following a utility outage, S&C developed a means to "black start" the microgrid without the need for a reference voltage from the utility source. This was accomplished by deploying a battery energy storage system for the smaller microgrid to fully integrate renewable energy sources, such as wind and solar.
S&C supplied Remote Supervisory Vista® Underground Distribution Switchgear to integrate the various systems. It also provided SpeedNet Radios to support device communication. To provide the "glue" to make the various sources of generation work smoothly both on the main grid and within the islanded microgrid, S&C deployed the GridMaster® Microgrid Control System.
Results
With a microgrid operating at a utility-scale voltage of 12 kV with multiple levels of control Ameren is now well on its way to researching microgrids and how to use them to supply power at the distribution level for future endeavors. This also was a "first-of-its-kind" engineering effort; no company had previously developed a way to conduct a seamless return to utility power after entering microgrid mode at utility-scale voltages.
The Ameren microgrid became the first utility-scale microgrid to earn a Gold PEER (Performance Excellence in Electricity Renewal) certification. The certification recognizes systems that implement industry best practices and encourages the adoption of innovation strategies that improve efficiency, day-to-day reliability, and overall resiliency.
