Ameren Corporation, a Midwest-based utility, and S&C Electric Company, a smart grid leader shaping the future of power delivery, conducted a successful 24-hour islanding test in August at the recently deployed Ameren microgrid in Champaign, Illinois. The microgrid — one of the most technologically advanced utility-scale microgrids in North America — has been operational since May and has now proven it can provide a seamless transition from grid-connected to island mode.

The test focused specifically on the 50kW microgrid at the site, which powers an Ameren research facility. The complete microgrid includes 225kW of renewable generation (PV solar and wind) and 250kW / 500kWh of battery energy storage.

The test began at 8 a.m. on Aug. 3, 2017, with the battery's state of charge at 97 percent capacity. Once the battery was depleted to 90 percent capacity, solar and wind generation kicked in, simultaneously carrying the load and charging the battery. This pattern continued throughout the day, never letting the battery fall lower than 88 percent capacity. In short, the microgrid functioned without any human interaction, automatically coordinating resources and ensuring power never faltered.

Upon conclusion of the 24-hour test, the microgrid successfully moved back into grid-connected mode without any loss of power for end users.

"We have one of the few microgrids in the world that operates at utility-scale voltages and can seamlessly transition from grid-connected to islanded mode," said Ron Pate, senior vice president, operations and technical services at Ameren Illinois. "This successful test provided tangible proof that the system can accomplish what it was designed to do. The microgrid isn't theoretical and our tests don't need to be lab simulations. We were able to prove that this technology works and can provide key benefits to our customers."

IEF