The system, which has been developed at Oncor's System Operating Services Facility (SOSF) near Lancaster, Texas, comprises four interconnected microgrids utilizing nine different distributed generation sources. These include two solar photovoltaic arrays, a microturbine, two energy storage units and four generators. To turn these diverse generation assets into a microgrid, S&C and Schneider Electric developed a distribution automation scheme that leverages multiple intelligent grid solutions from both companies – enabling the four microgrids to effectively operate independently or as one larger microgrid.
The system also includes a facility to showcase the microgrid’s technologies and its benefits.
Distribution automation system
During a loss-of-power event, a combination of S&C's advanced distribution automation equipment and Schneider Electric's microgrid controller use high-speed communications and distributed grid intelligence to automatically detect a problem on the grid within a matter of seconds. S&C's IntelliRupter PulseCloser fault interrupter detects an interruption in power, tests to see if the issue is temporary or permanent, and if it is permanent dynamically islands the facility. The system then uses S&C's Scada-Mate CX switches and Vista underground distribution switchgear to automatically re-configure the distribution system while the microgrid controller autonomously switches to alternative distributed power sources.
The energy storage systems are the backbone of the microgrid, and include S&C's PureWave community energy storage system. The onsite energy storage – which stores energy from either the utility feed or any of the facility's generation sources – provides the voltage signal for the site, enables renewable integration, controls the microgrid frequency and is the first generating source to respond during an unexpected loss of power.
Advanced grid technologies from Schneider Electric, in addition to the controller, include the PowerLogic load preservation system and the new StruxureWare Demand Side Operations (DSO) technology. Schneider Electric's DSO model delivers economic optimization and dispatch of the microgrid distributed energy resources (DER), allowing the system to maximize renewable energy usage and storage while minimizing energy costs. DSO's platform makes this possible by leveraging market pricing signals, weather and forecasting information, historical energy usage data and real-time building information.
Microgrid demonstration facility
To help educate and demonstrate the benefits of microgrids to residents, students, policymakers and businesses, S&C and Schneider Electric were asked to develop a microgrid demonstration facility on the SOSF campus. That facility, to be known as Oncor's Technology Demonstration and Education Center (TDEC), also serves as the SOSF microgrid control center.
“Oncor has a rich history of working collaboratively with its vendor partners and this is a great opportunity to showcase those relationships in a state-of-the-art microgrid facility,” says Michael Quinn, Oncor chief technology officer.
The Center consists of two exhibits – an immersion room and a demonstration center. In the immersion room, the Oncor microgrid story is brought to life on seven screens for a full cinematic experience. The demonstration room features a fully functioning SCADA representation of the microgrid to show how the system reacts to a loss of power event such as extreme weather. Once an event is created, the switching devices respond accordingly, clearing the fault, isolating the faulted section and restoring service from an alternate source. The switching devices, controls, communications and software shown are all real and completely functional.