The campus microgrid system will include three different types of distributed energy resources (DERs), including solar energy generation, energy storage systems and load management devices. All the components of the system will be operated by a single PXiSE microgrid controller, a highly advanced controller which communicates with the generation and storage equipment and provides frequency and voltage support locally and to the utility distribution grid. Together, all elements will create a flexible microgrid system that can transition seamlessly between islanded operation and grid interconnected operation, providing reliability to the community in an emergency. During regular, “blue-sky” operations, the microgrid will help the campus optimize its energy use and reduce peak demand on the grid and will provide an additional economic value stream to the university by participation in a utility demand response program.
To help establish a baseline profile for campus energy use, 18 new Accuenergy Acuvim IIR series meters and 3 new Accuenergy Acuvim IIR with Aculink 810 Data Servers were installed at a combination of campus buildings and existing DER equipment. These new submeters measure building level energy consumption, solar PV production, and BESS charge and discharge. The meters will be integrated into the campus’s central energy management system (EMS), along with the existing Acuvim II meters that were already installed on campus, to provide data necessary to monitor the performance of the microgrid system once installed.
All components of the microgrid will be controlled by a single, high-speed microgrid controller, designed, integrated and managed by PXiSE Energy Solutions LLC. The PXiSE controller is a software-based solution housed inside of a common industrial computer and provides advanced frequency and voltage support benefits not currently supported by other microgrid software. Load profiles developed for the microgrid system will be used to configure the microgrid controller so it is able to optimize energy use and maximize utilization of the solar generation and energy storage systems.
The college has four existing solar PV systems onsite, including one rooftop system installed on the Doyle Library in 2007 and three systems mounted on car port structures installed in 2018 and 2019. The existing PV systems are estimated to produce a total of 3,693,399 kWh-AC per year. When integrated into the microgrid system, the solar generation is expected to reduce the demand on the utility grid by an average of 40% each year.
Additionally, SRJC has future plans to install an additional 2.4 MW-AC SunPower PV generator.
Two previously installed energy storage systems will be integrated into this microgrid project. The campus has a STEM PowerStore 5.3 lithium-ion battery system located in Bech Hall parking lot with a rated capacity of 1MW/2MWh. This existing battery energy storage system (BESS) primarily provides demand charge management, which lowers the campus monthly electric utility bill from PG&E. The college also has an existing thermal storage device, an ICE Bear Thermal Energy Storage System, which provides hour of chilling to meet a portion of the Doyle Library’s cooling load.
During the microgrid project, the campus will deploy two new Energport BESS’s, with a total of 2MW/2MWh capacity, which will primarily charge from renewable PV energy. The BESS’s will allow the campus to offset energy usage from the grid in times of peak demand and provide power to campus during grid outages.
The campus microgrid system will include load shed and automated disconnect switches to allow the microgrid system to prioritize loads in the case of an outage and isolate a combination of different buildings on campus in order of importance.
Each Energport battery will be connected to a GoElectric LYNC Secure battery inverter and will communicate directly with the PXiSE microgrid controller. The inverters are programmed to autonomously transition from Grid Interactive Mode to Grid Independent mode during a voltage sag. This auto-transfer capability will allow the microgrid system to quickly and seamlessly transition to islanding mode in the event of a planned or unplanned outage.