Team Developing Cyber-Secure Renewable-Intensive Microgrid

December 21, 2015 by Jeff Shepard

The Grid Integration Group at Lawrence Berkeley National Laboratory (LBNL) has been awarded a grant for a "Modular, Secure, and Replicable Microgrid Control System for Generation and Storage Management at Military Installations" at Fort Hunter Liggett by the Environmental Security Technology Certification Program (ESTCP), Department of Defense (DoD). The project has a total value of $13 million: $9 million provided by the site Fort Hunter Liggett in terms of equipment, and $4 million for the LBNL microgrid team to deploy a fully functional grid-interactive microgrid with seamless islanding capabilities. ESTCP was established in 1995 to promote the transfer of innovative technologies that have successfully established proof of concept to production use in the field.

The project is led by LBNL in collaboration with partners Alstom, EPRI, One Cycle Control, Microgrid Labs, Customized Energy Solutions, University of New Mexico, and Tri-Technic. The objectives of this project are to a) deploy and demonstrate a cyber-secure, renewable-intensive microgrid at Fort Hunter Liggett, and b) produce an interoperable control system that is commercial-ready for deployment on a rapid adoption roadmap.

This project will demonstrate key microgrid capabilities for managing the integration of diverse Distributed Energy Resources (DER) while providing resiliency against natural disasters with the capability to island for long periods of time when power from the grid is unavailable. In the event of grid disturbances or outages, Fort Hunter Liggett will be able to operate independently from the grid for a minimum of 120 consecutive hours, delivering a minimum of 1 MW load and 2 MW for 4 hours peak. This will be done using renewable-intensive generation, reducing fossil-fuel consumption (almost zero diesel use) while also reducing both emissions and costs. In the grid-connected mode, Fort Hunter Liggett will operate interactively with the grid, as a market participant for capacity and ancillary services.

Fort Hunter Liggett is part of a DoD initiative for net-zero bases, which will make the base a net-zero community with estimated 8 MW of PV and a 8 MWh battery system to serve the most critical loads. The batteries will be augmented by complex demand-response algorithms and building management systems as well as a bio-gas combined heat and power (CHP) generation system. The location of Fort Hunter Liggett at the end of a PG&E line can create difficulties if too much PV generated electricity is fed into the system. This problem has been addressed by line upgrades and a second feeder, currently under construction. To further support PG&E and the electric grid, the project will provide ancillary services when requested by the utility or CAISO.

The microgrid controller will have a multi-layered distributed architecture. In this control architecture tasks are distributed among four layers to ensure stable, reliable, and optimized microgrid operation: Layer 1 is a real-time device level control layer, acting in the micro-seconds to millisecond range that ensures stable and safe operation of the connected equipment and the network. This is realized through device level controls of DER, load, and feeder. Layer 2 is a network level automation and data acquisition layer, acting in milliseconds to seconds, to support cluster/plant-level operation.

Layer 3 is a supervisory controller layer acting in minutes to optimize the operation of the system as a whole in grid-connected and islanded modes. This layer includes generation, storage and load forecasting, data management, optimum operation scheduling, spinning reserve management, and automatic generation control. This layer is based on the DER-CAM microgrid optimization tool. And Layer 4 is a grid interface layer that supports grid interactivity and allows data transfer between the utility and the microgrid.

The microgrid controller will interact with the utility to react to dynamic prices, demand response signals, over-generation limitations, and the like. The multi-layered distributed microgrid controller architecture is being shared with the Working Group for the IEEE 2030.7 Standard for Specification of Microgrid Controllers.

In the microgrid concept design for Fort Hunter Liggett, the physical structure of the microgrid is modular. The design includes several substations that are connected to each other and to the utility through a MV cable ring. Each substation module includes PV generation, battery storage, and diesel backup generation to supply the building loads connected to it. This modular structure increases reliability and reduces maintenance costs for Fort Hunter Liggett. This project will advance microgrid applications to a new level of field-proven functionality and interaction with utilities and markets.