Advanced Phasor-based Control of Energy Storage Microgrids
David Altman | Raytheon Integrated Defense Systems
This project will investigate the use of advanced phasor-based control to maximize the performance and reliability benefits of energy storage within a DoD installation microgrid. The investigators will apply phasor techniques, proven at the transmission level, to provide coordinated real and reactive power (PQ) control of fast responding energy storage units and other Distributed Resources (DRs) in a microgrid. By using affordable, scalable, Li-ion energy storage in combination with on-line market participation optimization, economics will be improved. The project will extend islanding coverage and duration through improved operation of DRs, accommodating stochastic dynamics of renewables and loads while maximizing DR efficiency. The use of small, N+1 redundant storage systems with grid-forming and Loss of Grid-Ride Thru (LoG-RT) capability in lieu of oversized diesel generation will improve availability, reliability, and ride-thru capability. The Phase I effort completes techno-economic and resiliency analysis to motivate a high-impact Phase II field demonstration. The project will also include high-fidelity Controller Hardware-in-the-Loop (C-HIL) testing of the control approach to substantiate its technical viability and better quantify projected benefits.
This project combines advanced phasor-based control with Li-ion energy storage to: 1) maximize energy storage value stacking opportunities and 2) improve microgrid coverage, availability, duration, reliability, and ride-thru functionality. We use Phasor Measurement Unit (PMU) data (available in modern relays) and high-speed communication to time-synchronize geographically distant real and reactive power measurements and create a complete representation of the power flow in the microgrid. Closed-loop feedback control provides decoupled real and reactive power (PQ) dispatch to diverse DRs in real-time to optimally manage load/generation balance during islanding. This contrasts with current practice where synchronized generators or a single inverter-based storage system handle high-speed control, and dispatch of other DR is handled on longer timescales. Dispatch commands to fast (e.g., inverter-based) and slower responding (e.g., diesel generator) DRs are partitioned using digital filters to achieve stable islanding, or meet a demand control objective at the microgrid Point of Interconnect (PoI). Market participation is optimized through coordinated DR control, informed by an on-line market participation optimization model. Our approach is compatible with modern off-the-shelf DR controls and uses utility-proven real-time data management software. N+1 low-cost Li-ion energy storage units provide grid forming and redundant LoG-RT capability. Reliable high-speed communication and control is assured through redundant control hardware and supported by extensive experience in highly sensitive transmission automation applications.
The project will quantify and substantiate the economic and resiliency benefits of incorporating energy storage in a microgrid. Through its advanced control capabilities, this approach opens the door to market participation opportunities that would not be feasible or economical for diesel generator-only or diesel + renewable microgrids. The techno-economic analysis will identify a broad spectrum of options ranging from behind electricity cost reduction to complex interactions that require a sophisticated understanding of the markets and dynamic market participation control to maximize revenue. The resiliency analysis will quantify improved critical load coverage probability achieved through optimal renewable utilization and improved microgrid DG reliability. The C-HIL testing will validate the ability of the approach to provide N+1 redundant, reliable islanding using multiple grid-forming storage systems sized as small as 15-20% of peak load. The C-HIL testing will also produce the performance data required to substantiate the viability of the proposed approach, and quantify its coverage, availability, duration, reliability, and ride-thru performance benefits relative to state-of-the-art control alternatives in a specific microgrid design.