A new grid bridging system will help reduce fuel cost in remote communities
December 2, 2023
By Yuri Bult-Ito
ACEP, AVEC and Freqcon staff troubleshoot the GBS modules in the ACEP Energy Technology Facility lab.
Two remote communities on the Yukon River near the west coast of Alaska received a new grid bridging system, or GBS, which is designed to help them use more wind power, reduce their fuel consumption and save money.
St. Mary’s and Mountain Village have no road access and are powered by interconnected wind-diesel microgrids that are not connected to any other power system.
A GBS is a short-term energy storage system that is designed to allow costly diesel generators to turn off for periods of time and to run on renewables to reduce fuel consumption.
The 900-kW EWT wind turbine, installed in St. Mary’s in 2018 which serves both communities via transmission line, often has the capability to produce enough power to provide all or most of the electric demand. When there is sufficient wind power, the GBS is designed to allow for no diesel generators or only require smaller diesel generators to run online. This will enable more wind energy use and less fuel consumption in those communities.
“It’s been a long road to get to this point,” exclaimed Jeremy VanderMeer, a researcher at the ҹɫ Alaska Center for Energy and Power. ACEP is one of the partners of the GBS project, led by the .
The “long road” began four years ago, with modeling of the two communities to determine the value of a GBS and the technical capabilities that it should have.
The next step was to identify appropriate technologies. The project team investigated several technologies including ultra-capacitors, lithium titanate oxide batteries (or LTO batteries) and lithium iron phosphate batteries (or LFP batteries). An LFP battery was the final selection. While it was not as good a technical fit as an LTO battery, it had more energy capacity than required (one hour), was a much more common storage chemistry, and came in at a competitive price. Only a power application with minimum 10 minutes of energy storage is required in order to provide spinning reserves in small diesel microgrids.
Freqcon GBS modules outside of the ACEP Energy Technology Facility lab.
A GBS, manufactured by in Germany, arrived at ACEP’s Energy Technology Facility this spring for comprehensive functionality and performance testing prior to shipping to St. Mary’s. Freqcon’s GBS is a containerized energy storage system and has a novel “four-wire” inverter design. It requires no isolation transformer, resulting in cutting costs and lead time, and saving space and electrical losses.
“What followed was intensive testing and development work with staff from Freqcon, AVEC and ACEP, all working together to identify and solve control issues as they came up,” recalled VanderMeer.
While high quality, the GBS initially lacked some key functionality that is required to operate in small remote microgrids.
ACEP’s ETF laboratory was a perfect place for the testing — having access to electric loads with different power factors, electric loads that could be made unbalanced, different types of electric faults, a diesel generator and high resolution (including waveform) real-time data capture and display.
Full functionality achieved, the GBS units were barged to St. Mary’s in August, with commissioning and integration planned for later this year.
The St. Mary’s GBS is the very first energy storage inverter deployed in Alaska that can connect into the power system without a transformer.
The GBS project was led by in partnership with ACEP and , and funded by the , , and the through the program.
For more information about the GBS project, contact Jeremy VanderMeer at jbvandermeer@alaska.edu.