Handbook of Energy Storage for Transmission or ... - W2agz.com

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3.2. DR/Peak Shaving
Description
By strategically locating BESS technology such as the VRB in the T&D system, utility
planners can efficiently manage load growth. Rather than constructing new substations
(or upgrading capacity in existing substations) to meet future growth, the planner can use
storage to add only the required “incremental” capacity, sized to serve peak loads for a
year or two. To further enhance its value, the VRB can be constructed as a
“transportable” BESS.
This use of storage defers T&D capacity additions, shifting substation capital costs into
the future. In cases where forecasted load growth does not occur, temporary BESS
installations would eliminate the substation capital expenditure entirely. Under this
strategy, where load forecasts are uncertain, storage would be used as a risk management
tool.
Whether temporarily deferring capacity upgrades or providing risk management, a
transportable VRB could be scheduled and moved to other locations on the utility system
as necessary. This strategy would allow the planner to target the most critical planning
areas, capturing multiple benefits over the service life of the BESS. Unlike other
generator technologies, the VRB can be easily sited with no emissions permits or fuel
handling (although local regulations and standards related to occupational health and
safety, materials handling, and transportation must be followed).
Alternatives
While other distributed resource (DR) technologies (such as diesel gensets and fuel cells)
can also provide peak shaving service, the primary alternative to the VRB is the
conventional method by which T&D planners provide for capacity: T&D upgrades.
These generally include new substations and substation upgrades, and may also include
line capacity increases.
Control/Dispatch Strategy
To maximize the peak power reduction for a given kWh energy rating, the VRB would be
controlled to follow load above a user-defined threshold load. This caps the load at the
threshold value and fully utilizes the energy storage capabilities of the battery.
The peak shaving technical requirements for interconnection and controls would be very
similar for customer peak shaving. For large industrial or commercial customers, the
VRB could be used to reduce the demand charges by capping load at a fixed threshold.
The system would be cycled for several weeks out of the year, depending upon the actual
loads relative to the T&D capacity constraints.
Vanadium Redox Battery 23