IEEE Electrification - December 2022 - 33

can actively provide reactive power support, but it can
only mitigate the violation at a certain level; however, the
proposed DERMS control can enforce the voltage regulation
and obtain a flat voltage profile during the periods
from 9:30 to 15:00. The profile is flat because the controller
is developed to guarantee the voltage regulation while
minimizing the amount of PV real power curtailment and
the amount of reactive power usage.
Example Applications of Grid-Edge Flexibility
Federated Architecture for Grid-Edge DER
Integration and Control
To enable the scalable aggregation and coordination of gridedge
DERs to support T&D grid operations, a federated
architecture is developed under the FAST-DERMS project
funded by the U.S. Department of Energy (DOE) Grid Modernization
Laboratory Consortium program. As shown in
Figure 4, this federated architecture consists of centralized,
hierarchical, and distributed control structures. It builds
upon the legacy T&D hierarchy, where the transmission
system operator or independent system operator (ISO)
schedules the bulk generation resources and balances the
transmission grid, and the distribution system operator
(DSO) manages its regional substations and their downstream
distribution grids to ensure a reliable power supply
to the end customers. To accommodate the integration and
coordination of grid-edge DERs, a new optimization and
control component, called the flexible resource scheduler
(FRS), is introduced to manage DERs within the same substation
service area. Multiple FRSs will exist to cover the
entire distribution system with multiple substations, and
they will be supervised and coordinated by a centralized
FRS coordinator.
Considering the complex ownership structures of gridedge
DERs, three different types of grid-edge DER control
are embedded in this architecture to aggregate DER flexibility:
direct control, aggregator control, and a transactive
energy market.
1) In direct control, grid-edge DERs that are owned or
operated by distribution utility companies can be controlled
directly by the FRS. Hence, direct control is a
centralized control method where the FRS serves as
the central controller.
2) In aggregator control, typically, most of the grid-edge
DERs are owned by private customers, meaning that
they are not likely to share confidential information
directly with the FRS. Aggregator control offers a
1.01
1.02
1.03
1.04
1.05
1.06
1.07
1.08
1.09
0.99
1
03:00
06:0009:00 12:00
Time
15:0018:00 21:00
No Control
Volt-VAR (Watts)
Volt-VAR (VARs)
DERMS
Figure 3. The voltage profile during the day that experiences the
maximum PV-to-load ratio on the node that suffered from the most
severe overvoltage of a real feeder in Southern California.
ISO/RTO
Generation Companies
DSO
FRS Coordinator
Substation
FRS
Substation
Substation
Transactive Energy
Market
DER
DER
DER
DER DER DER DER
Figure 4. A federated architecture for aggregating and managing grid-edge DERs to support T&D grid operations. FRS: flexible resource scheduler;
ISO: independent system operator; RTO: regional transmission organization; DSO: distribution system operator.
IEEE Electrification Magazine / DECEMBER 2022
33
Aggregators
Voltage Magnitude (p.u.)

IEEE Electrification - December 2022

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