IEEE Electrification - December 2022 - 32

DER Management System
A DER management system (DERMS) applies to software
that can integrate the needs of utility grid operations with
the capabilities of demand-side DERs at the edges to support
multiple objectives related to distribution grid operations,
end-customer value, or market participation. In
practice, a DERMS platform implements control algorithms
and follows the five control architectures to manage gridedge
DERs. To meet the different requirements of the five
types of control architectures, DERMSs can be divided into
third-party DERMSs and utility DERMSs. In our opinion,
third-party DERMSs can be in the form of a building energy
management system, a microgrid controller, or a DER
aggregator. They are used to estimate DER flexibility by
applying analytics and control techniques, but typically
they have no or limited access to grid network information.
A utility DERMS is owned by the distribution utility and
coordinates the operations of third-party DERMSs by solving
a holistic optimization problem considering distribution
network information to gain system-wide benefits
from grid-edge DERs. Clearly, an effective and reliable
DERMS approach could help with the integration of DERs,
particularly at high penetration levels, and it could enable
the use of DERs to improve distribution grid operations.
Currently, DERMSs are still in the development stage in
the industry, and many functions are still evolving to
address increasing and new requirements for monitoring,
communicating with, and controlling DERs. But, in our
opinion, each DERMS should consist of three fundamental
modules: an aggregation module, a monitoring module,
and an optimal DER dispatch module.
1) An aggregation module first registers all DERs under
control and acquires the information on DER locations
and sizes.
DER
DER
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Control
Center
DER DER
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(a)
DER
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DER DER
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(c)
DER
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DER DER
(d)
Figure 2. Five types of control to aggregate and optimize grid-edge DER flexibility. (a) Centralized, (b) hierarchical, (c) decentralized,
(d) distributed, and (e) hybrid.
32
IEEE Electrification Magazine / DECEMBER 2022
DER
DER
DER
DER
(e)
DER
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Controller
DER
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(b)
Controller
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DER DER
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Controller DER
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Center
2) A monitoring module collects real-time DER inverter
outputs and grid measurements at all sensing locations.
3) An optimal DER dispatch module solves the optimization
problem by using DER information and real-time
measurements and sends the optimal operation set
points to the DERs.
Following this requirement, we have created a DERMS
prototype that adopts a distributed control algorithm. As
a demonstration of how a DERMS can reliably mitigate
the overvoltage issue, Figure 3 depicts the voltage profiles
for a bus location from a real distribution feeder in Southern
California under the day that experiences the highest
PV generation-to-load ratio. The performance of the
DERMS scheme is compared against the autonomous
volt-volt ampere reactive (VAR) control, where each PV
unit will provide reactive power responses according to
the Category A curve defined in IEEE Standard 1547-2018.
When setting the " watts priority, " the reactive power will
be reduced until the combination of active and reactive
power does not exceed the inverter capacity size if high
reactive power is requested by the volt-VAR curve, though
the " VAR priority " will curtail active power until the
requested reactive power is achieved.
As shown in Figure 3, when no action/control is taken,
the red line illustrates that overvoltages are experienced
for the interval from 8:00 to 15:00. The maximum value of
the voltage magnitude is obtained as 1.085 on one node.
The volt-VAR (watts priority) can enforce the voltage regulation
except for the period from 9:30 to 14:00. Because
the available reactive power is upper bounded by the
inverter total capacity and because this bound shrinks
with the increasing PV active power, the inverter does not
have sufficient reactive power between 9:30 and 14:00 to
support voltage regulation. The volt-VAR (VAR priority)

IEEE Electrification - December 2022

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