IEEE Power & Energy Magazine - January/February 2020 - 68

An ADMS is an advanced version of a DMS, which includes all the
functionality of a DMS, while incorporating the future planning and
operational requirements of evolving power distribution systems.
program to reduce the computational requirements and
exploiting the observability of the network to aid the
solution process. Apart from developing adequate and
scalable OPF formulations, the availability of accurate
network models is equally crucial to ensure the valid-
ity of the calculated set points. Fortunately, distribution
companies are also becoming increasingly active in pro-
ducing and improving network models across all volt-
age levels. The combination of these efforts with rapid
advances in computing power means that using the OPF
as a decision-making engine for ADMS applications
could soon become plausible.
Various demonstration projects conducted worldwide by
industry and research institutions indicate that ADMS appli-
cations using the OPF can be implemented in practice. For
instance, a control room-like environment has been created in
the Smart Grid Lab at the University of Melbourne, Australia,
to showcase the maximization of energy harvesting of DERs
in MV and LV networks, as depicted in Figure 2. This type of
demonstration goes beyond traditional PC-based analyses by
creating a much more realistic testing environment using hard-
ware-in-the-loop simulation. In the United States, the Grid
Optimization of Solar project, led by the National Renew-
able Energy Laboratory and the Hawaiian Electric Company,
envisions OPF playing a vital role
in managing the ever-growing
adoption of solar generation in
Control Room
Hawaii. Several recently concluded
Environment
industry projects in Europe, such
as Grid4EU and IDE4L, have also
identified the effectiveness of
optimization-based approaches
in managing DERs in future
distribution systems. These demon-
strations also underscore the need
Hardware-in-the-Loop
for an adequate architecture in
Simulation
which these applications can be inte-
T/D Interface
grated into the ADMS. A potential
Custom-Built
MV Network
architecture is shown in Figure  3,
ADMS With
OPF Engine
where the OPF is built as a separate
functional layer on top of the exist-
LV Network
ing ADMS.
Although these efforts will
help boost the industry's con-
fidence in adopting the concept
of network-level optimization as
figure 2. A demonstration platform at the Smart Grid Lab. T/D: transmission and
distribution.
standard practice in future control

the network, or meet the required power factor at primary sub-
stations/transmission-distribution interfaces.
Lastly, given that, in practice, there are always multiple
stakeholders and/or considerations, the OPF can be adapted
to simultaneously consider other objectives deemed of
relative importance. For instance, renewable energy harvest-
ing can also consider the effects on losses by translating both
aspects into cost, thus allowing decision makers to deter-
mine the most optimal tradeoff.
There are also challenges that must be addressed
before ADMS applications that use OPF can be readily
deployed in control rooms. For example, new applica-
tions must be scalable to handle large, realistic distribu-
tion systems. The nonlinear formulation of classical ac
OPF makes it significantly harder to find optimal solu-
tions for large problems. Many devices (e.g., OLTCs)
may require integer variables to accurately model their
behavior, resulting in a mixed-integer formulation that
exacerbates this issue. Modeling all three phases of the
network is also crucial to cater to load and topological
unbalances, leading to a more than three-fold increase in
complexity due to coupling between phases. To this end,
innovative methods have been proposed by research-
ers, such as reformulating the OPF problem as a linear

68

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