IEEE Power & Energy Magazine - July/August 2021 - 43

the requirements of the network, and rewards customers
for their efforts to support the network with issues it faces.
The Australian Renewable Energy Agency-funded project
has attempted to address this by developing and trialing
the following in a real-life demonstration:
✔ a distributed optimization solution to coordinate
34 prosumers as a network-aware virtual power plant
✔ nonlinear pricing schemes that reward prosumers
for providing network support in a way that fairly
allocates benefits across all prosumers.
Project at a Glance
The project, also known as the Bruny Island Battery Trial,
is where this DER-led transformation of the Australian
distribution grid meets our little Tasmanian island community
(see " The CONSORT Project Fact Sheet " ).
The project's main aim was to investigate the use of prosumerowned
batteries and rooftop solar to simultaneously provide support
to the distribution network on which they are located and
add value to their owners. Bruny Island offered the perfect case
study and trial opportunity (Figure 2). Thirty-four Bruny
Island households received a subsidy to buy a solar battery and
an EMS that supports time-of-use shifting. Once installed, these
DERs contributed to reducing the household's energy costs and
were incentivized to coordinate and reduce the peak load, stretching
the undersea electrical cable thermal limit. This resulted in a
33% diesel reduction over the trial, with around 4% of feeder customers
participating, and a yearly average of AU$1,105 savings
per household, including network support payments.
The CONSORT Project Fact Sheet
* What: DER coordination for network support
* Funding: AU$2.9 million from the Australian Renewable
Energy Agency
* Project timeline: 2016-2019
* Project partners
° Universities: Australian National University, University
of Sydney, and University of Tasmania
° DNSP: TasNetworks
° EMS provider: Reposit Power
* Feeder: 800+ customers, 11-kV MV, and 0.4-kV low
voltage (LV)
* Holiday peak demand: 1,500 kVA in mornings and
evenings
* Undersea cable operating rating: 64 A and ~1,200 kVA
* Diesel generator rating: 550 kVA
* PV battery systems: 34 totaling 128 kW/333 kWh
* Supported load peaks: 16 peaks over 65 days
* Diesel reductions: 33%
* Customer interviews: 100+
figure 2. The Bruny Island 11-kV medium voltage (MV) network.
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43
Diesel
PV + Battery-Equipped
Participants
Beyond the specifics of the Bruny Island case, the project
was able to demonstrate a solution to some of the main challenges
underlying an effective transition to a DER-rich distribution
network. One such (technical) challenge is to coordinate,
in a nonintrusive way, the actions of multiple DERs
owned by self-interested prosumers to minimize the cost of
keeping the network within its technical limits.
We investigated an approach to this called network-aware
coordination (NAC), which uses locational marginal prices
(LMPs) to solve an unbalanced three-phase ac optimal
power flow (OPF) problem in a distributed manner. It leverages
the EMS to distribute computations among the households
and address privacy and scalability concerns. Such
distributed approaches have been featured in the literature
for some time, but this project is, to our knowledge, the first
demonstration of their ability to solve a significant problem
in real-world operations of a distribution network and the
challenges they face going forward.
Another important factor is to understand how to reward
prosumers for the support their system provides. While
mechanisms such as NAC can price the economic cost of
providing congestion and voltage support at each node of the
network, they raise equity and fairness issues when applied
to prosumers. An alternative solution, trialed in the Bruny
Island project, is to use reward structures rooted in cooperative
game theory.
Undersea
Cable
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