Australian utility Evoenergy is carrying out one of the most
comprehensive demand management trials ever in Australia, using a combination
of batteries and traditional demand response.
One of them, a virtual power plant used to avoid a
substation upgrade, could save Evoenergy around AUD $2 million (USD $1.6
million).
Evoenergy, an electricity and gas provider in the Australian
Capital Territory (ACT), has undertaken seven demand-management tests in the
last six months.
The largest of these, in February, involved three types of
participants: residential customers, contracted commercial customers, and
people with on-site battery systems.
During the trial, coordinated from the energy company’s
Canberra control room, Evoenergy sent participating residents text messages
asking them to cut their electricity use. Commercial customers were asked to
curtail loads or switch to alternative power.
The residential battery systems, meanwhile, acted as a VPP
dispatching renewable electricity into the grid.
Residents who cut their energy consumption in response to a
text message got no formal incentive; customers offering up their battery
systems for use in the VPP “were offered a payment,” said Glenn Pallesen,
acting general manager at Evoenergy.
In its multi-demand response test, Evoenergy signed up 402
batteries and linked them into the VPP through control systems belonging to
Reposit Power, Evergen and ActewAGL.
During the test, 367 batteries responded to a signal from
Evoenergy and dispatched energy into the grid.
The batteries delivered 570 kilowatts of power, which added
to 2.1 megawatts of curtailment from large customers that delivered 2.6
megawatts of demand response. Evoenergy said the trials had no negative impact
on the safety or reliability of the grid.
“At scale,” said Evoenergy, “we would be able to
strategically and quickly reduce enough load on the ACT electricity network to
avoid load-shedding in almost all circumstances.”
However, an analysis of trial results shows the impact of
curtailment by residents was minimal. In two tests carried out in September
2017, only 6 percent of customers in the trial area responded to a text message
from Evoenergy.
“We only expected to see a small impact,” Evoenergy
admitted.
A further test last month revealed potential limitations in
the VPP concept.
Working through Reposit Power smart controllers, Evoenergy
requested 333 battery systems to start discharging for an hour from 8 p.m. and
325 of them responded, delivering almost a megawatt to the grid. After 30
minutes, though, the power began to drop, ending at 600 kilowatts by the end of
the hour.
Evoenergy said the test yielded “the clearest result of the
VPP trials” because there was no PV generation at the time.
Nevertheless, once it is fully operational Evoenergy expects
the VPP to deliver power for one to two hours, Pallesen said. The experience so
far has given the power company the confidence to submit a substation deferral
plan to the regulator.
“In our most recent regulatory determination submission,
Evoenergy has included a demand response proposal to defer a
multimillion-dollar zone substation for two years, until 2025-26, through the
use of non-network demand management,” said Pallesen.
“This will involve the use of residential and network-scale
batteries in a geographically specific VPP for a new residential estate
development.”
By 2020, Evoenergy predicts more than 5,000 ACT dwellings
will have solar systems paired with batteries, capable of generating up to 36
megawatts or 5 percent of the territory’s peak load.
“This would be double the amount of load we curtailed, with
the support of the community, which prevented load-shedding during the heatwave
crisis in summer 2017,” said Leylann Hinch, Evoenergy branch manager, asset and
network performance, in a press note.
During the February 2017 heatwave, Evoenergy asked customers
to curtail 18 megawatts of power as peak demand topped 637 megawatts. It came
close to reaching 650 megawatts, which would have led to load-shedding.
“We avoided load-shedding then by going out to our major
customers and the public, requesting them to reduce consumption,” said Hinch,
“but we don’t believe it’s best practice to do this reactively during an
emergency, as the result is uncertain.”
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