IEEE Power & Energy Magazine - September/October 2021 - 79

appliances, such as air conditioners and pool pumps, are also
highly represented in Western Australian households and
offer the potential for load management. For instance, in 2014,
an estimated 88.5% of homes had at least one air conditioner.
The Challenge
The isolation of SWIS and the rapid increase in uncontrolled
rooftop solar PVs means that the challenge of integrating
renewable energy is being experienced ahead of most
other electricity systems around the world. Rooftop solar
can already supply nearly 50% of instantaneous underlying
demand at times. Unlike other grids, SWIS is unable to rely
on interconnections for system support services to maintain
voltage and frequency when there is a large contribution
from nonsynchronous intermittent generation.
The impact of rooftop solar PVs and other DERs is amplified
in the islanded microgrids throughout Horizon Power's
service area (i.e., outside SWIS). Currently, PV hosting capacity
limits have been introduced in several microgrids, leading
Horizon Power to explore ways to increase hosting capacity
through actively managing this resource in the Onslow
microgrid (see " Onslow DERMS: DER Integration in Action
in Western Australia " ).
The SWIS daily load profile, which represents the energy
drawn from the grid by customers, has evolved in recent
years to resemble a typical " duck curve " (Figure 3). Energy
generated by rooftop solar PVs is leading to low grid-supplied
electricity demand in the middle of the day and a steep
ramp-up in demand for the daily evening peak as PV system
production decreases at sunset.
In March 2019, AEMO released a report, " Integrating Utility-Scale
Renewables and DERs in the SWIS, " that identified
forecast trends in midday low-load conditions as a significant
problem with market efficiency and system stability. As highlighted
earlier, AEMO forecasts that the critical minimum de -
mand at which technical limits are breached (around 700 MW)
could potentially be reached as soon as 2022. As well as presenting
risks to the overall energy system, the unrestrained
flow of solar energy onto local distribution systems, which were
originally built for single-direction energy flows, is increasingly
causing network operator issues on the distribution network.
Also, increased output variability caused by cloud bands
can cause rapid changes in output from rooftop solar PVs,
which results in the need for other generators to respond.
As the size of the rooftop PVs and the proportion of instantaneous
load it serves grow, there is an increasing need for
fast response support that can represent more than 25% of
underlying demand within very short periods.
The DER Roadmap
The Western Australia government responded to this rapidly
approaching challenge by launching the Energy Transformation
Strategy. This also addressed the opportunities presented
by the transition to renewable and distributed energy technologies.
The strategy contains three interlinked pieces of work:
✔ a new market design, to respond to the need to integrate
high levels of renewables
✔ the Whole of System Plan, to identify through scenario
modeling the least-cost investment required
in large-scale generation, transmission, and energy
storage and to identify emerging challenges for SWIS
over a 20-year horizon
✔ the DER Roadmap, to safely and reliably integrate
customer DERs in SWIS.
Cumulative Installed PV Capacity in Western Australia (System Capacity <10 kW)
1,400
1,200
1,000
800
600
400
200
Total Solar PV Capacity (LHS)
Monthly Solar PV Installations (RHS)
10
15
20
25
5
figure 2. Installed solar PV capacity in Western Australia. (Source: Australian PV Institute Solar Map, funded by the Australian
Renewable Energy Agency, accessed from pv-map.apvi.org.au on 8 December 2020.)
september/october 2021
ieee power & energy magazine
79
Installed Capacity (MW)
January 2007
July 2007
January 2008
July 2008
January 2009
July 2009
January 2010
July 2010
January 2011
July 2011
January 2012
July 2012
January 2013
July 2013
January 2014
July 2014
January 2015
July 2015
January 2016
July 2016
January 2017
July 2017
January 2018
July 2018
January 2019
July 2019
January 2020
July 2020
Monthly Installation Rate (MW/Month)
http://pv-map.apvi.org.au
IEEE Power & Energy Magazine - September/October 2021

Table of Contents for the Digital Edition of IEEE Power & Energy Magazine - September/October 2021
