IEEE Power & Energy Magazine - September/October 2021 - 85

align inverters with the required frequency settings of large
generation facilities in SWIS. It will ensure consistency across
all generators in response to frequency excursions. Inverter
capabilities to ride through short voltage disturbances are also
under review for inclusion in the standard revisions.
Other changes include an improvement to communications
functionalities. These are critical and foundational technical
requirements that will facilitate the future participation of
DERs by enabling the integration of aggregated DERs. The
roadmap looks to understand the net benefit of updating the
settings in the legacy inverter fleet (approximately 33% of the
installed inverters). Many existing inverters can perform in
line with updated standards, but they may require a firmware
upgrade accomplished either remotely or by an on-site electrical
contractor. The opportunity to target these inverters (particularly
in network locations where issues are emerging more
rapidly) is to be assessed by the distribution network operator
weighed against the cost of such upgrades.
Last, AEMO and other national Australian energy agencies
identified that as much as 40% of grid-connected inverters
for solar PV systems across Australia do not fully comply
with AS/NZS4777 and relevant distribution network service
provider connection agreements. The roadmap recommends
that a monitoring and compliance regime be further explored
for SWIS to ensure inverters are compliant with requirements
and can be upgraded as these requirements change.
Distribution Battery Storage
Storage is viewed as an essential component to ensure
power system stability and security in a high-DER environment.
Uptake of behind-the-meter storage is currently low
in SWIS as high technology costs and a flat tariff structure
have prevented storage systems from providing an attractive
economic proposition for households.
However, the use of front-of-the-meter battery storage in
the distribution grid provides an opportunity to unlock the
full capability of storage across the electricity service value
chain. They offer economies of scale for technology and
installation costs while presenting a chance for more efficient
coordination of storage capacity to provide broader benefits.
A distribution-connected battery can be located in areas
to provide localized network benefits. For example, batteries
can be operated to store energy generated by local solar
PVs and exported later during the evening peak. This can
help distribution feeders that are under thermal stress and
defer the need for costly network augmentation by reducing
energy flows across low-and medium-voltage distribution
transformers at these times. At sufficient numbers and
capacity, several distribution-connected batteries can be
coordinated to respond to broader system requirements and
deliver market services.
In SWIS, these benefits are not currently available to customers
who install behind-the-meter storage. Similar opportunities
are contemplated as part of the DER participation
theme discussed here.
september/october 2021
Under PowerBank trials recommended in the roadmap,
customers can share these benefits through " virtual " storage
products that allocate a share of excess solar generation
storage in a community battery for a daily fee. This
provides a cost-effective alternative to expensive behindthe-meter
storage while allowing customers access to value
streams they might otherwise be unable to access.
The roadmap recommends installing PowerBank batteries
to address localized network constraints with an attached
customer virtual storage product where possible, plus a
range of regulatory changes to facilitate the broader use of
distribution storage where efficient. As per the roadmap,
10 PowerBanks (each 116 kW/464 kWh) were installed in
2020 to provide network support. Consistent with the DER
Roadmap, Western Power has also released the " Distribution
Storage Opportunities " information paper to advise the
industry on future storage opportunities to provide services
to the network operator.
Grid Response and Power System Operations
High levels of DERs present challenges across the power
system. The physical limits of the low-voltage distribution
network infrastructure are being tested more frequently by
voltage fluctuations, which may require significant augmentation
and additional costs. The distribution network is also
constrained by a narrow voltage standard defined in Western
Australia legislation-a nominal voltage of 240 V ±6%
for 100% of the time. This differs from all other Australian
jurisdictions, which specify a nominal voltage of 230 V with
a wider tolerance of +10%/-6% for 98% of the time.
The increasing DER penetration causes suburban distribution
feeders to act as a net energy exporter at certain
times. This adds complexity to the management of the power
system. Increases in the variability of generation compound
the problem. Without adequate consideration of the magnitude
and direction of power flows at the distribution level,
the system operator is faced with significant risks during
system events.
To improve the ability of Western Power to manage voltage,
the roadmap recommends the urgent installation of
reactive power compensation (enacted by Western Power in
2020), and the amendment of the voltage standard in Western
Australia legislation to align with the Australian standard.
The roadmap also recommends the system operator's
dynamic modeling systems be enhanced to adequately
incorporate DERs. This is to be complemented by a review
of existing underfrequency load-shedding arrangements to
ensure they can maintain system stability on low demand
days, and revision of system restart arrangements.
Network Visibility
To manage the greater complexity for distribution network
operation, Western Power requires better visibility of local
power quality, flows, network constraints, and real-time
DER capabilities. To facilitate this capability, the roadmap
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