IEEE Power & Energy Magazine - September/October 2021 - 27

✔ system management, which includes
* procurement of reserves
* operational measures to ensure adequate system
security services are available during periods with
high levels of passive DPV generation online
✔ network development options helping to mitigate the
consequences of high DPV generation in the daytime
and reducing the likelihood of regions islanding from
the NEM. This can include the likes of building new
transmission lines or network resistor banks.
Looking to the Future
By 2025, the half-hourly generation from wind and solar PVs
(including DPVs) is forecast to regularly exceed 50% throughout
the NEM and at times reach much higher levels. If not addressed,
system limits will present barriers to the amount of wind and
solar generation that can securely operate at any one time.
Figure 10 shows the changing system conditions forecast in
the NEM from 2019 to 2025 (as in Figure 2). These are overlaid
with the system limits identified in the RIS Stage 1 study, which,
if not addressed, will create barriers to the proportion of wind and
solar PV generation that can securely operate at any one time. To
read Figure 10,
✔ the gray dots show the actual instantaneous penetration of
wind and solar generation in the NEM in 2019 and the red
and orange dots show the forecast instantaneous penetration
of wind and solar under the 2020 ISP Central and Step
Change generation builds
✔ Zone A indicates where DPV integration challenges
start to emerge
✔ Zone B indicates where managing variability and
uncertainty will become increasingly
challenging
✔ Zone C indicates where inertia
and system strength limit
impact secure operation
✔ Zone D is an aggregation of
the current minimum online
synchronous generation required
to meet system strength
requirements in each region.
Zone A represents where challenges
with accommodating increasing
penetrations of highly distributed
PVs start to increase. The
following measures stand out to the
authors as low-regret enablers to be
considered as early as possible in
the regional uptake of DPVs:
✔ establishing suitable visibility
of the distributed
fleet (initially static visibility
of what is installed and
eventually some aggregated
level of real-time visibility)
september/october 2021
35
40
30
25
20
15
02550
Zone A
Zone B
Zone C
Zone D
Solar and Wind Penetration (% of Underlying Demand)
75
2019 (Actuals)
2025 (ISP Central)
2025 (ISP Step Change)
figure 10. Increasing penetrations of wind and solar and zones where system limits
are likely to bind. (Source: AEMO; used with permission.)
ieee power & energy magazine
27
100
✔ DPV disturbance ride-through capability
✔ DPV capability to support grid frequency and distribution
voltages
✔ the ability to curtail or shed DPV generation for use if
extreme abnormal conditions (e.g., electrical islanding
of regions) arise during high-DPV generation periods.
There is also a need for system operators to maintain the effectiveness
of emergency under frequency load shedding and system
restart capabilities as DPV uptake reduces the availability of easily
forecasted and implemented load blocks during daytime hours.
Zone B highlights where wea ther variability and uncertainty
characteristics start to push up against operational limits
when balancing supply and demand. At the same time, system
flexibility is changing and needs to be actively managed
to ensure secure outcomes. Increases in system flexibility and
improvements in forecasting to reduce uncertainty, along with
operational improvements such as using a probabilistic forecast
as input to the generation dispatch, will be required to manage
the changing system.
To assess the ramping requirements and the system's
capability to respond across different time frames, new operational
tools and processes will be required. Appropriate
regulatory frameworks should also be considered to ensure
market signals align with this system need.
As the penetration further in creases into Zone C, the system
impinges on minimum inertia limits and the ability to securely
manage frequency stability. To successfully manage frequency
stability in the NEM in 2025, a minimum level of synchronous
inertia will be needed. A staged approach to reducing online
inertia is recommended to allow progressive adaptation of
system frequency control design. In parallel, essential system
A
B
C
D
Underlying Demand (GW)
IEEE Power & Energy Magazine - September/October 2021

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