IEEE Power & Energy Magazine - November/December 2020 - 33

withstand associated voltage waveform disturbances, and
performance for various system conditions, such as a capability to withstand frequency rates of change and voltage
phase angle jumps.

o- perational performance requirements for disturbances to the
voltage (including multiple events) and the frequency.
Power Quality Modes
Although AS/NZS4777.2:2015 already addresses the power
quality response, at the time of its adoption, many of the
functionalities were novel and not widespread and thus
implemented only in an optional capacity. With the increasing DER penetration of the distribution grids, DNSPs are
now requiring the implementation of functions, such as
volt-var and volt-watt response modes, for new D-PVs,
which facilitates a more progressive reduction of the inverter
output as the voltage rises. Otherwise, the system relies on
overvoltage trip settings to manage local system operations
and increase feeders' DER-hosting capacities.

Next Steps
The suggested changes in this revision of AS/NZS4777.2 are
a first step toward a high-DER future by improving the autonomous behavior of associated systems. Further requirements
will be considered by AEMO through a staged approach,
such as active optimization through i- nteroperability, resulting
in a need for cybersecurity measures and increased coverage
beyond the LV network.
Larger Systems

According to the SAPN generator interconnection standards, it is a requirement for every generating system that is
net exporting more than 200 kW to the distribution network
to implement a cost-effective SCADA solution that has the
ability to carry out a control signal issued by SAPN and, at
times, under the direction of AEMO to manage system security. This may include curtailing the output of large asynchronous generation during periods of low minimum demand
combined with large D-PV outputs and -during -noncredible

1.10

Frequency: >50.25 Hz at 1:11:49 p.m., With
an Initial Peak at 50.45 Hz at 1:11:51 p.m.
Second Peak: 50.46 Hz
at 1:20:37 p.m.

Normalized Power
(MW/MW at 1:10:55 p.m.)

1.00

Frequency: <50.15 Hz for 60 s Beginning
1:23:59 p.m. and Ending at 1:24:59 p.m.

50.5

0.90

0.80

49.5
Frequency Minimum: 49.21 Hz at 1:11:46 p.m.

0.70

Frequency (Hz)

Protection and Control Functionality
The unpredictable behavior of D-PVs following disturbances has been identified as potentially resulting from the
lack of clear guidelines for performance, measurement, and
response during events that cause voltage waveform distortions. For the revised AS/NZS4777.2, the Standards Australia review is considering the inclusion of clearer specifications for the expected accuracy, including the ability to

0.60
1:34 p.m.

1:32 p.m.

1:30 p.m.

1:28 p.m.

1:26 p.m.

1:24 p.m.

1:22 p.m.

1:20 p.m.

1:18 p.m.

1:16 p.m.

1:14 p.m.

1:12 p.m.

1:10 p.m.

48.5

Australian Eastern Standard Time
AS/NZS4777.2:2015-Specified Response

AS/NZS4777.2:2015-Specified Response (1-min Average)

Observed Power: <30 kW, 1,557 Sites

Observed Power: 30-100 kW, 68 Sites

South Australian Frequency

50.25 Hz

50.15 Hz

figure 16. South Australia's post-2016 inverter-over-frequency-droop response during the 25 August 2018 event. The
average aggregate power is compared with a specified profile. For further details, please refer to "Technical Integration of
Distributed Energy Resources" in the "For Further Reading" section.
november/december 2020

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IEEE Power & Energy Magazine - November/December 2020

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