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Requirements for AS/NZS 4777.2:2015 compliant inverters

Western Power requires that the installation and connection of inverters used with solar photovoltaic (PV) systems and battery energy storage systems be compliant with Australian Standard (AS/NZS) 4777.2:2015, which relate to the grid connection of energy systems by inverters.

Solar energy system suppliers, inverter suppliers and electrical contractors must ensure they supply and install only AS/NZS 4777.2:2015 compliant inverters.

Functions offered by the AS/NZS 4777 inverter Standard are essential to ensure safe connection of inverter energy systems, including solar and battery energy systems, onto Western Power’s network. Functions provided by the new Standard will improve the customer system’s performance while not affecting the quality of supply to other Western Power customers. Configurations needed to enable inverter operation in compliance with the updated inverter Standard are described in Table 1 below.

When installing a new inverter system after approval the installer must choose settings compliant with AS/NZS 4777.2:2015 and Western Powers requirements. To minimise nuisance tripping of inverters the installers must check the following three items:

  1. Voltage rise within the customer installation is kept to a minimum. Maximum voltage rise within the installation is to be less than 2% or 4.8 V. Ideally, 1% or less voltage rise is recommended as this lessens likelihood of nuisance tripping
  2. The volt-watt power quality mode must be enabled with default settings as given in the Australian standard. This mode reduces the inverter power output when needed in order to prevent exceeding the voltage limits. If this mode is not enabled the inverter may experience frequent nuisance tripping when the network is lightly loaded.
  3. The setting for “sustained operation for voltage variations” is permitted to be set up to 258 V. This setting allows for approximately 4 V of voltage rise within the customer installation when the network voltage is at the upper limit allowable for Western Power.

Customer inverter installations that are affected by frequent nuisance tripping should be reported to the Western Power Fault line 13 13 51. The customer and installer need to confirm that the three points above have been addressed and that there is no other installation problem before calling the fault-line.

In some cases it has been reported that the inverters are not connecting due to the voltage being above 253 V. This is correct behaviour for the inverter and no settings need changing. After completion of an installation returning air conditioning, other appliances and load to their normal operating state will in some cases lower the voltage so that the inverter will connect. If this issue persists please call the Fault-line 13 13 51.

The inverter normally operates at full capacity depending on the weather conditions; however, it may operate at a reduced capacity at certain times of the year due to light load conditions and excess solar generation on the network. This will typically reduce export on to the Western Power network but continue to supply power to the customer’s loads. Conversely when high load conditions are present then the inverter should be able to supply the full customer load and export excess generation into the network.

Western Power will continue to take every opportunity to assist our customers and industry in the change to inverter energy systems which are compliant with the new edition of this Standard.

Western Power’s network voltage is a nominal 240 V and we have been and continue working to reduce the voltage level across our network to help accommodate more customer generation. Further notification/feedback from customers who are experiencing high voltage issues will assist Western Power to target areas that need to be prioritised.

Further information on connection of inverter embedded generation (IEG) is available in Western Power’s Network Integration Guidelines for IEG. This guideline provides network related information that should be taken into consideration for selection of suitable IEG systems at the start of the sales cycle. It also provides requirements for technical limits which can help avoid re-work during the connection process and improve customer service. The guideline also addresses connection of other technologies and inverter energy sources, as well as changes in the Standard mentioned above.

The guidelines are the result of working closely with industry sales executives, installers and engineers to improve the process to connect to the Western Power network and provide greater clarity for those wanting to adopt solar energy into their energy mix.

To access Western Power’s IEG guideline, please click here

TABLE 1 – Extract from Western Power’s IEG guidelines

Clause Comment Default setting Western Power requirement
6.3 Power quality response modes
6.3.2.2 Volt-watt response mode

Default - enabled.

Tables 9 & 10 of AS/NZS 4777.2 - default values.

Required by all inverters. Enabled for all inverters.

Tables 9 & 10 of AS/NZS 4777.2
- default values.

6.3.2.4 Voltage balance mode Default - disabled. Disabled for standard supplies.
Optional for customers with supplies > 100 A.
6.3.5
(6.3.5.3.2 &
6.3.5.3.3)
Power rate limit
Note: This will be applied to reconnection (i.e. ramp up/soft start).
Required.
Default ramp time
WGra=16.67%
Tn=6 minutes
Required.
WGra = 16.67%
Tn+=6 minutes
Protective functions for connection to electrical installations and the grid
7.3 Active anti-islanding protection Either test methods of AS/NZS 4777.2 Appendix F or IEC 62116. Test method to IEC 62116 is required.
7.5.2 Sustained operation for voltage variations Required.
Default setting of
Vnom-max = 255 V
Required.
Permitted setting range: 255 V to 258 V
7.5.3 Sustained operation for frequency variations (generation operation). Required.
Default setting
Fstop=52 Hz
Required.
Default setting
Fstop=51.5 Hz
Additional requirements for multiple mode inverters
6.3.5.3.4 Changes in energy source operation.
Note: For multiple mode inverters (i.e. with energy storage) will also apply for changes in energy source operation.
Default - disabled. Enabled.
For changes in energy generation and consumption through grid- interactive port.
6.4.3 Volt watt response mode for charging of energy storage Required. Required.
Table 9 and Table 12 of AS/NZS 4777.2 - default values.
7.5.3 Sustained operation for frequency variations (charging operations) Default setting
Fstop-CH=49 Hz
Required.
Default setting
Fstop-CH=49 Hz
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