Power Quality Control Modes in Australia

This article applies to

This article outlines a brief introduction and explanation of Power Quality Control Modes in the inverter settings and this is only for Australia and New Zealand. There are 4 modes but we only cover Volt-Watt and Volt-Var Response modes here. For more details, please refer to AS4777.2-2020.

What are Power Quality Control Modes?

The Power Quality Control Modes are internal inverter settings that were introduced in AS4777.2 - 2014, and will be activated by default according to the standards. 

These will -  

1) Contribute to maintaining the power quality at the point of connection of the installation

2) Provide characteristics which are outside the typical operation of an inverter for the purpose of providing support to a grid

Why is it needed?

The output power of solar inverters vary over time as it depends on the amount of sunlight received. This means it is an uncontrolled energy source, which can destabilise the grid voltage, especially nowadays with more and more rooftop solar penetration happening across Australia. Therefore, it is very important to introduce the Power Quality Control Mode, mainly to help DNSPs (Distributed Network Service Providers) stabilising the network. 

How does it work?

- Volt-Watt Response Mode

According to the latest standard AS4777.2- 2020, this mode is enabled by default, and will reduce the inverter power output in response to an increasing voltage at the AC terminals of the inverter. The inverter is programmed so the behavior of output power and grid voltage is shown as following:

fig[1] Exact from AS4777.2 - 2020

• Australia A: For large interconnected power systems, e.g. the National Energy Market (NEM)
• Australia B: For small interconnected power systems, e.g. the South West Interconnected System (SWIS) in Western Australia
• Australia C: For isolated or remote power systems e.g. Horizon Power in Western Australia
• New Zealand: All systems in New Zealand

There might be different set points required for different sites, depending on the location of the job. DNSPs (Distributed Network Service Providers) will decide which regions their networks fall under. All system designers and installers should check the exact set points with DNSPs.

- Volt-Var Response Mode

The Volt-Var Response Mode varies the reactive power output of the inverter in response to the voltage at its grid-interactive port. The inverter will sink reactive power in response to an increase in voltage (inductive) and supply reactive power in response to a decrease in voltage (capacitive). The voltage at which the inverter should sink or supply reactive power at a given % of the VA rating of the inverter can be adjusted. Here's one example: 

fig[2] Exact from AS4777.2 - 2020

• Australia A: For large interconnected power systems, e.g. the National Energy Market (NEM)
• Australia B: For small interconnected power systems, e.g. the South West Interconnected System (SWIS) in Western Australia
• Australia C: For isolated or remote power systems e.g. Horizon Power in Western Australia
• New Zealand: All systems in New Zealand

There might be different set points required for different sites, which depends on the location of the job. DNSPs will decide which regions their networks fall under. All system designers and installers should check the exact set points with DNSPs.

For more information, please visit https://www.cleanenergycouncil.org.au/contact