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Updated requirements for inverter energy systems

Updated requirements for AS/NZS 4777.2:2015 compliant inverters to be used on the Western Power network

We are introducing changes to our Network Integration Guideline that will require all new inverters to have 'volt-var' response mode enabled.

The new specifications will:

  • help connect new Inverter Embedded Generation (IEG) systems to the Western Power grid
  • improve customer experience following new inverter installations and
  • ensure balance in the network for ongoing solar installations.

We continue to require compliance with Australian Standard (AS/NZS) 4777.2:2015 (which relates to the grid connection of energy systems by inverters) for the installation and connection of inverters used with solar photovoltaic (PV) systems and battery energy storage systems.

Functions offered by the AS/NZS 4777 inverter standard are essential to ensure you safely connect inverter energy systems (including solar and battery energy systems) to our grid. They also ensure that your customer will get the best possible performance from their new inverter installation without affecting the quality of supply to our other customers.

The current requirements include:

  • AS/NZS 4777.2:2015 compliance
  • Anti–islanding protection function tested to IEC 62116
  • Activation of the “volt-watt” function using the default setting of AS/NZS 4777.2:2015

In addition to these, it is allowed for the sustained over-voltage setting to be increased to 258V where it's needed to prevent nuisance tripping and reduce any frustration that customers may have after the inverter system is installed.

The volt-var settings are designed to share the reduction of impacts across all installations while continuing to allow the customer to generate their own power into their premises and onto the grid.

When activated, the volt-var function smooths the grid voltages by using the customer’s inverter to absorb reactive power from the grid when voltage levels rise. Further to this, when voltages fall below (V2) 220V, the volt-var mode will cause the customer’s inverter to generate reactive power to support the grid voltage.

Western Power required volt-var settings from 9 August 2019

Reference value Required voltage value (volts) Reactive power required of inverter rating (p.u.) Var type
V1 205 0.3 Var source or generator
V2 220 0.0 No Var
V3 235 0.0 No Var
V4 250 0.3 Var sink or load

Please refer to inverter manufacturer instructions as to how to implement these settings.

The amount of reactive power absorbed or generated is in direct proportion to the inverter’s kVA rating and the grid’s voltage. 

Interaction of volt-watt and volt-var on IEG real power output

A graph showing the interaction of volt-watt and volt-var on IEG real power output

The graph above shows how the reactive power output of systems change based on voltage at the inverter terminals (orange line), as well as the impact on active power output when considering the volt-var settings in conjunction with the current volt-watt settings (blue line).

Also shown is how our proposed volt-var settings will have a minimal impact on customer’s real power production (blue line). The significant reduction of real power production is from the inverter’s volt-watt mode, which begins at voltages above 250 V and reduces real power output above this.

Our volt-var settings are matched to the Western Power grid so that as grid voltages rise due to increased PV penetration, we want volt-var to operate first, before volt-watt, therefore minimising the possibility of ramping back customers real power production for higher grid voltages.

Important dates to remember

  • 9 August 2019 - new inverter installations should have the volt-var power quality response mode enabled 
  • 1 November 2019 - new inverter installations must have the volt-var power quality response mode enabled - this will bring Western Power in line with national guidelines included in the ENA basic and LV connection guideline and assist with the ongoing uptake of these systems across the Western Power grid

For existing customer installations that are reporting voltage rise issues and have inverters that have the volt-var capability it's permitted to enable these volt-var settings to assist in potentially improving customers installation experience.

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