SAPN – Impact of Distributed Energy Resources on Distribution System Quality of Supply

Overview

SA Power Networks is the distribution utility servicing metropolitan Adelaide and much of the state of South Australia.  The South Australian Distribution Code and the National Electricity Rules require SA Power Networks to meet specific criteria relating to Quality of Supply.

With recent and forecast increases in the penetration of distributed energy resources (DER) such as rooftop photovoltaic solar, SA Power Networks engaged PSC to assess the impact of DER penetration on Quality of Supply in residential low voltage and single-wire earth return (SWER) distribution systems.

Project Solution

The early stages of this project involved close collaboration between PSC and SA Power Networks personnel to develop a useful, technically sound scope. During this phase of the work, we selected test systems, built a sample feeder model, and selected scenarios of different DER penetration levels to be studied.

The SA Power Networks system includes approximately 70,000 distribution transformers. Working with the client’s Low Voltage Planning team and other internal stakeholders, PSC selected fifteen representative distribution feeders (twelve low voltage and three single-wire earth return) for modelling. These feeders would subsequently be modelled under various DER penetration scenarios, to assess three key Quality of Supply parameters:

  • steady-state voltage regulation
  • unbalance
  • voltage fluctuations

DER scenarios included various credible penetration levels of:

  • rooftop photovoltaic (PV)
  • electric vehicles
  • controllable load
  • battery storage

PSC Services

The PSC Power Networks team built models of the representative feeders in the DIgSILENT PowerFactory power system analysis package. The models reflected typical customer loads, and accounted for voltage unbalance identified in measurement data. Quality of supply parameters were determined across a wide range of DER penetration scenarios, with the impacts of increasing penetration of the different DER types being assessed against the requirements of the Code and Rules. Services provided included:

  • Project scoping
  • Specialist system studies
  • Specialist distribution network analysis
  • Specialist power quality analysis
  • Stakeholder engagement

Outcome

As well as providing SA Power Networks with a detailed report identifying the impacts of DER penetration on quality of supply, PSC collaborated regularly with the client, including delivery of regular workshops with SA Power Networks internal stakeholders.