Projects:2021s1-13013 Investigation of voltage control modes and strategy for large embedded generators connected to the distribution network with high penetration of Distributed Energy Resources

South Australia’s energy landscape is transitioning quickly from fossil fuel generation to renewable resources. Considering this, an increasing number of South Australians are opting to generate their power through Distributed Energy Resources (DERs). With a distribution network with one of the highest penetrations of DERs in the world, concerns about voltage control arise for the increasing popularity of connecting these DERs. All kinds of DERs contribute to this concern, and domestic rooftop solar can contribute to voltage rise issues as well as Large Embedded Generation (LEGs) which generate power in the range 200KVA to 5MVA. This project only seeks to mitigate to adverse affects of LEGS, and not domestic rooftop PV, although the impact of rooftop PV and the voltage complications caused by them must be considered. The connection of LEGs to a distribution network which is already saturated with DERs like rooftop PV means that there is more chance for voltage rise events to occur which, at the bottom line, leaves customers in that region without power. If LEGs are to be installed to the distribution network such that that the total electricity demand may be met, all customers who are wanting to connect are able to, and voltage remains at an acceptable level, then alternative hardware and control options will be necessary to support this. This interim report presents the project group’s initial literature review, current methods for voltage control in South Australia and method for testing alternative voltage control techniques such as reactive power absorption, injection and droop control by using the SA Power Networks (SAPN) distribution network as a case study. This interim thesis proposes that fixed voltage control, fixed reactive power control and fixed power factor control may be used as voltage control methods for categorised types of LEGs on a distribution network with a high penetration of DERs.

Introduction

The connection of embedded generating systems to the distribution network may impact on distribution utilities’ ability to regulate network voltages. For this reason, distribution utilities require embedded generating systems to consider voltage, power factor and reactive power control system as described below.

• Voltage droop control which varies by a fixed percentage to manage network stability.
• Operate at an agreed power factor such that voltage variations are maintained within prescribed limits.
• Control reactive power output, within their capability, to maintain the connection point voltage to anagreed target.Evaluate the ideal voltage control and methodology for large embedded generators categories connected to the distribution network.
• >30kVA & ≤200kVA (NER Chapter 5A assessment)
• >200kVA & <5MVA (NER Chapter 5A assessment)
• >5MVA (NER Chapter 5 assessment) (optional scope)

Project team

Project students

• Ishika Ghosh
• Georgia Kappos

Supervisors

• Mr David Vowles
• Dr Ali Pourmousavi Kani
• Mr Andrew Lim (SA Power Networks)