Where should you start when looking at the options a community might consider?
This is about some of the technical information we tracked down at the start, but an equally good place to start might be the knowledge resources on this site.
In the first instance we looked for:
- network data
- energy consumption data
I've written more about how to go about collecting this data here.
We can look up Venus Bay on the AREMI map of renewables, add the layer of 'network opportunities' under electricity infrastructure and the map that is revealed (the header image of this blog) tells us that Venus Bay is served by the Wonthaggi Zone Substation (capacity around 40MVA)
A more useful insight was given by the rosetta portal for Ausnet Services. Ausnet are in charge of the distribution system for easter Victoria and so they look after the poles, wires and transformers (also called distribution substations) in Venus Bay. In my recent talk I described the 66kV system (red) as a highway. There is a 66kV extension to the Bald Hills Wind Farm but the only way that energy feeds Venus Bay is through the 'off ramp' at the Wonthaggi Zone Sub Station and then along the main roads (purple, 22kV, medium voltage (MV)) back via Inverloch to Venus Bay and Tarwin Lower. These two towns are at the end of the line.
Any detailed information about the Low Voltage (LV) system rests with Ausnet Services. Low voltages are 415V if you receive three phase power and 240V if your power supply only comes from one of those three phases. It is low voltage power that is distributed throughout Venus Bay. Typically a string of 10-50 houses will be connected to the same low voltage 'street' (to continue the highways and main roads metaphor), or a small group of shops. A single large IGA might have a dedicated transformer.
We don't yet know how much low voltage information will be useful for this project. We can get a rough idea by walking the streets and looking at who is connected to which pole. There is emerging enthusiasm for shared batteries at the low voltage level to balance the glut of solar energy some places are generating. We may well need to know more at the low voltage level to explore these ideas.
Energy Use Data
Getting energy use data required a signed data licence agreement with Ausnet Services and they are allowed to charge for the time taken to retrieve such data from their system. In Victoria they can aggregate Smart Meter data and provide a total consumption figure without betraying any individual customer privacy. Aggregated data does involve some effort though, as the person collating the data first has to identify all the National Meter Identifiers (NMIs - the unique number associated with each meter), extract the data and then compile a total.
(As an aside, I will do post on looking at your own Smart Meter data via the Ausnet portal - well worthwhile if you want to understand some of the detail about how you use energy.)
In our case we identified a SCADA (Supervisory control and data acquisition) point halfway along the road from Inverloch and obtained data from this unit. The SCADA points are one of the key ways Ausnet know what is happening on their network in real time. Ausnet kindly aggregated the smart meter data from Tarwin Lower and deducted it from the SCADA data to give us reading for Venus Bay.
This method isn't perfect because there will always be a gap between the bottom up data (smart meter data for every household and business) and the top down (SCADA) data. Some can be explained by unmetered loads like streetlights. Some might be energy lost in the system, particularly transformers, which lose around 2% of the energy running through them.
The graph below shows a semi-transparent trace for every day of the year. Where the traces overlay to make brighter colours, you can see which month has fairly consistent load profiles each day. The reason I used these traces rather than averages is to see how the extreme days create very different load profiles to everything else. They are faint and somewhat hard to see but the information is there.
Another way of looking at the Venus Bay load is to focus on the profile when a whole season is averaged and set at 1 for peak load (normalised). Three peaks to note:
- near midnight is hot water (controlled via the smart meter to come on in the night)
- morning is breakfast time with some extra heating on chilly winter mornings
- the evening peak is associated with dinner and arriving home
- summer is different in Venus Bay due to the holiday traffic