Visualisations

In the National Electricity Market (NEM), power stations can bid in their availability in 10 different pricing tranches. They’re able to rebid this availability right up until dispatch is run.

Recently, I was exploring this bidding data and thought I’d take a peak at what the bidding behaviour of the Hornsdale (Tesla) battery looked like in the energy market.

I’d known for a while that the big batteries did a lot of rebidding, but I was blown away by just how frequent it was! In a single day (2019-01-01) the battery made almost 13,500 rebids! In fact, for the first interval of the day, the battery made almost 300 rebids in the week leading up to dispatch.

I do find it interesting how they appeared to be doing so many identical rebids – I suspect there must be some automated process going on that will rebid in all markets regardless of whether the rebid in a particular market is any different to the bid that it replaced.

One of the fun things about playing with hundreds of millions of rows of energy market data is that you can just go hunting through it for interesting anomalies. I recently found a fascinating anomaly exploring variable renewable energy (VRE – wind/solar farms) generation in Victoria on the 16th of November 2020

The figure below shows the combined output of every wind and solar farm in the state on a five minute basis between 11:30am and 3:30pm.

Lately I’ve been working with AEMO’s 4-second interval data from the National Electricity Market (NEM). Visualising the grid at this resolution is so fascinating, and I wanted to share a couple of figures I’d generated looking at the Hornsdale Power Reserve (the big Tesla battery). The figures have also raised a couple of questions for me which I’ve recorded below.

In all the figures, the battery has no dispatch target – rather it is responding to the automatic generation control (AGC) regulation instructions. In the figures:

• Left y axis:
  • MW is what the battery was doing
    • Positive values mean the battery is discharging
    • Negative values mean the battery is recharging
  • Target Ramp is the dispatch target of the generator
  • Target Ramp + Reg adds in the regulation component to the target
• Right y axis:
  • Hz is the mainland system frequency

On the 25th of May, an explosion and fire at Callide Power Station initiated a series of events that culminated in blackouts affecting hundreds of thousands of Queenslanders.

The figure below shows the coal power station units at Callide, Stanwell, and Gladstone tripping as this event unfolded between 1:45-2:10pm.

However, when I examined the two Gladstone units that did not trip, I saw something rather interesting. As you can see in the figures below, in response to a sharp drop in system frequency, both units momentarily boosted their output.

In July 2020, Melbourne entered its second COVID-19 lockdown – a lockdown which would not be lifted until late October. I thought it would be rather interesting to visualise the impact of this event on the number of PV system installations in each postcode of the city. These figures are based on the data provided by the Clean Energy Regulator which I merged with the spatial postcode data provided by the Australian Bureau of Statistics.

Pre-lockdown

Here’s how things looked in the months leading up to the lockdown – you can see how a few postcodes (in particular 3064 which appears to encompass Roxburgh Park) were having so many PV systems installed, I actually had to cap the maximum value of my heatmap at 300 so you could compare it to other postcodes in the figure.