Late on Friday afternoon last week there was a significant AUFLS (automated under-frequency load shedding) event in the electricity grid of Great Britain. This sparked much discussion, online and offline, over the weekend between various groups of data junkies (myself included), and led to this somewhat-related article here on WattClarity also today.
Given these discussions, I thought it would be handy to publish openly here some of what we included within Theme 9 within Part 2 of the Generator Report Card for the Australian grid – as there do appear (at least on initial review) to be some significant similarities:
As illustrated, in Theme 9 we explored a number of different aspects of “Emerging challenges for managing system security” in Australia’s National Electricity Market (NEM), and the grid underneath that makes this market (or any form of dispatch) possible.
Amongst the different aspects we explored within this theme, we reverse-engineered the instantaneous provision of inertia in the grid “naturally” provided by synchronous generation in each of the regions of the NEM. In the following chart and discussion, lifted from the Generator Report Card (p33 of part 2 for those who have their copy) we show the MAX/AVE/MIN range apparent each month for the South Australian region:
Note for those who have more of a real life than us data junkies – inertia is commonly calculated in “megawatt seconds” (i.e. MWs). Also, those who are a little rusty might appreciate Jonathon Dyson’s handy explainer of why system frequency is so important, and also Allan O’Neil’s prior case study of what happens when a generator trips.
For illustrative purposes in the Report Card (and because it continues to be just so topical) we “zoomed in” to trend our calculation of the instantaneous level of inertia supplied by synchronous generation plant at the time of the SA System Black on 28th September 2016:
Apologies for feeling the need to be pedantic (triggered in part because of these two very vocal and far-too-influential groups ) but I re-iterate last week’s caution that this article is posted, and the details explored within the Generator Report Card, to in no way attribute “blame” for the events leading into the SA System Black.
It may well prove that there were similar contributing factors just experienced in the UK – though one would need to delve into the high-speed sub-second data from measurement points across the grid to really discern this. We’re sure that National Grid in the UK will be starting to do this for their report to Ofgem.
For those who wish to discuss this further, or more generally explore the insights shared in the Generator Report Card, these events in Sydney on Wednesday this week and Wednesday next week would be a good opportunity (or just let us know via this feedback form).