The task of keeping the lights on in Australia’s main grid this past summer – in the midst of record temperatures and demand levels, and unprecedented bush-fires and losses from network and fossil fuel generator failures – was further complicated by two unexpected new problems, the loss of solar output due to smoke and dust, and the sudden loss of wind power in extreme temperatures.
The problems are identified in the Summer Operations Review, prepared by the Australian Energy Market Operator, which says that despite the extraordinary summer – ranging from extreme heat, mega-fires, and then flash flooding in some regions – the power system remained secure.
Two interesting new issues arose, however, that – unlike problems with fossil fuel generators and storm damage to networks – were not anticipated before the summer, and these related to the growing amounts of wind and solar output.
The biggest surprise came from what AEMO describes as “extreme temperature cut-outs” from wind energy – which it says were experienced, for the first time, at a large scale across both South Australia and Victoria on a number of occasions.
The most notable of these was December 20, at the tail-end of an unprecedented heatwave, and on a day when temperatures reached 45°C in Adelaide and 43.5°C in Melbourne.
AEMO says the high temperatures of more than 40°C at the height of the turbine hubs (some of them more than 100m high) led to “high temperature cut out” of the equipment on top of the turbines.
The problem was particularly acute in Victoria. Even though wind speeds remained reasonably constant throughout the day, wind output in that state fell by around 800MW between noon and 5.30pm, which – combined with record levels of demand – resulted in AEMO contracting, although not activating, emergency reserves as it feared a lack of adequate supply.
This graph above illustrates the issue. Orange and purple represent the output from different regions in Victoria, while green is the average windspeed and red indicates the average temperature.
The high temperature cut-outs occurred again on January 31, although this time it was accompanied by periods of both high winds and low winds and network outages in a highly volatile day that eventually saw storms tear down the main link between Victoria and South Australia, leaving the latter state to operate as an effective energy “island” for more than two weeks.
This was not the only new curve-ball that added complexity to the grid operator. The smoke and haze caused by the massive bush-fires across the country in December and January, along with high dust levels, led to a decrease in output at times of between 6 per cent to 13 per cent from grid-scale solar farms. Similar impacts were felt on household rooftop PV.
The problem with these events affecting wind and solar are not that they occur, it’s the difficulty in forecasting them. The grid is already managed on the assumption that large scale coal and gas plants can, and do, suddenly trip, or that power lines can be at risk in extreme weather.
What AEMO needs is greater predictability. For the smoke issue, it is now looking at obtaining satellite imagery, updated numerical weather modelling, and enhanced personnel training to ensure smoke risks are understood and well forecast.
For the wind problems, it is looking for manufacturers to be upfront and more communicative about the risks of de-rating, just as the owners of the grid’s coal and gas plants – that are equally if not more vulnerable to falls in output in extreme weather – have already been asked to do.
AEMO says the last summer – which was Australia’s second warmed on record, and featured record demand (38.05GW on January 31) also experienced a record number of transmission separation events (six in all), a record number of “unplanned transmission outages” (see table below), and a record number of market interventions – most to deal with the lengthy separation of South Australia when the storm blew down the main power lines.
And the coal and gas generators also wilted in the heat, posting their own record loss of generation over the summer. “Consistent with previous extreme heat events, conventional generators experienced material output deratings,” AEMO said. Emergency reserves had to be called in NSW on two occasions because of the unplanned loss of coal and gas generators.
AEMO chief executive Audrey Zibelman said the experiences of the last summer heightened the need for more resilience, and fit-for-purpose regulatory arrangements on the grid, as the climate conditions will get worse.
“Australia’s physical electricity infrastructure is being increasingly challenged by longer lasting and more extreme climatic and bushfire conditions, which threaten and degrade transmission and generation infrastructure, as well as create forecasting challenges as fire, ash, smoke and haze impact transmission networks and solar output,” the statement said.
“Despite unprecedented challenges, power system security was maintained,” Zibelman added. “This outcome was achieved through having sufficient reserves available throughout the summer and a great deal of hard work across the industry to manage through a number of very complex and challenging climate-related events.
“What’s clear from our experience last summer, is that planning is essential and it’s critical for AEMO with governments, industry and other stakeholders to assess how we can best assure the resilience of Australia’senergy infrastructure to these rare but extreme the events.”
These include new interconnections between states, integration of wholesale demand response, more flexible market design and interim reliability measures agreed by energy ministers in March. Zibelman said that this will add resilience as well as deepen competition, ensuring the energy system’s ability to manage extreme weather shocks is cost-effectively enhanced.
She also pointed to the fact that regulatory processes need to better consider resilience benefits in network projects. The failure to do this has already prompted the South Australia and Victoria government to fast-track measures to boost energy security, going outside of the normal regulatory investment tests.
They are seeking to catch up with West Australia, which is not lumbered by the same regulatory restrictions because it has a separate grid.
