Half a million homes and businesses in Victoria were left without power late on Tuesday following a major power outage. The disruption occurred when severe winds knocked over several high-voltage electricity transmission towers, causing all four units of the Loy Yang A coal-fired power station to trip and go offline.
Victorian Energy Minister Lily D’Ambrosio described the blackout as “one of the largest outage events in the state’s history”.
The event has prompted questions about the reliability of the state’s electricity grid. But it’s important to note these extreme winds would have seriously disrupted any power system. It has little to do with the mix of renewable energy and conventional fossil fuels.
As climate change worsens, we have much work ahead to ensure our electricity grids cope with severe weather events. But in this case, the fact that a complete system blackout was avoided is a testament to the resilience of the system.
A day of wild weather
An extreme storm, including strong winds and lightning, tore through Victoria on Tuesday afternoon. It caused two transmission lines near Geelong to collapse, prompting several generators to disconnect from the grid and cutting power to parts of the network.
Other customers lost power after the Australian Energy Market Operator (AEMO) ordered “load shedding”. This involves temporarily cutting off electricity supply to some customers to keep the network stable and prevent damage.
According to a statement from AEMO, the storm also damaged hundreds of powerlines and power poles, and restoring electricity to all customers “may take days if not weeks”
What happened at Loy Yang A?
The disruption to electricity transmission caused AGL’s Loy Yang A generator to go offline. This was an automatic response known as a “fault ride-through” mechanism. It’s much like a fuse blowing if you have a short-circuit at home.
When large electricity loads are rapidly and unexpectedly removed from the system, electricity supply and demand are no longer matched. It’s a dangerous situation and means electricity generators can be badly damaged or even destroyed if they don’t disconnect from the network.
It appears that Loy Yang A was the first generator to disconnect. The effect was to reduce supply and help bring the system back into balance, preventing a system-wide outage.
All generators have protection systems that stop them from being damaged in these kinds of events. Loy Yang A tripped up to protect itself from permanent damage and in doing so actually kept the system stable. It did what the system is designed to do.
What part did renewables and coal play?
When transmission lines fail, the whole system is affected. This includes all types of generators – wind, solar, gas, hydro, and coal. The power outages on Tuesday were unrelated to the proportion of renewables and fossil fuels in the energy mix.
It’s possible that old coal power generators are more sensitive to transmission disruptions than newer technologies. But it’s far too early to say whether this had anything to do with Tuesday’s event.
Battery storage may have helped steady the grid. Batteries have ultra-rapid responses to these kinds of disruptions and can add or subtract power from the grid within milliseconds to keep the grid stable.
And looking ahead, one benefit of renewable energy systems is that they tend to be much more widely “distributed” geographically than coal generators. So when power lines go out, having a more distributed network actually provides more resilience.
Lessons from South Australia
In September 2016, wind storms in South Australia also blew over transmission lines. Cascading disconnections by generators meant the entire grid went black in a matter of seconds, causing a statewide outage.
It will take months to analyse all the data from the Victorian blackout. But it may well show that the lessons learned from the SA blackout saved the Victorian grid.
For example, AEMO was reportedly unaware about the exact settings of “fault ride-through” mechanisms on wind farms before the SA blackouts. This has since changed and may have helped minimise the impacts in Victoria.
A warmer future
We know more severe weather events are predicted under climate change. It will manifest in many different ways: strong wind events, heatwaves, bushfires, and floods.
All infrastructure, but especially energy infrastructure, is vulnerable under these conditions. It means all of us – researchers, market operators, and generator operators – must work hard to make energy systems more resilient as we move into an uncertain future.
This article was originally posted on The Conversation and has been republished here with permission.
About our Guest Author
 |
Dr Roger Dargaville is the Director of the Monash Energy Institute.
He is a senior lecturer and researcher in renewable energy in the Monash University Civil Engineering department. He is an expert in energy systems and climate change. Roger specialises in large-scale energy system transition optimisation, and novel energy storage technologies such as seawater pumped hydro and liquid air energy storage. He has conducted research in global carbon cycle science, simulating the emissions of carbon dioxide from fossil fuel and exchanges between the atmosphere, land and oceans as well as stratospheric ozone depletion. You can find Roger on LinkedIn. |
It shows our energy system is becoming more and more fragile as we remove reliable coal fired power stations and replace them with distributed renewables that require significantly lengthy transmission networks and interconnectors with other regions that significantly expands the area of risk.
It doesn’t show that the system is becoming more and more fragile at all. What bit of six of ten coal generators going offline don’t you understand.
Three years ago, a failure at one 400 MW coal generator in Queensland caused 2,400 MW of other generation to go offline and 400,000 customers to be disconnected.
In this case Victoria had sufficient reserves so that even though 2,960 MW of its coal generators were offline, within two hours of the incident all load shedding had been reversed and it was already exporting power.
The average transmission distance is falling as rooftop solar has near zero reliance on transmission and all of Northern and Western Victoria and even western Melbourne is closer to generation than it has ever been. More interconnectors allow diverse transmission paths so in fact reduce risk, particularly as the average load on interconnectors is declining
Try comparing like with like.
SA and Victoria both had massive blackouts across the state because they don’t have sufficient reliable generation and strong winds brought down the distribution network. Victoria was extremely close to having a system black event and things becoming significantly worse than they were. The risk of this happening again in SA, Vic and Tasmania is much higher as we rely on thousands of kilometres long transmission systems to get power from distributed renewables and don’t have sufficient synchronous generation located close to load centres.
On the other hand QLD had a catastrophic failure at an actual generation plant which of course affected the other units at the plant taking them offline. Meanwhile the majority of the state was unaffected. The Callide failure was not caused by a weather event and the risk of it happening again is extremely low.