What is load shedding and why does it occur

With hot weather set to continue for a few weeks yet, Origin is working hard to make sure our generation plants are in tip top condition, so they can play their part in keeping Australians cool.

On Friday 25 January 2019 thousands of Victorian households were left without power for several hours during a load shedding event – which is when power is cut to small parts of the electricity grid for a short time to avoid wide scale blackouts. We take a closer look at what caused this and explore the important role of the Market Operator in managing the country’s electricity system.

The Australian Energy Market Operator (AEMO) has the complex job of managing the National Electricity Market (NEM) which includes the generation, transmission and distribution of electricity across Tasmania, South Australia, Victoria, NSW and Queensland.

During the heatwave that rolled across South Australia and Victoria just before Australian Day, AEMO closely monitored available electricity supply and predicted the expected demand.

Late on Thursday 24 January, AEMO determined that there would be a shortfall in electricity supply of approximately 250MW during Victoria’s predicted peak demand period on Friday 25 January.

While Origin’s only Victorian generator, the Mortlake Gas Fired Power Station in the state’s west was running at full capacity throughout the heat wave, several generation units in the Latrobe Valley were off line. This was coupled with the predicted peak in electricity demand as Victorians switched on their air conditioners, creating a supply/demand imbalance.

To avoid a wide scale “blackout” (a complete loss of power) in Victoria caused by a system failure due to this supply/demand imbalance AEMO needed to act. They did this by directing Victorian distributors to schedule a series of rolling load shedding events across several Melbourne suburbs and Victorian townships.

In a statement issued on the morning of 25 January, AEMO explained that the scheduled load shedding was necessary “…. to maintain electricity supply and protect the power system as Victoria deals with record-breaking high temperatures, high demand and reduced generation availability.”

During the peak demand period, AEMO reported electricity load was shed impacting more than 200,000 consumers at any one time on rotation. By mid-afternoon as the cool change passed through Melbourne, AEMO directed distributors to restore all lost load.  

With summer set to continue for a few weeks yet, Origin is working hard to make sure our generation plants are in tip top condition, so they can play their part in keeping Australians cool.

If you’re electricity supply is unexpectedly cut, get in touch with your local distributor.

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