Failures at two gas fired generators contributed to fears electricity supply would be cut to NSW homes.
Failures at two gas fired generators contributed to fears electricity supply would be cut to NSW homes. Image Credit: David Seibold

The Australian Energy Market Operator (AEMO) has released its findings into a review of the electricity market in New South Wales when electricity supply was cut to industrial users during a heat wave on 10 February 2017.

Initial results indicate that failures at two gas-fired generators at a crucial moment contributed to the threat of electricity supply being cut from homes and businesses, as had occurred in South Australia on the day prior.

On 10 February, during an intense heatwave that gripped most of the state, AEMO ordered electricity supply to be cut to one of the state’s largest aluminium smelters in an effort to maintain a secure supply of electricity to customers.

According to the Bureau of Meteorology, on 10 February New South Wales set a new record for maximum temperatures across the state (42 degrees). This record was broken again the very next day, when state-wide temperatures reached 44 degrees.

AEMO cited almost record demand for electricity on the day, as consumption surged during the hot weather. The ability to meet the demand for electricity became challenging as the capacity to import additional electricity from Queensland and Victoria was limited, as the network infrastructure linking the states became overloaded.

Troubles at gas generators

Significantly, AEMO also noted outages at two gas fired generators, the 435 Megawatt Tallawarra power station and the 667 Megawatt Colongra power station, due to faults preventing each from coming online.

The Tallwarra power station “tripped” approximately an hour before load-shedding was required and was unable to supply any electricity for approximately 2 hours due to a fault in the gas generator.

After receiving instruction to commence operation, Snowy Hydro advised that it was unable to get the Colongra power station started, due to insufficient gas supply. Snowy Hydro had attempted to run the power station on diesel, but had again run into challenges in getting the generator started.

At the same time, output from solar and wind generators in NSW was in line with forecasts for the time of day. Additional supplies from Queensland and Victoria were overloaded, with imports exceeding the normal capacity of the network interconnectors with the states.

“These factors, all coinciding at approximately 1700 hours, combined to overload the New South Wales interconnections with Queensland and Victoria, creating an insecure operating state.” The AEMO report stated.

When load-shedding was required, electricity imports from other states filled the gap left by gas generators
When load-shedding was required, electricity imports from other states filled the gap left by gas generators. Source: AEMO

In the afternoon of 10 February, AEMO was forced to cut electricity supply to an aluminium smelter for just over an hour, reducing the overall demand for electricity by 290 Megawatts, to ensure stability of the electricity network.

While load shedding occurred in New South Wales on the day after it was also required in South Australia, it has received significantly less attention in political circles.

Load shedding in New South Wales was much larger than that required the previous day in South Australia. Where South Australian load shedding was conducted by cutting electricity supply to homes and businesses, in New South Wales, an arrangement was made such that a single industrial user, being the Tomago Aluminium Smelter, was the sole customer impacted.

As AEMO was able to proactively manage the electricity supply shortage, by entering into an arrangement with the Tomago Aluminium Smelter, it concluded that the market had operated as intended during the load shedding event.

Residents meet calls for reduced usage

Residents of New South Wales had been asked to limit electricity usage during the peak period on the 10 of February. An advertising campaign run by the NSW Government ask residents to limit usage of lights and electrical appliances, and to consider setting thermostats to 26 degrees during the heatwave.

AEMO believes that the campaign may have successfully reduced overall demand by an order of 200 Megawatts, ensuring that additional load-shedding was not required.

“AEMO has found generally that all actions and responses of facilities and services were adequate (operated as expected).” AEMO’s statement read.

A software fault in automatic load shedding software operated by SA Power Networks inadvertently took three times the number of homes off the grid. SA Power Networks subsequently offered an apology to the additional 60,000 homes that lost supply.

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