Coal, the biggest risk to grid security, not solar or wind

A new study has found that the biggest threat to network stability in Australia’s electricity grid comes not from an increase in renewables, but from the control settings on the dominant fleet of “synchronous generators” – namely the country’s coal and gas fleet.

The significant new study – submitted to government authorities, network operators and the market rule maker – was prepared by Kate Summers, an electrical engineer with Pacific Hydro, and energy systems expert Bruce Miller.

It suggests that an economist-driven decision at the start of the National Electricity Market in 1999 led to the adoption of a market-based system for ancillary services, in contrast to nearly every other market where frequency services are mandated with fixed contracts.

The perverse set of incentives and penalties has resulted in the “deadbands” of the crucial control systems either being relaxed or switched off, leaving the grid effectively at the mercy of unforeseen events, because the assumed back-up or quick response is either too slow or non-existent.

It says these settings leave the power system exposed, particularly to a series of successive small events, and may have been a contributing factor to the major September 28 blackout in South Australia, even though the issue was not even considered in the subsequent analysis by the market operator.

And because fossil fuel generators now have limited response or are unable to respond quickly to changes in frequency, the market operator is sometimes left with only one safety net option: load shedding of the sort that has caused such controversy in recent months.

“This should be a wake-up call that there is something seriously wrong in the NEM (National Electricity Market),” the report says.

“Given that a region has suffered a system black and the analysis to date has failed to question the logic of allowing local governors to be disabled or detuned to be made unresponsive, it is a sign that the prior emphasis on control philosophy has been lost,” it writes.

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Giles Parkinson