After warning Queenslanders of possible blackouts, the Australian Energy Market Operator (AEMO) has said it was using its powers to direct electricity generators to avoid shortfalls.

The AEMO had issued a "lack of reserve" forecast for Monday afternoon and evening, meaning forecast demand was likely to outstrip supply in Queensland.

But in a statement issued at 5:20pm, it said it had invoked its powers under the National Electricity Rules (NER) and efforts had "provided sufficient generation to cover the lack of reserve 3 shortfall".

AEMO said it would "continue to monitor reserve conditions closely in Queensland, and more broadly across the NEM (National Energy Market), providing further updates should conditions change".

Earlier, Queenslanders were told they could face load shedding from 5pm until 8:30pm.

The AEMO had said if demand outstripped what was being generated, load shedding may have been used as a last resort.

In a statement, the AEMO said skyrocketing energy prices on Sunday had triggered an energy price cap, limiting the wholesale price of energy to $300 a megawatt hour.

"As a consequence, available offers from generators reduced, contributing to a forecast supply shortfall," the AEMO said.

AEMO said the market would be notified when the energy price cap was lifted.

'Thoughtful' energy use urged

Powerlink Queensland chief executive Paul Simshauser said the shortage was caused by a combination of events, such as the colder weather, which increased electricity consumption "higher than the median forecasts".

"On the supply side, there's a number of generators that are undergoing routine maintenance, but there are a couple that are on emergency maintenance as well," Mr Simshauser said.

He said there were as many as seven generators offline.

"It's not unusual to have three or four generators during this time of year, but we are up a bit on maintenance numbers," he said.

He said power supply was expected to be tight over the next couple of days until more generators were back online.

Where the power system was tight, Mr Simshauser was asking residents to be "thoughtful" with their electricity use.

"We're really only talking about two or three hours in the evening peak — so around about sort of 5:30pm to 8:30pm, and just in the morning," he said.

Mr Simshauser said rotational load shedding was unlikely as currently "the right generators are turning on at the right time".

"If there are any further mechanical breakdowns at any of our coal or gas generators, clearly that could change circumstances," he said.

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Associate professor of energy economics at the University of Adelaide Dr Liam Wagner said the lack of supply was of real concern.

"That has broader implications for the system stability and security of supply for electricity across the eastern market," he said. 

He said if it was not managed properly, blackouts could affect other states on the national energy grid.