Renewables ‘can’t cope with sudden surges’
16 December 2016
Renewable power sources cannot cope with rapid or large changes in frequency, leading ultimately to a “black system”, a report by a national electricity regulator says.
The Australian Energy Market Commission’s draft report on power system security found the network is most secure when voltage and frequency are maintained by instantaneously balancing electricity supply against demand.
Large deviations or rapid changes in frequency can cause the disconnection of generation, potentially leading to cascading failures and ultimately a “black system”, the report warns.
South Australia was plunged into darkness on September 28 after storms knocked out transmission lines and the state’s wind-reliant grid couldn’t cope with the sudden, rapid and large deviation in frequency, tripping the interconnector with Victoria that it relies on for stable baseload power.
The report said spinning generators, motors and other devices synchronised to the frequency of the electricity system have in the past naturally provided the inertia necessary to allow the system to cope with uncontrolled changes in frequency.
But technologies such as wind or solar have no or low inertia and have limited ability to dampen rapid changes in frequency.
“Finding new ways to provide inertia and respond to frequency changes is where work is required,” commission chairman John Pierce said.
Federal Energy Minister Josh Frydenberg said the Turnbull government welcomed the report, as he yesterday stepped up attacks on Bill Shorten and “his mates in the Labor states” for pursuing unrealistic high renewable energy targets.
“They have failed to take into account the fact that the increasing amount of solar and wind power they are encouraging into the system is reducing energy security across the national electricity market,” he said.
“The increasing amount of solar and wind is creating a real challenge to the security of our nation’s electricity market, as they are non-synchronous generation technologies. In contrast, the benefits that hydro, gas and coal have provided, essentially for free, to keep the electricity system secure have been taken for granted.
“As more intermittent generation comes into the grid, new markets are going to have be created for things like inertia, which are essential to energy security.”
Opposition energy spokesman Mark Butler would not comment.
The commission is working to address immediate concerns in relation to emergency protection, particularly relating to South Australia’s current frequency issues, as well as new mechanisms to allow security to be maintained across the entire system.
South Australian Energy Minister Tom Koutsantonis said there was an urgent need for a national policy that integrated renewables into the national energy market.
“The current lack of federal leadership on this issue is seeing coal-fired power stations exit the market in an unplanned way with no investment in generation to replace that which is lost,” he said.
“The most efficient way to create a market incentive for more base-load generation is through an emissions intensity scheme — a base line and credit scheme which forces dirty generators to pay cleaner generators to operate in the market.”
AEMO blames SA wind farms: ‘We don’t know what they are not telling us’
12 December 2016
The Australian Energy Market Operator has reprimanded wind farm operators in South Australia for not informing the regulator about the safety settings on their turbines, which led to blackouts in September.
While AEMO has been criticised about its role in the lead-up to the September 28 outage, chairman Tony Marxsen said the obligation was on wind farm owners to inform the regulator about the settings of their turbines and how they deal with adverse events.
“We are facing a bit of a challenge here in that we don’t know what to ask if we don’t know what they are not telling us,” Dr Marxsen said in an interview with The Australian Financial Review.
“They have an obligation under the rules to provide that information. We have reviewed all the information provided and found no information about this particular feature of the turbine controls.
“The rules are very clear. They state that the proponent for connection has to provide models that fully represent the behaviour of their equipment under conditions of grid disturbance. In this particular circumstance, the models that were produced did not. We will be looking at this further in the March 2017 report.”
AEMO’s latest report to be released on Monday has made 15 recommendations to deal with future events and to reduce the risk of “islanding” SA, which has cost business millions of dollars in lost revenue.
The AEMO report confirmed earlier reports that the state-wide blackout in SA was caused by wind farms reducing their output after storms knocked down three transmission towers in the state’s north.
Within the space of seven seconds, 456 megawatts of output from nine wind farms north of Adelaide was taken out of the grid, which cause a surge of power through the Heywood connector to Victoria. The state’s electricity grid essentially “tripped”, causing it to be cut off from the rest of the NEM to protect it from other states.
AEMO said the influx of wind and solar projects in SA, which now account for about 40 per cent of the state’s output, as well as the removal of the more reliable synchronous generation like coal and gas had put unprecedented strain on the NEM.
“The significance of the event and the intensity of review has brought to the fore a range of broader issues associated with the changing generation mix across the NEM,” it said.
“The generation mix now includes more non-synchronous and inverter-connected plant, which has different characteristics to conventional plant and uses active control systems to ride through disturbances.”
But in a startling admission, AEMO said it was not even aware the wind turbines, which it approved to provide power into the NEM, had the safety features that caused them to scale back generation capacity.
“AEMO was not aware that some wind farms may not be capable of riding through multiple successive faults on the network,” it said. “AEMO was not aware of the protective feature of these generating units that caused these power reductions and has taken action to ensure the limitations are known and appropriately managed.”
The 15 preliminary recommendations cover AEMO being better prepared before extreme weather events, a stronger system protection scheme to minimise regional separation from the grid, quicker restoration following a “black system” and limiting the time of a market suspension after an event.
Dr Marxsen will use his speech in Melbourne to say the regulator was not singling out renewables saying previous supply disruptions in SA in 1999, 2004 and 2005 were caused by coal and gas-fired power stations.
“September was a truly technology-neutral blackout,” he will say in his speech.
But critics of SA’s headlong dive into renewables will use the AEMO report to push for a more balanced approach to the future of the NEM, warning there could be more blackouts if coal and gas were phased out of the grid too quickly.
The Financial Review
The AEMO’s Tony Marxsen’s claim that “previous supply disruptions in SA in 1999, 2004 and 2005 were caused by coal and gas-fired power stations” is utter bunkum. On none of those occasions did a power generator disappear without warning or notice: peak loads may be unable to be met on days of extreme heat in Australia, leading to load shedding, but thousands of MWs of conventionally generated power doesn’t just vanish like wind power does.
Marxsen continues to demonstrate a level of knowledge that must fill Australian power consumers with supreme confidence in his ability to arrest Australia’s unfolding wind power disaster, when he admits that the AEMO’s knowledge of how wind turbines operate is limited to what their operators tell the AEMO. But his line that “September was a truly technology-neutral blackout,” is simply astonishing.
One might reasonably have expected the AEMO and Marxsen to have caught up with the relatively recent invention of the Internet and the Google search?
It took STT all of two clicks to find what Siemens says on its website about the automatic shutdown of wind turbines when wind speeds hit 25m/s (90km/h):
Nature presents us with different kinds of challenges. High wind can create extremely high loads, and as a result wind turbines are normally programmed to shut down if the 10-minute mean wind speed exceeds 25 m/s. This may pose a significant challenge for the grid system – for example, if turbines in large wind farms shut down simultaneously.
It was precisely that feature that saw wind power output collapse on 28 September this year, as wind speeds reached gale force across the State.
The AFR reckons that critics of South Australia’s wind rush are warning that SA will suffer routine load shedding and more statewide blackouts. These aren’t warnings, these are facts being dished up to South Australians on a daily basis.
The mass blackout on 1 November last year:
And the 1 December blackout:
All had one thing in common: a precipitous collapse in wind power output.
That data, too, is collected from the AEMO and helpfully compiled by the boys at Aneroid Energy. For anyone with a passing interest in South Australia’s current wind power calamity, a few clicks is all it takes to get behind wind industry spin and political obfuscation.
For someone charged with responsibility for Australia’s power supply it should be essential reading. Oh, and facts like the automatic shut down of wind turbines at wind speeds greater than 25m/s are out there too. All it takes is a modicum of interest and an internet connection. Something the AEMO seems to clearly struggle with. At a time when South Australia’s grid is on the brink of collapse, AEMO ignorance can hardly amount to any kind of bliss.