A new report by a national electricity regulator has found that, as occurred during September’s statewide blackout in South Australia, renewable power sources cannot cope with rapid or large changes in frequency, leading ultimately to a “black system”.
The Australian Energy Market Commission today released its interim report on its review of power system security in the national electricity market.
The report found the nation’s power system is secure when voltage and frequency are maintained within defined limits, which is achieved 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 warned.
Spinning generators, motors and other devices synchronised to the frequency of the electricity system have naturally provided the inertia necessary to allow the system to cope with uncontrolled changes in frequency.
But new technologies such as a wind or solar have no or low inertia. Currently they 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,” AEMC chairman John Pierce said.
AEMC is currently working on five rule change requests to address both 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.
Despite numerous warnings to the South Australian Labor government about the risk of frequency problems and increased load shedding, brownouts and blackouts, the state has pursued a renewable energy policy that has seen around 45 per cent of its generation come from wind and solar.
The state’s last coal-fired baseload power station was forced to shut in May because of the rise of renewables, with Premier Jay Weatherill and his Energy Minister Tom Koutsantonis both declaring “coal is dead”. The state is now reliant upon an interconnector with Victoria to import coal-fired baseload power.
It has today emerged that a plan by the owners of the Northern power station and transmission company ElectraNet to reopen the power plant as a converter to stabilise the state’s wind-vulnerable grid was abandoned because of the red tape involved.
The power station would be demolished within one to two months but it would have taken at least a year for a full study and assessment on the reopening proposal under government regulation, before a decision could be made on funding.
While there has been no cost estimate released, such a move would likely be very expensive.
ElectraNet is urgently looking at options to stabilise the state’s grid in the absence of the Northern power station.
Mr Pierce said there were challenges ahead in managing system security, which was essential to allow reliable electricity supplies to be provided to customers.
“The changes that need to be made centre on the physics of energy supply, transmission and meeting demand,” Mr Pierce said.
“Many different technical options are emerging in today’s electricity sector and we want to encourage further innovation – rewarding the best options that may mature over time.
“We also need market mechanisms that reward the best outcomes while keeping consumer prices as low as possible over the long term.”
The AEMC interim report suggests changes that include new measures to enable provision of additional inertia for the system most likely through synchronous machines and development of fast acting frequency response services, which might be provided via invertor-based generators such as wind turbines, by energy storage devices and by demand-response schemes.
“This review puts an umbrella over many issues being raised by stakeholders in relation to the power system’s ability to keep the lights on while maintaining its frequency at a constant level,” Mr Pierce said.
“The review will consider both policy mechanisms that are in place now; and analyse how any of the feasible emissions reduction policies may impact the future power system.”
He also said that a more efficient gas market would improve the power system’s ability to integrate renewables like wind and solar by providing fast-start backup for intermittent generation.
“Making it easier to buy and sell gas helps lower supply costs for gas-fired power stations which are now replacing coal generators,” he said.
Energy Minister Josh Frydenberg said the Turnbull government welcomed the draft AEMC report.
“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,” Mr Frydenberg said.
“As Bill Shorten and his mates in the Labor states chase 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 secruity across the National Electricity Market.
“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.”
He said these issues will be considered by the Finkel Review and the AEMC.
South Australian Energy Minister Tom Koutsantonis said there is an “urgent need for national policy reform that better integrates 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 told The Australian.
“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.
“There are numerous reports from the nation’s best minds sitting on the Prime Minister’s desk recommending an EIS as a way of better integrating renewables into the market and provide more system security”
The AEMC is calling submissions by February 9.