The AEMC today proposed significant changes to technical performance standards for generators seeking to connect to the national electricity grid, and the process for negotiating those standards.
Generators play an important role in helping AEMO and network businesses keep the lights on. This can include having the technical capability to control their voltage and frequency, and the ability to stay connected even when there is a major disturbance to the power system.
AEMC Chairman, Mr John Pierce AO, said today’s draft rules provide a foundation for a secure, least cost transition as new generators with different technical characteristics join the power system.
“The electricity system is transitioning, with a large number of new generators like wind and solar farms set to connect in coming years.
“We want to get the balance right between cost and system security for consumers.
“Matching technical requirements to local power system needs is key to keeping costs down for consumers," said Mr Pierce.
This major piece of work is the result of a rule change request from AEMO and months of cross-industry collaboration.
A team of technical experts comprising AEMO, generators, network businesses and power systems engineers worked with the AEMC throughout the project to systematically review each technical standard. This targeted approach will enable the standards to be negotiated for each connection – tailored to circumstances.
“For example, if provision of voltage control isn’t an issue in a particular area because there are plenty of generators providing this capability already, we don’t want to be forcing new generators connecting to the grid in that part of the system to have to pay for unnecessary voltage control capability,” said Mr Pierce.
The draft rule tightens some standards where needed and sets clearer roles and responsibilities so all parties – generators, networks and AEMO – know what they have to do when negotiating the required standards for a particular location.
The AEMC proposes a transition period of eight weeks after the final rule is made to give everyone time to adjust, before the new performance standards apply.
Submissions on the draft rule are due by 13 July 2018.
This rule change request addresses a recommendation made in the Finkel review to update generator connection standards in the National Electricity Rules. It is also part of the AEMC’s security and reliability action plan to provide AEMO with the tools it needs to manage a power system with a growing share of renewables and other forms of capacity.
This includes new rules starting in July 2018 to make networks maintain minimum levels of system strength and inertia.
Media: Bronwyn Rosser, Communication Specialist, 0423 280 341; firstname.lastname@example.org
EXPLAINER OF TECHNICAL TERMS
How are reliability and security managed in the national electricity market?
To keep the lights on, the power system needs to be:
- secure – able to operate within defined technical limits, even if there is an incident such as the loss of a major transmission line or large generator
- reliable - have enough generation capacity, network capacity and demand response to supply customers.
The Australian Energy Market Operator (AEMO) is responsible for operating the power system in a secure and reliable state in accordance with standards and guidelines, including those set by the AEMC’s Reliability Panel.
What is a secure power system?
The power system is in a secure and safe operating state if it is capable of withstanding the failure of a single network element or generating unit.
Security events are caused by sudden equipment failure (often associated with extreme weather or bushfires) that results in the system operating outside of defined technical limits, such as voltage and frequency.
What is a reliable power system?
A reliable power system has sufficient generation and network capacity to meet the consumer load in that region.
Reliability events are caused by insufficient generation or network capacity to meet consumer load.
Reliability events due to insufficient generation and interconnector capacity are usually predicted ahead of time by supply and demand forecasting. The associated consumer load shedding may be shared across parts of the national electricity market.
What is power system inertia?
The ability of the system to resist changes in frequency is determined by the inertia of the power system. Inertia is provided as a consequence of having spinning generators, motors and other devices that are synchronised to the frequency of the system. Historically, in the national electricity market, plentiful inertia has been provided by synchronous generators, such as coal and gas-fired power stations and hydro plant.
However, some new generation technologies, such as wind turbines and solar photo-voltaic panels, are not synchronised to the grid and have low or no physical inertia, and are therefore currently limited in their ability to dampen rapid changes in frequency.
What is system strength?
Non-synchronous generators do not contribute to system strength as much as synchronous generating units. System strength is a measure of the current that would flow into a fault at a given point in the power system.
Reduced system strength in certain areas of the network may mean that generators are no longer able to meet technical standards and may be unable to remain connected to the power system at certain times.