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What is Frequency Control?

Power plants and transmission network lines suddenly fail from time to time. When they do, it impacts the grid’s frequency, and the system needs resources that can respond quickly to prevent cascading power failures. Enel X led the charge in opening up the frequency control markets to demand-side energy users in 2017, and again in October 2023 when a new, “Very fast” frequency control market was launched. Enel X is now the largest C&I player in the frequency markets.

How does it work?


Grid need

The Australian Energy Market Operator (AEMO) balances the supply and demand of electricity in real-time. When the grid’s frequency deviates, AEMO calls on Virtual Power Plant & Demand Response aggregators indicating that there is an urgent need for dispatchable capacity to support the system.

Frequency control services are procured in the Frequency Control Ancillary Services (FCAS) market and prices are determined every 5 minutes based on the real-time balance of supply and demand in the market.  You receive the highest-priced offer that successfully cleared in each 5-minute interval, and earn revenue for each megawatt your site is available for, even if your services aren’t needed for that interval. 

VPP is called

Enel X’s Virtual Power Plant (VPP) is called on, who aggregates its customer’s energy load or distributed energy assets made up of onsite equipment, backup generation assets, and battery energy storage solutions across businesses in Australia. Enel X offers its portfolio’s capacity to AEMO as a new source of power supply during these critical times.

Customer responds

Customers either switch to backup power sources (BESS, backup generation) or reduce or modify energy usage when called on. This makes their power flexibility available to AEMO, and we are able to automate the process our customers.

There are four frequency control services businesses can provide (Very Fast, Fast, Slow, Delayed), and each offers different revenue earning potential. Based on your technical capability, we confirm which categories you can participate in.

  • We can adjust your level of participation at any time, and you can opt out if needed for operational reasons
  • The revenue earned from your participation is proportional to the average kW you offer
  • The revenue you can earn will be highest if you can provide all four services, including the Very Fast frequency control service, which requires your equipment to respond in less than one second
  • An FCAS event last up to 10 minutes

Earn regular payments

Businesses enrolled in our VPP are paid to respond automatically to deviations in the grid’s frequency to help to restore it to its normal operating range. 

Advance Australia’s renewable future

DR allows independent aggregators like Enel X to provide additional, dispatchable capacity to support the grid. This new capacity is essential to supporting the renewable energy transition, because dispatchable resources help to integrate variable renewable energy sources onto the grid.
Backup generator

Leading the charge with DR

We’ve had a long history working in Demand Response and frequency control services. We entered New Zealand’s Instantaneous Reserves market in 2008, their equivalent to the FCAS markets. Today, we’re one of the biggest market participants, representing on average 65% of the interruptible load in the market. Our experience and expertise offshore enabled us to become the first third-party aggregator in the NEM in 2017. Our VPP has grown rapidly, and is now the largest C&I supplier in the FCAS contingency raise markets.

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Last summer saw unprecedented network conditions across the NEM with bushfires and extreme weather events. With Enel X we provided instant capacity to support the grid’s frequency throughout. Our battery responds in less than 1 second, making it an ideal technology for participation in FCAS to support the grid.

Andrew Wilson, Energy and Sustainability Manager

University of Queensland

Contact an Enel X team member to learn more about our products and services.