| Grid stability and renewables integration


System load (MW)


2500


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2024: Forecast 2025: Forecast


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Potential for grid instability


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Abundant solar during the day means the bulk of the electricity in the Perth region is provided by PV. However, the mornings and late afternoons see a switch to conventional power sources. Source: Synergy


renewable electricity and storage infrastructure to support increased demand over the next 20 years. Wind, solar and battery energy storage systems, however, won’t be enough to fulfil expected demand if coal is to be phased out simultaneously. Hence, investment in natural gas infrastructure continues. Current planning anticipates that additional gas generation will be required to provide firming to the energy system. Accordingly, existing gas plants will benefit from a 10-year exemption from new emission thresholds. Australian federal and state governments have shifted policy in recent years to make life less difficult for gas plants. This originated from the realisation that they are required to maintain reliability. Thus, efforts are underway to entice gas plant owners to not prematurely exit the market for commercial reasons or due to regulatory pressure. “Risks to the transition are emerging and must be carefully managed,” said Westerman.


Low load challenges


With the Perth metro area being dominated by rooftop solar, low load periods have become a real issue. Demand for grid electricity drops dramatically as the sun moves higher in the sky. With so many peaks and troughs in grid demand, maintaining a stable and reliable electricity supply and avoiding blackouts is a concern. As in other duck curve regions like California, peak usage periods occur in the early morning and late afternoon/evening when solar isn’t


available in sufficient quantity. The WA power system needs its existing coal and gas fired generators to be available at these times to provide a steady and reliable flow of electricity. Synergy and other utilities are campaigning for people to shift as much energy consumption to the middle of the day to use up available solar energy and lower demand during peak periods. Synergy is also operating virtual power plants (VPPs) that can better adjust and respond to the needs of the electricity system. As part of this, rooftop solar and other distributed energy resources (DERs) are being incorporated into the power system in various ways.


Emergency Solar Management (ESM) is one example. It seeks to add stability when there is a large amount of solar power being generated from rooftop solar systems, and not enough grid demand. At such times, remote management of household solar is needed to prevent potential outages. For a few hours, a Synergy customer’s solar can be remotely turned off, and then on again when the emergency is over. These measures certainly help. But they are not enough to keep the grid stable. What has been realised is the critical role played by rotating assets such as steam turbines and gas turbines in adding inertia, stability, and support to the grid.


Pinjar power station


The policy position in WA is to continue to add renewable resources at a high pace, accelerate transmission network improvements, and


phase out coal while encouraging investment in improvements to existing natural gas facilities as the best way to manage the energy transition. The Pinjar power station near Perth is one example. It provides peaking power when needed as well as grid stability. Located approximately 50 km north of Perth, it consists of nine GE Vernova gas turbines – six Frame 6s and three Frame 9s. They are mainly called upon during hot summer days, in emergencies, and at times in response to the morning/late afternoon duck curve pattern. The plant has a capacity of 576 MW. It is operated by Synergy. The turbines can be online and available to the grid within 15 minutes when requested.


In addition to peaking power, several of the units are equipped with synchronous self shifting clutches from SSS Gears Ltd of Sunbury, UK, to provide system stability and grid support. These clutches are designed so that when the turbine is moving faster than the generator, the clutch automatically is engaged, and the turbine drives the generator. Once the generator is synchronised to the grid, the turbine slows down and the clutch automatically disconnects from the generator, turning it into a synchronous condenser. These SSS clutches are incorporated into the load gears made by Flender-Graffenstaden of Strasbourg, France. This synchronous condensing upgrade provides a number of benefits to the grid.


Reactive power provided by a synchronous condenser offers voltage stability. While real


www.modernpowersystems.com | April 2025 | 15


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