By Phil Kreveld
The renewable transition is no longer about saving the planet—it is, in essence, the modern technology for generating electrical energy.
A national asset being splintered? Yes, it’s the Australian electricity system.
A very recent afternoon political briefing on the national television broadcaster featured an interview with an opposition front bencher. It brought forth a statement on the transition to renewables along the lines of baseload being necessary and that it would need to include coal-fired generation.
Renewables were propelling us to an uncertain economy, according to the interviewee. The government is having a field day with the opposition, allowing a private member’s bill on dropping net zero targets to be debated daily. Embarrassing the opposition appears much like shooting fish in a barrel, but adds nothing to a much-needed analysis of the transition locus.
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It is regrettable that neither side in the parliament seems to appreciate the gravity of the renewable transition including product delivery delays and engineering challenges posed by networks incorporating batteries, and solar and wind generation. Sundering the national electricity system will happen because of having a bet each way on synchronous and asynchronous technologies.
The atavistic reference to synchronous baseload is a distraction—the concept, no longer reflecting the reality of modern grids in many developed countries. Dynamic grids with power flowing reversibly are the new reality—and Australia is leading the pack in highly variable power flows.
Escaping the new age ‘transitionists’ and the ‘traditionalists’ is a reality, no longer novel! High-capacity inverters for solar are built faster than turbine-generator sets, and that is without having reckoned on long construction times for steam-raising plant. Land-based Type III and IV wind generators being a shared technology of electrical machines and power electronics, and needing considerable civil engineering, have longer supply times.
Wind generation being a major part of European requirements, puts Australia at the back of the queue. Marine installations are a different kettle of fish, involving big port infrastructure. Battery energy storage systems are somewhere in between solar and land-based wind. We lack the expertise for coal-fired steam raising plant construction—i.e., pointing at China’s construction rate is of no relevance for us.
Net zero targets are important but we are well-served by not being dogmatic about target dates because making asynchronous sources in dynamic networks work reliably is a new science. Its voltage, frequency and power oscillation intricacies are being solved and we can have confidence that a secure and stable system will evolve—at some stage.
However, we appear to lack the confidence of our ‘renewable’ conviction, and rather than addressing the technology supply lines and engineering challenges for the south-eastern grid, in particular, the national preference is to prolong the ‘climate wars’ by proposing rather arbitrary rules regarding acceptable and non-acceptable means of generation. The renewable transition is no longer about saving the planet, although so proclaimed the midwives present at its nascence. It is in essence, a modern technology for generating electrical energy.
Demystifying the engineering aspects of the transition is straightforward. Asynchronous generation either requires a stable voltage source or be capable of forming voltage. Most of the renewable sources require the former, and are technically electrical current sources. We still rely on synchronous generation to provide a stable voltage.
There are a small number of voltage-forming inverters associated with large battery systems. They are, in principle, equipped to take over from synchronous generation. The relatively new Collie battery system, 200km south of Perth, is voltage forming. The transmission line connecting it to Perth’s roof top solar inverters is essential in keeping them operating as these are current sources only.
The Collie battery-inverter system solves what was an embarrassing situation where consumers were requested to keep air conditioners running to prevent energy export into the transmission system. Now, with the Collie facility at the far end of the line, stable voltage is there for Perth’s solar inverters, while Collie’s battery is being charged by their aggregate export of excess energy.
The Collie inverter is bi-directional, and capable of operating with charging or discharging current, the latter needed in the evening. The voltage support is always present via reactive power support from the Collie voltage-forming inverter. The enormous advantage of Collie and like installations, is this bi-directional feature. Synchronous generators can only supply power, and at best absorb some reactive power but at risk of becoming unstable through under-excitation.
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The Callide C mishap in 2021 happened because power was flowing into the generator. The relay monitoring for reverse current failed, thus not opening the circuit breaker protecting the generator. Power electronics is far more forgiving.
It is high time for a rational, engineering-driven approach as the driving force in the adaptation of solar, wind and batteries. Ideology and even climate change arguments should be cast aside—they will not help in maintaining security and stability in the national electricity WEM and NEM systems.
Furthermore, the dynamic nature of distribution networks is staring us in the face—and nothing but protective business practices are stopping its utilisation to reduce the need for added transmission capacity. And as to the politics—it might serve as entertainment.
