Planning for renewables—falling between the talkfest chairs

Wind farm at sunset with transmission towers in the background (aemo report)
Image: Lucy Nicholson/Reuters

It really is high time for the Commonwealth Government to impose its powers on the tussles over interconnectors, the departure of synchronous generation, and the individual state policies regarding renewables integration, writes Phil Kreveld.

For too long renewable grid development has been the subject of talkfests where various experts who wouldn’t know a volt from an amp have held the floor. Meanwhile AEMO does its best to contain the instabilities of frequency and voltage caused by wind and solar inverters.

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However, in the absence of central planning increasing instabilities will be the result of its ISP through the lack of a nationally adopted system design. AEMO connection approval of wind and solar generation is subject to increasingly tough modelling criteria. But more needs to be done because the grid access criteria, also a source of post-connection additional investment for generator owners, are delaying new projects.

That is evident when one talks to engineers on the ground—those with mortgages and kids at school. It’s this very disjuncture between the talkers and the doers, resulting from the reshaping of electrical energy provision by once state held enterprises to privatised businesses that is a major part of the integration problem. 

Let’s start with distribution networks. Rather than focusing on the their increasing independence during high insolation, only voltage problems are being addressed so as to keep the domestic solar owners happy—high voltage causing anti-islanding of their inverters. AEMO is now examining fast frequency control ancillary services (FFCAS) from domestic solar but they are unable to force dynamic restraint of under frequency load shedding.

The lack of some form of network-intelligent UFLS restraint makes FFCAS of doubtful value. Talk to DNSP engineers and one gets the message of ‘all too much hard work’ getting approvals from management—no obvious economic benefit being cited as the reason. Meanwhile aggregators are getting excited selling FFCAS as all that is needed, if you buy the benefit, is a smart meter in order to participate in the money making scheme. This illustrates in spades the need for a consistent, integrated, ‘top-down’ network design approach, one so lacking in the dangerously politicised energy sector.

The very low demand of distribution networks during high insolation, further exacerbated by commercial solar and wind, is causing AEMO to assess the falling participation of synchronous generation because the lower its participation in overall demand, the more voltage and frequency instability occur.

The lack of an all-encompassing control system will either increase islanding of regions or will see to increasingly tough restrictions on the connection of more renewables. The urgency of the looming control problem is hidden from view by elaborate energy and capacity trading proposals. Yet the only solution for network stability is an engineering one.

AEMO publicly, keeps on assuring that its network modelling and modelling of generators requesting connection is all that is needed but it is not believed by its own technologists. Nothing short of a real-time control system capable of overriding the AEMO dispatch engine is going to maintain stability of networks increasingly populated by inverter based resources (IBR). IBR have millisecond response speed, requiring their control to be based on the same time scale and therefore implying forms of automatic, even AI-based control mechanisms. The fact is that it is all unexplored territory, Australia being the world’s most aggressive adopters of renewables.

The time for the Commonwealth Government to intervene in the mess of disparate silos making up vital electrical energy infrastructure of the nation is overdue. A national electrical system design office whose technical details and costings would be lodged, for example, with the AER would be good start.

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Network augmentation and new network proposals could be judged by the AER against the requirements obtained from the national design office. Although there is much to be fleshed out, an in principle decision for the inception of a national design office is urgently needed to shepherd individual state and territory plans into one, contiguous whole. Letting matters roll on as they are currently will result in expensive band-aid solutions and in inciting political brawls as electrical infrastructure failures keep on occurring.

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