By Phil Kreveld
Making predictions is a mug’s game, yet irresistible. There are a sufficient number of cooks stirring the renewables broth to make its outcome unpredictable! Yet listening to presentations at the recent Australian Energy Week in June, you could be forgiven for vesting quiet confidence that all is in hand. But it’s far from being the case.
We delve into some technologies which could indicate future directions, and with implications for energy markets. The integrated systems plan of the Australian Energy Market Operator is based on pumping sunshine and wind. Commodities obtainable without labour, and which are pegged to coal and gas prices to maximise profits. Coal is a fast-diminishing presence according to the Australian Energy Market Operator’s integrated systems plan.
Dr Tim Nelson’s Electricity Services Entry Mechanism implies generated power as the metric being based on capacity but is actually structured on energy income, in particular regarding firming. Transmission networks are making investments based on power—or more accurately, on voltage controls based on variable power flow. And as is already apparent, the Australian Energy Market Commission, is considering higher network charges for electrical energy consumers.
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Conventional network engineering confines the scope of rooftop solar
As with so many endeavours, resistance to change stymies fresh approaches in favour of twisting established practices to try to meet new goals. Distribution networks are an example. Nearly all generated energy satisfies the energy demand of residential consumers, commerce and industry.
Distribution of electrical energy is a monopolistic business that has given rise to ‘ring fencing’ so that consumers would be free to contract for energy with many suppliers. But the world as envisaged in 1994, the one with ‘Power of Choice’ regulation no longer exists. Consumers of electrical energy have installed their own’ power plant’ to render themselves close to independent from large scale generation. This leads to curtailment of large-scale generation, and highly variable power flow in transmission lines.
The relative independence mentioned above is causing major engineering investment in transmission line augmentation (var compensators, synchronous condensers, experimentation with power flow regulators) to counteract the diurnal and rapid daytime power changes due to rooftop solar. Within distribution networks, the extensive capital expenditure required to deal with reverse power flow (new transformers, re-conductoring, on-load tap changers re-engineering, phase balancing and voltage compensation) is being avoided by dynamic operating envelopes (DOE) and the common smart inverter protocol (CSIP-Aust incorporating TS 5573:2025), originated in South Australia and is based on the IEEE 2030.5 communication protocol. CSIP-Aust is not a requirement for solar inverters under AS/NZS 4777.2, but highly desirable for the operation of DOE. However, the bulk of rooftop installations do not meet the CISP-Aust capability but new installations must comply after October, this year.
All these measures are part of an unwillingness to recognise that the electrical energy world has changed—democratisation of energy is now a reality. Instead, we are shoehorning 21st century technology into the 19th century world of Charles Prometheus Steinmetz, the American father of alternating current power distribution and transmission. However we are leaders in rooftop solar and thus, our clash of old and new technologies is the subject of studies by other countries.
Electric vehicle engineering to the rescue
The new energy paradigms are mainly hidden from public discussion, for example the cooperation between the CSIRO and Tapestry, a part of Google’s Moonshot operation. There are two salient features, one being GPS-based network monitoring, and the other an adaption of inverter technology commonly used in electric vehicles, utilising SiC switching elements for inverter-converter operation. Dr Saul Griffith is informally associated with CSIRO’s Research efforts, and he brought the writer’s attention to these important research elements at the recent Sustainability Conference held at the Melbourne Convention Centre in early June.
Electric vehicle inverters supply variable frequency power to wheel motors, and switch to rectifier operation during dynamic braking. The wheel motors become generators and consequently AC peak voltage rises above that of vehicle battery voltage. By changing the switching timing of the SiC switches by 90 degrees from zero crossover of voltage, the vehicle inverter reverses current flow and charges the battery.
This technology can be fruitfully applied to distribution networks by utilising ‘dual function’ inverter-battery energy storage systems, with typical ratings of 300kW. The dual function inverters can be inserted in low and medium voltage buses to support the ‘dumb’ voltage-following household, commercial and industrial solar inverters. These can cause grid instability, for example during strong reverse power flow when, because of network impedance interacting with Thévenin-equivalent impedance of inverters, power oscillations occur. This would be avoided by the smart inverters changing to rectification and absorbing excess power flow in their batteries.
GPS monitoring for near-instantaneous decision making
Utilising point of wave monitoring and GPS, distribution networks can be turned into microgrids if required, with voltage and frequency measurements on both sides of static transfer switches permitting re-synchronisation to sub-transmission. Also, the same combination of technologies would facilitate black-start being initiated by distribution networks. There are lots of ‘buts’ to this, in particular cyber security, thus necessitating ‘dead man’ re-synchronisation via protective relays.
Nevertheless, the above-described technologies could liberate increasingly energy-independent distribution networks from 100% dependency on external generation and transmission which increasingly are only functional in supplying constant voltage and frequency rather than power transmission. Furthermore, they would be complementary to dynamic operating envelopes and virtual power plant operations—a plus-plus!
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An impediment—the electrical establishment’s boat anchor
Fact is, however, that new ways of network operation clash with the juggernaut of well-established commercial interests—the very ones making out the bulk of plenary session presentations at the recently concluded Australian Energy Week conference. It’s massive new renewable energy zones, stringing more high voltage transmission, in effect, constraining the final customer from taking charge of their own business.
Making predictions is a mug’s game as mentioned at the outset, but there are a number of factors in play that point to an outcome suiting the major investors, in generation and transmission. The former is looking for safety nets with the proposed ESEM mechanism providing more breathing room to finance investments. The latter has the security of the regulated asset base and Australian Energy Regulator-authorised recovery of investment costs. AEMO as system operator would rather take the sure for the unsure. This translates to keeping the overall system as close as possible to that of the 20th century.
A legitimate conclusion might well be that virtual power networks give prosumers a piece of the action. That is of course correct but—and it’s the important qualifier: it is way too restrictive and transmission network and REZ expansion ignore the economics provided by new technologies that could see the demise of Steinmetz’s world.
