By Phil Kreveld
Could Australia’s grid suffer the same fate that Spain’s recently did? Of course. In fact, we might even be in a more perilous situation. The Iberian grid crash on April 28, affecting Spain, Portugal and Morocco, whatever intricate details might be still revealed, resulted from an unhappy marriage between a traditional partner, old-fashioned synchronous generation, and a new-age renewables bride. And, we here, also have taken our eye off the ‘difficult relationship’ happening under our noses.
How so, this inharmonious union? Marriage counselling would reveal the dangers for rupture through incompatibilities. One way out is to decide that we should never ever abandon the synchronous groom—and to hell with the asynchronous bride. Practicalities show this to be stupid, because irrespective of boring climate change arguments, the money is on asynchronous renewables. Far better, therefore, to concentrate on how to make the union work so as to minimise the occurrence of blackouts.
Related article: Reactive power, voltage regulation, and other lessons from Spain’s grid failure
In 1965 North America experienced its worst blackout when 30 million people lost power in the north-eastern United States and south-eastern Ontario, Canada—and there were only traditional synchronous generators in operation then, likewise Italy in 2003, and Türkiye in 2015, just to pick out a few. Large electrical power systems experience frequency and voltage instabilities, and oscillations that can cause blackouts and enormous damage to electrical machines. Operators of large grids had more or less worked out operational procedures to minimise the chances of disruption—and then renewables came along. Welcome to a new ballgame.
We are in a more dangerous situation than Spain. It’s the millions of ‘ma and pa’ rooftop solar installations that can account for over 50% of power demand. These are an unruly breed. Hence measures like ‘Emergency Backstop’ to turn off solar inverters when there are ‘instabilities’ in the transmission grid. In Spain, inverters (the larger ones) are likely to have been responsible for exacerbating voltage instability, a major factor in the blackout. In Australia, the Australian Energy market Operator, has (a) asked a number of batteries connected to the transmission grid to be in a discharged state at daybreak, and (b) mandated Emergency Backstop (switching off solar inverters) in order to have sufficient power flowing through transmission grids—to prevent voltage instability.
The Spanish veto on inverters to supply reactive power voltage support, shoved the responsibility onto a number of synchronous generators to contain voltage rise on unloaded high voltage transmission lines. It turns out that prices for electricity where between low and negative, prior to the midday blackout Nevertheless by government direction during hours of low demand a number of synchronous machines must stay connected to provide voltage support. About 12GW of capacity was not available because of maintenance procedures and breakdowns. Synchronous generators, under-excited so as to absorb reactive power on lightly loaded transmission lines are a recipe for voltage angle instability.
Related article: Milliseconds for decisions—or is it hasta la vista?
For sure, more analysis on the April 28 event will emerge. Meanwhile, state energy ministers are becoming nervous—and not a moment too soon. Without necessarily understanding the electrical intricacies, a sense of misplaced faith in the growth of renewables making up for the decline in gas and coal-fired synchronous generation is dampening enthusiasm. The uncertainty which is seeing recourse to consultations (kept out of the news) will not make up for the lack of a national grid engineering plan. Such a plan, were it in place, would take into account active and reactive power limits for renewable energy zones to fit in with transmission line impedance parameters. It would specify where voltage compensation substations would be located, and whether var, statcom, or synchronous condensers, taking into account delivery schedules to keep pace with the growth in renewable capacity. It would engineer restart procedures for distribution networks and release the Australian Energy Regulator handbrake on necessary investment.
That’s not the end of it because stability including voltage angle and synchronising torque, damping of power oscillations—all vital in maintaining grid viability can only be assured by a whole-of-system design regimen. Instead, we are using ‘suck it and see’. That’s why we will, sooner or later, have major breakdowns—and it’s guaranteed that the blame will be go to wind, solar, batteries, and to their proponents, when it is really due to piecemeal, economics-based solutions, mucking around with ministerial meetings, and a willful blindness to the cost of grid failure to the national economy and wellbeing of the citizens.
