Here in Renewables-World downunder, most people don’t know the grid has barely scraped through the last two weeks. We almost lost an Aluminium smelter, came close to a statewide blackout and South Australia is (possibly) still islanded from the rest of the National Grid.
The AEMO held a crisis meeting yesterday but this trouble started Friday week ago in what was described as a “white knuckle event” by energy analyst, Paul McArdle at WattClarity. A storm knocked down six large transmission towers on the high voltage interconnector line in Western Victoria which left South Australia suddenly islanded. This time SA had 1,000MW more energy than it could use, so frequency in SA suddenly rose to a near disastrous 50.96Hz and briefly perhaps even higher. (Wait for the official reports). The system teetered but managed to stay running. Prices rocketed up to the usual spike to $14,500/MWh in both Victoria and South Australia.
It would have been nerve-wracking in the control rooms. The Portland Aluminium Smelter in Victoria, which is the largest single user of electricity in Victoria, had a near death experience. Both pot lines shut down immediately. It appears emergency workers only managed to get 50% of the power back up 3 hours and ten minutes later. The future of the plant hung in the balance — after a few hours without power pot lines can freeze permanently solid. It’s referred to as a “near fatal event”. If those 1,000°C pot lines cool to 700°C the molten aluminium sets solid and that’s the end of the plant.
The smelter is on the SA side of the broken transmission line, so it’s now a part of the extended South Australian network. Though it is largely powered by Mortlake Gas generator — which is also in Victoria, but on the western side of the break.
SA is effectively still islanded without the main interconnector. The only line in or out is the small 300MW direct current”MurrayLink” line, which has been constrained to zero (meaning, left unused, ready for an emergency.)
UPDATE: Remember a DC or direct current line is not able to help with frequency much — it can’t do “FCAS” except in an indirect way to help match generation and load a bit better. Obviously DC power doesn’t run at 50Hz or any Hz or it would be AC.
It presents itself with a situation almost unique in the world – a state grid that is normally powered more than 50 per cent by renewables operating without any major links to another grid. — Giles Parkinson, Reneweconomy
The AEMO has scrambled to keep the system running. Because it has no control over rooftop solar power, the agency is instead comandeering the three batteries, and telling 23 different wind, solar and gas generators that they will be constrained to zero output if South Australia’s minimum demand falls below 800MW.
In this situation, it is causing a headache for the grid operator, and it underlines why AEMO has been pushing for new measures and mechanisms that allows it to have some sort of control over the output of rooftop solar, now totalling more than 10GW in Australia on more than 2.2 million rooftops.
LATE NOTE: Rooftop solar doesn’t help with FCAS either. Another reason the AEMO would be concerned about it dominating the lunchtime slot.
Markets go haywire
Prices in SA have been zero or slightly negative in SA — there are just too many generators there. But what there isn’t is much stability — there are few big turbines. So the gas generators have been reaping in the maximum FCAS (Frequency Control Ancilliary Service) fees.
The share of renewables in the state’s grid has averaged 50 per cent since it became an energy “island”, with rooftop solar providing much of daytime demand, and wind energy playing its role at night time. Prices have been volatile, it’s been negative more than positive.
That has created more problems, however. AEMO has had to intervene to prevent an “excess of negative pricing residues” flowing between South Australia and Victoria, and causing price settlement issues in both states. It has also had to impose a price limit on the frequency and ancillary services market, after the various FCAS markets pushed the price to the market cap for several days running.
This is the result of the few gas generators capable of delivering FCAS in South Australia having no competition from interstate, due to the failed Heywood interconnector, and the lack of competition from local batteries otherwise seconded by AEMO.
— Giles Parkinson, Reneweconomy
Commenters at Reneweconomy are cheering at the thought of lots of renewables and cheap electricity. But they don’t seem to realize that investors might not be as enthusiastic.
Bidding games?
For the next day or so the national system balanced on the brink. Paul McArdle described his bafflement at some of the sudden volatility. Far away in NSW an LOR 2 situation (that’s a Lack of Reserve) suddenly appeared on Saturday at 5pm without warning, out of nowhere. The margins were extremely tight. The whole state of NSW had a bare 350MW of extra capacity ready to go in a system that was generating 12,000 MW. Apparently in toto with imports NSW was using 13,717MW at 16:55. This is close to an all time high.
McArdle goes on to point out that the sudden loss of capacity was coincident with some very tricky bidding by Colongra Gas Turbines (Snowy Hydro) which suddenly withdrew capacity and then offered it back 28 minutes later after the LOR2 was called. They essentially invited the AEMO to direct them on, he says. Too tricky by half. Were they gaming the system to ensure compensation?
McArdle says he “can imagine that others would use a few different adjectives in relating their own perceptions of this sort of process, and participant behaviour.”
There could be some unintended consequences in fake markets where customers don’t get to choose the cheapest energy unless the wind isn’t blowing.
h/t Dave B, Robber, Tonyfromoz, Robert Rosica