Wind and solar farms in north west Victoria and south-west New South Wales have been warned that they face up to 100 days or more of zero output over the next year because of the need to upgrade the local transmission and distribution networks.
The warning from the Australian Energy Market Operator will affect wind and solar farms as north as Broken Hill in western NSW, and new and existing projects in central west Victoria. The outages have already begun in some cases.
Most of the affected wind and solar farms are based around the so-called “rhombus of regret”, a rhombus-shaped part of the electricity grid linking Mildura, Horsham, Kerang, Ballarat and Bendigo that is struggling to cope with the increase in renewable energy capacity.
The wind and solar farms affected include the Silverton wind farm at Broken Hill, and the neighbouring Broken Hill solar farm. In Victoria, the recently opened Wemen, Karadoc, Gannawarra and Bannerton solar farms are impacted, and to a lesser degree some older installations such as the Waubra, Crowlands and Kiata wind farms.
The worst affected appear to be the Wemen, Karadoc and Broken Hill solar farms, which have been warned they will be curtailed back to zero output for extended periods, and will be affected by nearly all the work to be undertaken over the next 13 months.
That work will be be undertaken on the various 220kV lines linking Red Cliffs, Horsham, Wemen, Crowlands, and Kerang. The biggest impact will come from updating communication infrastructure, with the wind and solar plants warned of up to 76 outages, each lasting half a day to a full day. The exact timetable has yet to be established, and in any case may change.
Another 24 full-day outages will be required for various line and conductor capacity upgrades, and a few other outages will be scheduled to connect some new wind farms such as Neoen’s Bungala and Tilt’s Murra Warra to the grid. The Murray Link connection to South Australia will also be affected.
AEMO says 480MW of wind and solar has been added to the grid in the last year, and with another 900MW of new generation anticipated over the next six months, this will lead to some 1500 MW of new generation located in a very light transmission network.
As a result, a number of necessary upgrades in the next six months will require about 120 outages. The impact of this is that many generators in the region will be constrained downwards, often to zero, during these outages.
Other facilities may be de-rated to less than 5MW output, to ensure system security during the upgrades. (see below for an example).
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One customer described the situation “as a surprise” but conceded it should not have been because it was in the schedule of network outages produced by Ausnet, which runs the local network.
Among those to be affected will be brewer CUB, which is taking output from the 90MW Karadoc solar farm owned by Bay-Wa as part of its aim to source the equivalent of all its electricity needs from solar.
The 88MW Wemen solar farm, developed by Wirsol, is supplying Simec Energy. The Bannerton solar farm, owned by the Foresight Group from the UK, has a contract to help power the tram network in Melbourne.
“Unfortunately there is little that can be done – the works must take place,” the customer said.
But it adds to the body blows inflicted on wind and solar farms in the area, many of which have been de-rated by the new release of “marginal loss factors”, which governs how much of their output gets credited for payment.
Some of the solar and wind farms – particularly those at Broken Hill – have suffered de-ratings of more than 20 per cent because of the increased congestion on the grid, and the distance from load. Others have suffered de-ratings of more than 10 per cent.
On top of this, and as RenewEconomy reported last year, wind and solar farms in the area have previously been warned of significant curtailment because of the lack of capacity on that part of the grid. This has the potential to impact Victoria’s target of 50 per cent renewables by 2030.
Some projects, like the big Kiamal solar farm, have decided to install synchronous condensers to solve some of their issues.
AEMO, in its explanatory memorandum, says the network outages are required because the nature of the local grid has changed so much in the last few years, with 480MW connected in the area in 2018 alone.“This has substantially changed the short circuit ratio and fault current levels which impact voltage stability behaviour in this region of the network,” it wrote. “The system is vastly different to when a major outage last occurred in the area.”
It says it is looking at options to minimise the disruption, such as organising as much work at night time to avoid disruption to solar farms.
AEMO says the communications infrastructure needs to be replaced because it is currently at capacity. It is proposing, as part of its Integrated System Plan, to further upgrade the network in the area and to add new lines to ease the congestion and unlock some 5,000MW of wind and solar projects in the region seeking a connection to the grid.
