The owners and off-takers of existing and aspiring wind and solar projects in a key part of the national grid straddling Victoria and NSW have been warned of “material” constraints to their output because of grid congestion in the area.
The Australian Energy Market Operator says the West Murray Zone (WMZ) in north-west Victoria and south-west NSW (see map below) is now effectively full because of the lack of transmission infrastructure, and new projects face delays in connection and commissioning.
The West Murray Zone – part of which has been dubbed the “rhombus of regret” in reference to the shape of its network – has emerged as a major problem area for AEMO and aspiring developers.
It has some of the best wind and solar resources in the state but, despite warnings going back more than a decade, does not have enough grid capacity.
“The capacity of the existing network to host large scale inverter-connected generation has been reached,” AEMO says in a stakeholder notice, in reference to existing and “committed” projects.
“New and existing generation across large parts of the WMZ will be materially constrained for significant periods of time pending large-scale network investments.
“This will not only restrict commercial output but may prevent or delay completion of commissioning for new projects. Connections that rely on future regulated upgrades to the network cannot be assessed until those upgrades are substantially complete.”
AEMO says there are now 21 wind and solar generators with a total capacity of 1.5GW in “full operation” in the West Murray Zone. A further eight projects with a total capacity of 1.1GW have been registered and are in the commissioning stage.
But there are also more than 25 wind and solar projects wanting to join the grid within the Western Murray Zone and currently in the application phase.
The West Murray Zone has already seen five big solar farms have their output cut in half for more than seven months due to uncontrolled “oscillations” that were finally solved through the fine-tuning of inverters.
Many other projects have been heavily delayed in connection and commissioning, as AEMO implemented a cautious “sequencing” system that processed projects one at a time. It is now looking to adopt that in other areas of the grid.
And wind and solar farms are also regularly subject to output constraints depending on the local conditions and energy flows in the grid.
It will only likely be solved by new transmission infrastructure. The new $2.3 billion transmission link from Robertstown in South Australia to Wagga Wagga in NSW will include a “spur” to Buronga and Red Cliffs, but a new transmission link within Victoria is also needed.
Ausnet is working on a proposed new 180km link from Bulgana in the north to Sydenham, near Melbourne, dubbed the Western Victoria Transmission Upgrade Project, but that has run into issues over its planned route, and a fall-out with consumer representatives who have criticised its consultation process. Even if built on time, it will not be completed until 2025.