Voltage fears force AEMO to cut solar farms output

Output from five solar farms in Victoria and NSW has been sliced in half by the market operator, ­citing concerns over voltage issues.

Output from five solar farms in Victoria and NSW has been sliced in half by the market operator, ­citing concerns over voltage issues potentially hitting the power grid.

The Australian Energy Market Operator said four solar units in northwest Victoria and one in NSW’s Broken Hill would have limits imposed following studies conducted on several local transmission lines. The Victorian solar farms affected are Foresight’s Bannerton ­facility near Robinvale, Bay-Wa’s Karadoc plant south of Mildura, and Wirsol’s Wemen plant near Mildura and Gannawarra farm west of Kerang.

The NSW solar farm is AGL Energy’s Broken Hill unit in the southwest of the state.

“AEMO is working closely with a number of solar farms and network service providers to manage identified voltage fluctuations in the North West Victorian and South West NSW region of the National Electricity Market,” the operator said. “Close analysis and management of this issue is required to ensure power system security across the associated parts of the Victorian and NSW 220 kV electricity network.”

The solar units will roughly see their output cut in two, according to new solar farm limits for the five farms published by AEMO on its website yesterday.

New generation standards and system strength requirements have been put in place to ensure solar and wind maintain grid stability, with AEMO noting that following a trip on transmission lines the solar farms had shown “oscillatory behaviour”.

“Until the fluctuations are resolved, AEMO will need to partially constrain the affected generators to manage power system security,” it said. “AEMO has been working closely with all impacted generators, and anticipates an expedited remediation, reducing the impact and time frame of required constraints.”

Energy expert Tristan Edis wrote on Twitter that the situation was “ugly although fixable” and suggested synchronous condensers may need to be installed as part of the fix.

The clampdown follows AEMO imposing tougher rules on connecting to the grid and a reduction in so-called marginal loss factors — which determine the prices generators get for their power — which has diminished returns for many renewable operators along with price volatility in the market.

The derating of some solar developments in the pipeline may mean owners struggle to give the investment green light to projects.

AEMO, which runs the nation’s power grid, has proposed “urgent” transmission investment in western Victoria over concern that the state’s existing network will fail to cope with a surge in clean energy supplies, potentially sparking a long-term price jump for users.

Up to 6000 megawatts of large-scale wind and solar generation will enter the grid in a decade, with a third of that supply due to come online by next year, driven by an increase in the state’s renewable energy target to 50 per cent by 2030.

The plan for western Victoria envisages major transmission works including a new terminal station north of Ballarat and long-distance voltage lines between Bulgana and Sydenham, with the final component not due in place until 2025.

Elevated power prices also ­remain a significant issue for the Coalition government, which is under pressure to deliver on an election promise for wholesale tariffs to fall by up to 25 per cent to $70 a megawatt hour by 2021.