Yarrawonga power supply upgrade works

Last summer, there was an increase in outage activity in the Yarrawonga area.

We appreciate how frustrating these interruptions were, particularly on very hot days.

We have reviewed the outages in detail and identified a range of contributing factors, including:

• Voltage stability issues
• Equipment faults
• Severe weather and strong winds
• Vegetation contacting powerlines
• Extreme heat
• In some cases, no clear fault cause could be identified

These issues mostly impacted one of the two supply lines that supply Yarrawonga and surrounds.

The other factor was that on Total Fire Ban days, mandatory line patrols must be completed before power can be restored. This can lead to longer than normal restoration times. which can also extend outage durations.

Yarrawonga is supplied by two main powerlines from Cobram East. The recent outages affected only one of these lines, so only customers connected to that line were impacted.

The generators did help meet increased demand in Yarrawonga. For example, there was eight days in a row of temperatures above 40 degrees at one point, but there were no supply issues during that time.

The outages we saw across summer were related to a series of faults with one powerline in particular.

We have started on a package of works to strengthen Yarrawonga’s power supply.

The works, which are an acceleration of planned upgrades for the area, follow a detailed review of outages that affected some customers earlier this year. The review found a combination of equipment faults, extreme heat, vegetation contacting powerlines during high winds and other network issues contributed to the interruptions experienced across parts of the network. In some cases, no clear cause could be identified.

The upgrades include:

• Installing new regulators to help keep electricity flowing consistently through the network and reduce the risk of outages.
• Replacing an 8km section of powerline with larger lines capable of carrying more electricity when demand is high.
• Raising a 30km section of powerline higher, so it can safely carry more electricity during periods of extreme heat.
• Upgrading key cables at start of the line out of the Cobram East Zone Substation, to allow for greater electricity flow.
• Installing new switches, poles and associated infrastructure to provide more flexibility to the existing network.

A second phase of work will begin next year and will include upgrades to a powerline supplying the Bundalong area. As part of normal summer preparations, a generator will be placed in Bundalong to provide backup support if faults do occur.

Voltage regulators are important for keeping volts at a stable level for all customers – no matter where they live along the line – and are especially important for long rural powerlines, like this one.

Volts tend to drop over long distances and between the start of the line and the end of the line, there’s a whole lot of customers both drawing power and injecting power that impacts volt levels across the powerline’s three phases.

That’s where the regulators come in.

They’re strategically positioned at certain points along the line to bring the volts back to the correct level and let that electricity continue on its way.

These larger regulators we’re putting in can handle far more power flow than the ones you had and will absolutely help with supply problems going forward.

When power flows through a conductor, it heats up and this can make the powerline sag lower.

We have rules to follow about not letting powerlines get too low for safety reasons, so by tightening up or lifting up this part of the line, we can run it a bit hotter, allowing more power to flow through.

No. We have not turned off power to the region. In fact, we’re doing everything we can to keep power on.

These outages were caused by local issues on the network, not wider supply problems.

Not at this stage.

Yarrawonga currently receives power from the Cobram East zone substation. This station is able to supply the town with what it needs and has space to be expanded in the future as growth continues. It is common for one station to supply several nearby communities.

If the town and surrounding areas continue to grow, a new station may be needed in the future, but at this stage this is not expected for more than 10 years.

They will provide extra capacity for customers in this line.

We are exploring other improvements to meet the growing needs of the area in the medium and long term.

These options include potentially installing another major powerline in the region.

We expect this work may be needed in the next five years and we will keep the community updated as we progress these plans.

This was not a power supply issue.

This was an issue with one of the two supply lines that feed the area.

If your outages exceed 18 hours in total or more than eight interruptions in a financial year, you may be entitled to a Guaranteed Service Level payment. These are processed automatically through your retailer and are stated as a credit on your retail bill. For details, visit: https://www.esc.vic.gov.au/electricity-and-gas/information-for-electricity-and-gas-consumers/guaranteed-service-level-payments-energy-outages-and-voltage-claims.