Aurora Energy investigates Central Otago power outages

Chief Executive Richard Fletcher said the company is looking into the causes. “At this stage it seems the two major outages in Clyde/Alexandra in January that impacted close to 8,000 customers, were most probably triggered by third party interferences on the network and not related to failure of equipment.

“Having said that, the network settings which control how faults are managed in real-time did not respond as expected so more customers than necessary were impacted.” Mr Fletcher said the problem had now been fixed.  

“We are also double checking the network equipment on the two circuits in question to confirm our initial view. This will include an acoustic ground-based and infrared drone-based inspection later this month.” He said Aurora Energy would share more information when this work had been completed.

“We apologise for the inconvenience to our customers. We know that any unplanned power outage is frustrating and want to reassure customers that our network is sound,” Mr Fletcher said.

Matt Settle, Aurora Energy’s General Manager Operations and Network Performance said, “Aurora Energy reviews every unplanned outage but there are times when we cannot determine the cause. Adverse weather such as lightning strikes or ‘high’ wind contact with lines, or interference by birds and other animals are all potential causes.  

“In these circumstances, our electricity lines are designed to isolate the fault and trip the circuit for safety reasons. Depending on the location of the fault, this will determine how many customers are impacted. In most cases, power can only be restored after our teams have undertaken a line patrol inspection,” Mr Settle said.

Around a quarter of unplanned power outages each year are categorised as ‘unknown cause' and for the year ended March 2022, it was approximately 20%. This is comparable to other lines companies in New Zealand and is reported to the Commerce Commission.

Notes:

The Central Otago network includes some of the most remote and rural areas of Aurora Energy’s network, with some long spans of line serving proportionately fewer customers. Some of these lines are at the end of the local network, such as the Omakau and Ettrick areas. These areas have no alternative options to back feed electricity if there is an outage, unlike in an urban area where there may be several back feed options available.

Over the past five years, Aurora Energy has renewed large parts of the network across Central Otago through our largely safety- and capacity-driven customised price path investment plan that was agreed with the Commerce Commission in 2021.

Some parts of the network still need reliability improvements. Aurora Energy’s forward-looking 10-year investment plan, to be submitted to the Commerce Commission and made public on 1 April this year, looks to shift the investment focus from addressing historic safety related investment backlog issues to network reinforcement. This is designed to meet growth and target improvements at known reliability hot spots.

Aurora Energy’s significant and ongoing network investment programme is essential to ensure we can meet future demand and means we need to remove assets from service more frequently than previously. This results in a temporarily reduced security of supply and introduces more operating complexity, creating an increased but localised vulnerability to faults.

Additional information regarding the new zone substation and generator in Omakau

Aurora Energy is building a new zone substation in Omakau, which will be completed by mid-2024 (before winter). A larger transformer will double the supply capacity, ensuring it can meet growing demands of the community.

The new substation will have a fixed generator that is able to provide power supply for most of the community if we need to take the current lines out of service to undertake maintenance. This also provides some back up generation if an extended unplanned outage occurs in the main electricity line. However, the generator cannot be used for every unplanned outage due to the delicate balance required to manage load fluctuations in real time.

We are also in the process of implementing a new technology trial on the line from Alexandra to Omakau to detect emerging faults in real time, thereby enabling defect remediation prior to causing an outage to customers.

ENDS

For further information please contact Aurora Energy’s Customer and Engagement Team, [email protected] or (03) 742 0931