Rarotonga’s power supplier Te Aponga Uira (TAU) acknowledged recent power outages were caused by issues with load control and a connection between their two powerhouses, assuring the public they have identified the problems and fixed them.

The government-owned enterprise has apologised for the recent power outages and assured the public that they are unrelated to the recent upgrades, which were completed over a week ago.

Rarotonga residents experienced unexpected island-wide power outages for three consecutive nights starting Tuesday. The outages, lasting from 15 minutes to over two hours, occurred between 6.48pm and 9.10pm.

The outage on Thursday night lasted the longest. There was an island-wide power outage at 6.30pm, briefly returning at 6.57pm before a longer outage starting at 7pm that lasted over two hours.

In a statement issued to Cook Islands News last night, TAU said Thursday’s outages were directly attributable to the load control challenges brought on by network reconfiguration necessary for power supply, as a result of the cross- island cable fault.

The recent upgrades have not directly caused these issues, the power supplier said.

“This particular outage was caused by the connection between our two Rarotonga powerhouse switch rooms, which balance demand and supply across the island. Immediately this occurred, we reached out to our specialist partners to identify the issue, perform the necessary load calculations and recalibrate the controls,” the statement said.

“We, and those specialists, are confident we have fixed this issue.”

TAU said on Tuesday evening, its power station noted an additional, unidentified, source of power adding significant electrical energy to the network.

“As our control systems are designed to do, they automatically shut down the entire network to protect the network from damage. We were able to get the system back up and running, and started investigating the cause of this issue,” the statement said.

“While those investigations were ongoing, there was a recurrence Wednesday evening.

“We successfully identified that issue on Thursday morning. It had been caused by one of the BESS solar energy batteries automatically discharging energy at a time and at a level outside its design parameters. We are investigating this issue with the supplier to ensure it does not happen again, and in the meantime, we have isolated all BESS solar energy batteries from the network so that this cannot recur.”

TAU chief executive Lesley Katoa said they have not lived up to expectations and these outages have gone beyond a minor inconvenience given the timing and frequency.

“TAU apologises to the community. We have not lived up to expectations and these outages have gone beyond a minor inconvenience given the timing and frequency,” Katoa said.

“The outages have been caused by two unrelated issues, and my team supported by our NZ counterparts are confident they have identified what’s gone wrong and how to fix them.”

Katoa said they strive, continually, to provide reliable electricity to their customers and to visitors.

“Unfortunately, this week we have not been able to do so … we assure our customers that we do have the ability to supply enough electricity to meet demand.

“Our ability to generate enough power to meet demand is not the issue.”

Following outages on Thursday night, Rarotonga-based engineer Reuben Finch shared some insights on Friday morning regarding what he believed were causing the disruptions.

Based on his findings, Finch concluded that the system was overloaded.

“Some parts of the new ‘upgraded’ system can’t handle the nightly usage. So I think the only thing we as consumers can do is ‘load-level’,” he said in a Facebook post.

“If possible, try and shift our heavy power use to either side of normal. Perhaps we can help out by rotating our heavy electricity use around the island?”

According to Rarotonga-based engineer Reuben Finch, “some part of the new 'upgraded' system can't handle the nightly usage. We are also dangerously close to morning black-outs, looking at the graph”. SUPPLIED (FACEBOOK)/24062806

Speaking to Cook Islands News, Finch explained that his main reason for posting his findings on Facebook was to urge the island to change the timing of their electricity use. He said his graph showed the system, in its current form, is “not able to manage the load”.

“I worry how three consecutive evenings in the dark is damaging for restaurants, takeaways, accommodation providers and Cook Islands tourism in general. Not to mention all the locals who are eating dinner and trying to get their children bathed and ready for bed in the dark,” he said.

“Given TAU advertised the replacement of the switchgear recently I would assume that is the culprit, but I have no specific evidence. I don’t recall three consecutive blackouts with the old system.”

Finch added that TAU needs to be asked to let the community in on what they have repaired during the last three nights.

“A couple of times the power has come back on, then cut out for longer. So I assume a safety circuit is triggering and then the operators are just resetting the system and hoping, but then it fails again due to a further issue,” he added.

TAU’s Katoa said: “These recent events, highlight the complex nature of providing reliable electricity on an island such as ours, with the mix of renewable and non-renewable generation capability and with infrastructure that operates in a challenging marine environment.”

“This week’s occurrences demonstrate the challenges of maintaining a careful balance of how much electricity can be delivered through various networks to our people right around the island.

“We are a small, capable team here in Rarotonga, supported by experts from New Zealand, Australia, and further afield who have been available, in real time, to provide prompt remedy, fault-finding and re-calibration.

“I thank all those people – both with Te Aponga, and overseas support personnel, who have been working extremely hard for long hours in recent days. And not to forget our valued customers for your patience and understanding, we will continue to work hard to deliver what you expect and deserve.”