A fault at a gas field in the North Island sparked low generation warnings by Transpower, says an electricity company.
The national grid operator issued two “low residual” customer advice notices on Tuesday, explaining that electricity generation was “tight” amid further sub-zero temperatures around parts of the country.
The notices were in place between 5.30pm and 8pm yesterday and again for today between 7am and 8.30am.
A similar notice was issued by Transpower last month, warning power companies they may be unable to meet demand if there are any unexpected failures in the North Island amid freezing overnight temperatures around much of the country.
A more serious grid emergency notice was issued earlier this year as the result of an “unusually strong solar storm”.
A customer advice notice refers to electricity generators, local lines companies and major industrial customers connected directly to the grid, rather than electricity consumers.
A Transpower spokesperson said the notices were issued as part of its procedures working with industry with the electricity supply stretched “due to the ongoing cold snap”.
“They call for more electricity generation to be made available and prepare the industry to respond if the situation deteriorates, for instance if it is colder than forecast or wind generation drops below forecast during the peaks.
“We do not expect any impact on consumers’ electricity supply and would communicate publicly if that assessment changes.”
Meridian general manager of wholesale Chris Ewers told RNZ he understood a fault at a major gas field in the North Island had occurred.
“As a result it’s taken out some generation with it in the North Island.
“The power system relies on generation supply and demand.
“It’s not at the level where it’s of concern to operations at this point. But it’s just one step further along the continuum of where we just pay a bit of attention, and make sure that everything we have available is available.”
Transpower issued two excursion notices on Tuesday for “equipment tripping” at Huntly and Kopu, Coromandel.
The operator said there was a mix of factors that caused the notices.
“There are a range of variables involved in the supply and demand balance.
“These include the availability of generation units, transmission outages that may constrain generation, what the wind is doing (it’s low and variable and we saw downside risk over the peaks), and temperature and hence demand (the cold snap has increased demand and we were factoring in the chance it could be colder than forecast).”
Ewers said extreme cold and plant failures concurrently was one scenario that could spark an emergency grid notice and potential blackouts.
“We’ve actually have quite a large amount of load response in play at the moment from the NZAS Demand Response.
“So the system is not in the same type of situation as we were in 2021.”
Transpower was fined $150,000 last year after 34,000 households lost power during one of the coldest days of the year in August 2021.
After the latest pair of warnings were issued, Transpower said the industry had responded as expected
“We don’t expect any issues with low residual generation on [Wednesday morning].”
Wintry blast ‘good news’ for hydro lake levels
Meridian said the ongoing wintry blast that had moved up the country in recent days had brought welcome relief to dwindling hydro lake levels in the South Island.
Last month, national grid operator Transpower said hydro storage lake levels were the lowest they had been in more than 20 years.
Lake Pukaki in inland Canterbury was recorded at historic lows only a few weeks ago.
It has continued to rise steadily and it is now less than two metres below average for this time of year
Ewers said snowfall had helped replenish the lakes in the Waitaki catchment.
Last week hydro levels sat at 83% of its average levels, but heavy dumpings of snow had propelled it up to 105%.
“When it comes to topping up lake levels, snow is just as welcome as rain.
“While rain almost immediately helps increase the level of Lake Pūkaki, all that snow on the mountains above the lake is invaluable later in the year when the temperature heats up and rain becomes less frequent.
“It’s like having another lake.”
Ewers said hydro catchment capacity was looking good for the next three to six months.
