Transpower this morning issued a nationwide warning notice - revealing there was a risk of insufficient power generation and reserve to meet the country's demand - as Kiwis woke to a bitterly cold day.
The state-owned enterprise issued the warning today as the first big winter chill has hit this week, with Kiwis most likely pumping their heaters.
Transpower CEO Alison Andrew said this morning's grid emergency was due to losing generation from three sources including a Contact Energy power station, Genesis' power station in Huntly and a wind drop from 90 to 30 megawatts.
"This morning we called a grid emergency just before 8am, which is during the morning peak, to make sure we could stabilise grid security."
Speaking to Newstalk ZB's Kerre Woodham, Andrew said the emergency was all over by 9.30am and most consumers wouldn't have noticed.
Lines companies were asked to reduce their controllable load which impacts things like hot water cylinders, said Andrew.
"As a system operator we have to manage the power system in real time and when these situations happen we need a good response from our industry participants to make sure we keep the lights on for New Zealanders."
Asked how the entity would handle a similar situation in a future where everyone was driving electric vehicles, Andrew said they are working hard to find new ways to be able to respond.
She said there is a lot of interest to build renewable energy sources in New Zealand, with over 100 inquiries, but that this work comes with peculiar challenges and solutions for dry years and winter peaks need to be found.
"At Transpower we are working hard to make sure we have the capacity to connect people up to the grid for their new demand or generation as quickly as we can."
The notice, which was issued at 7.58am, said "This is a New Zealand-wide emergency".
"The System Operator advises there is a risk of insufficient generation and
reserve offers to meet demand and provide N-1 security for a contingent event."
A spokesperson for Transpower said that generation issues this morning meant they had to ack quickly to restore residual generation.
"We've managed the system well... we had to take action which we did quickly, lines companies helped with that."
According to the Electricity Authority, N-1 means that the system is planned such that, with all transmission facilities in service, the system is in a secure state, and for any one credible contingency event, the system moves to a satisfactory state.
The notice stated that if participants insufficiently respond to the emergency warning then the system operator will have to manage demand to alleviate the Grid Emergency.
"The system operator may instruct the grid owner to disconnect feeders without further notice to connected parties."
Participants were requested to increase energy offers, to increase instantaneous reserve offers and to decrease demand by using controllable load, that is not offered as instantaneous reserve, and increasing distributed generation.