26 August Update Regarding Conductor Repair

27 August 2021

Repairs were completed and the HVDC Pole 2 returned to Service at 1:00pm Thursday 26 August.

A full investigation into the conductor fall will take some time as we will need to run extensive testing on the tower and conductor, to identify where the failure occurred, and why.

 

Information Update 24 August

Severe weather conditions in the Weka Pass have delayed the completion of conductor stringing for the repair of the HVDC Pole 2 circuit

High winds pose a significant risk to the health and safety of staff, who are also operating under COVID-19 Alert Level 4 restrictions. Weather conditions do not look to improve until Thursday.

The final piece of work requires a small crew working up the most exposed tower on the ridge line to make final connections.

Winds today are gusting to over 80km/hr on site. Forecast for Wednesday is for slightly stronger winds.

As a result, the completion of the repair has been pushed out to Thursday 26 August 16:00 weather dependent.

 

Information update 21 August

Transpower has extended the anticipated timing for the completion of the HVDC Pole 2 repair out to Tuesday 24 August at 4:00pm

 

Information update 20 August

Transpower has announced outages of the HVDC is required for the safe repair of the HVDC conductor in Weka Pass.

The timing of the outages is carefully chosen to avoid peak demand.

This is not a unique event - at least once a year, both HVDC Poles are out for maintenance.

Each island generates enough electricity to meet its own demand during these times when round power (the sharing of power between the islands) is disabled.

 

Information provided August 19

Transpower has changed its expected date for the return of the HVDC Pole 2 from Sunday 22 August 4:00pm to Monday 23 August

This information has been shared with market participants and the industry

 

Information provided August 18

What occurred on August 17?

One of the High Voltage Direct Current (HVDC) conductors (wire) fell across State Highway 7 in the Weka Pass area, Waikari in North Canterbury. No one was harmed.

 

What is the latest?

Last night the road was cleared and reopened with the fallen conductor elevated above the road via hurdles.

On site assessments last night and today have revealed six towers which normally hold the conductor have been damaged as part of the failure.

 

Repair of the conductor:

We have crews on site now and work is well underway to plan the repairs.

Replacement equipment and conductor has been dispatched for delivery to site. The safety of our people is of the upmost priority particularly now we are operating under COVID-19 Alert Level 4 protocols.  

The terrain, ground conditions, and current and forecast weather is making the work challenging.

We have informed the market that we do not expect to have this conductor back in service before Sunday 22 August at 4:00pm.

 

What is being done to manage the supply of electricity while repairs are undertaken?

Demand is currently down around 15% and we expect this trend to continue while in Alert Level 4 lockdown.

We are in regular communication with industry regarding the situation, how demand is looking and what our level of supply is.

We are currently forecasting sufficient supply to meet demand this evening and out for the rest of the week, barring a major plant failure.  

 

Why did the conductor fall?

Our primary focus is to repair the issue. The investigation into why the conductor fell, will take time to complete.

Early indications are that this was a one-off fault and not a systemic issue.

 

What was Transpower’s response to the event?

We issued a Grid Emergency asking for increased generation and for electricity distribution businesses (lines companies) in the North Island to reduce all controllable demand (such as hot water).

The industry responded accordingly and Transpower was able to maintain the stability of the system nationwide without any disconnections.