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Auckland Blackout - NOT a Third-World Power System


Monday’s power cuts affected almost a tenth of Vector’s customers. Some customers from the Waikato to Northland were affected, as well as those in Auckland. Auckland Mayor John Banks has described the region’s power supply as “third-world”, but a more accurate description is “could do better”.

One lines company, Orion, is doing a good deal better. Power supply to Christchurch and onwards to the top of the South Island is limited by transmission capacity, and has been so since the 1990s. Orion set its network prices to encourage its commercial and industrial users to reduce their demand at peak times. By doing this, Orion kept prices down by delaying the need to upgrade the transmission. It also achieved the most reliable supply in the country.

With the 2011 Rugby World Cup looming, we can be assured this kind of power emergency will not be repeated during the event next year. These power cuts coincided with the end of the summer holiday period, when both of Auckland’s gas fired power stations were out for routine maintenance. All of Auckland’s electricity was being supplied from the south. Six big lines could easily carry the load – but two of those were being upgraded, so the whole load was carried by the remaining four. For the World Cup, we can be sure that all power stations and lines will be available.

The more load a line carries, the longer it gets – this makes it sag. Though Monday’s power cut has not been fully analysed, it seems likely that one sagged close to the shelter belt, and the arc set fire to it. Transpower declared a grid emergency, and Vector and other companies immediately used all available hot water ripple control. That was not enough – the second line – on the same set of poles – also got hot and failed.

Transpower called up the long-planned rationing system, and Vector responded by cutting off about 10% of its customers. All customers are warned, as part of their customer contract, that power supply can fail at any time – everyone needs to have a plan for how they will manage power cuts of hours or even days. People with medical needs for electricity must be prepared to transfer to a hospital or another facility if they cannot back up their equipment’s power supply.

The rationing system works by prioritizing which customers should receive electricity first. It involves a list of customers on each local power line arranged in a priority order to ensure that hospitals, water supply, sewage treatment, and other essential services are the last to be cut off. A second list is kept of lines which will not be rationed, and would automatically be cut off in the event of a larger failure.

These lists are prepared by each lines company in consultation with Transpower, and revised twice a year. This protects the whole national grid from a catastrophic power failure. This is not “third-world”. It is a proper arrangement to minimize the impact of unavoidable power system failure.

Monday’s blackouts might have been avoided if Transpower had notified Vector of the outages of two power stations and of one third of transmission capacity into Auckland, and if Vector had a means of paying larger customers to reduce peak demands at critical times.

If the Mayor (right) is still worried about further outages this summer, why doesn’t he talk with Vector – owned by the Auckland Electricity Consumers’ Trust –about how they might make it worthwhile for large customers to reduce their demand at peak times? Perhaps the City Council facilities might be a good place to start.

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