Electricity Asset Management Plan 2019-2029
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Vector Limited://
• Utilising temporary generation; increasing vegetation cut zones; removing trees that can fall on lines, and limiting third-party assets strikes (these options are under the control of the government, councils and other infrastructure providers, as well as consumers) • Using emerging technology like fuel cells to improve resilience • Shared resilience options, where the cost quality trade-off analysis results in options that meet the required resilience through on-premise customer solutions, at a more efficient investment level than a network solution. This can be fully funded by the customers or partially funded by Vector Microgrids Ensuring resilience in remote areas using traditional network solutions is often costly relative to the number of customers served. We are always looking at smarter and cost effective ways to meet the requirements of our customers in areas on the edges of our network with modest growth but with inadequate quality of supply performance, (mainly driven by the exposure of the existing network to climate change effects such as strong winds). A good case to point is Kawakawa Bay in the remote south-eastern edge of Vector’s rural network that is supplied via a very lengthy 11 kV overhead line for which an alternative backup supply by means of a traditional network solution would be prohibitively expensive. This is where employing self-sufficient microgrids becomes a viable economic alternative. Most microgrids are network-connected, but they can ‘island’ themselves during an outage. This means those connected to them can access back-up power, and this improves remote communities’ resilience in a cost-effective way. Undergrounding Even though undergrounding seems to have obvious reliability advantages – such as reduced exposure to lightning, and fewer outages as a result of adverse weather, including falling trees, EDBs cannot simply underground entire networks. The cost would create an unmanageable burden for consumers (an estimated $5.5 billion to underground the remaining 45 percent of Vector’s overhead network). An overhead network also has a long economic life – 40 years – and were an EDB to prematurely replace it with an underground network there would be a significant cost impact on future generations since costs are recovered over 40 years. Undergrounding is not a panacea for all risks either. There are challenges and disadvantages apart from the high cost of such a huge venture. Disadvantages include: replacement is more costly and difficult; fault-finding and repair times for underground cables are much longer (which drives up maintenance costs and duration-based reliability indices) and the cables are at more risk during floods and earthquakes. Sharing roading corridors with other utility services such as water, gas, communication and trees can lead to congestion and cable de-rating. Distribution Automation We are increasingly automating distribution with the aid of remotely controllable or automated devices that increase both the visibility and controllability of our distribution system. We have installed devices such as reclosers that are circuit breakers that trip on faults but will automatically reclose if the fault is transient. Remotely controlled feeder switches, used in conjunction with these reclosers, can open and close feeder sections as required to isolate a faulty section of feeder so there may not be a requirement to send out a linesman to undertake manual switching that in turn removes the time associated with driving between isolation points in the network.
Automated distribution is improving our resilience through:
• Sectionalisation – isolating the affected section to minimise the number of customers affected • Better diagnosis – pinpointing the section affected, so the fault can be found faster • Restoration – this can be done remotely and automatically
Vector has deployed 136 high voltage auto-reclosers since 2007. We have also deployed 209 remotely controlled feeder switches. This programme of work will continue throughout this AMP period (see Section 5).
Smart Meters Advanced meters at the customer’s premise are essentially a sensor that have the ability to capture a range of information that is useful to Electricity Distribution Businesses (EDBs) to plan, optimise and manage the network. Information regarding voltage levels, network performance and the impact of new technology on the network such as EV and solar are critical to ensuring that the network can continue to support customer choice going forward. In addition, the advanced meters currently installed at customer premises can also provide accurate information regarding which premises are without power.
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