PB POWER

PEER REVIEW OF CHOICE OF VOLTAGE FOR
DEVELOPMENT OF THE NEW ZEALAND GRID

CONFIDENTIAL

Prepared for

TRANSPOWER

In association with Beca Simons Ltd

PB Power Quality System:
Document Reference
:
p:\152171-RPT-001
Report Revision
:
0
Report Status
:
Final
Prepared by
:
Bruce Stedall (PB Power)

Don Lyon (Beca)
Reviewed by
:

Eric Wolters

Approved by
:

Eric Wolters

Date Created
:
19 February 2004

Date Issued
:
19 February 2004

Over a Century of

Quality Management System Certified to ISO 9001: 1994
Engineering Excellence

PB Power
Peer Review of Choice of Voltage for Development of the New Zealand Grid

EXECUTIVE SUMMARY
PB Power was employed by Transpower to undertake a high level review of the Transpower long term
proposals for developing the New Zealand Grid, and particularly whether the Grid should be
developed at 400 kV or 500 kV. Using accepted demand forecasts and various future generation
scenarios, Transpower had identified an initial need to enhance transmission infrastructure initially in
the corridors between Whakamaru and Otahuhu in the North Island, and between Livingstone and
Islington in the South Island using a combination of load related and aging asset drivers. Transpower
identified voltage elevation to 400 kV as the best option in both cases.
PB Power undertook a review of technical and economic issues, and Beca Simons a review of
Resource Consenting issues. Our conclusions and recommendations are summarised below.
Technical Review
Our review found that, based on technical considerations, the upgrade to 400 kV is the most
appropriate choice for the Whakamaru-Otahuhu circuit, consistent with the long term requirements for
the development of the grid. In the case of the Livingston-Islington circuit, both 220 kV and 400 kV
options provide technically feasible means of enhancing the transmission capacity.
In either case, there is no clear advantage in adopting 500 kV over 400 kV.
Economic Review
The transmission line and substation unit costs used by Transpower to assess economic viability are
consistent with our international experience.
Stringent audible noise limits rather than thermal ratings govern the conductor size used as a basis for
the 400 and 500 kV designs. Overhead line costs could be reduced by between 10-15% by aligning
audible noise limits with international best practice. A review should be undertaken to establish an
acceptable degree of noise for the design of the future overhead lines in New Zealand.
For the North Island, we consider there to be a robust economic case for elevating the voltage to
400  kV, whether considering a 10-15 or 40 year planning period. There is no economic case for
choosing 500 kV over 400 kV, even taking into account the reduced losses.
For the South Island, the economic studies carried out to date indicate that there is no case for
upgrade to 500 kV and that the Net Present Value difference between 220 kV and 400 kV options is
marginal. The benefits of the 400 kV option are realised only in the longer term when there is greater
uncertainty, whilst continued development at 220 kV is capitally efficient in the short term and still
provides an economically comparable solution to the 400kV in the longer term. It is recommended
that supplementary economic analysis, using alternative methods to Net Present Value analysis are
undertaken to provide a clearer differentiation between 220 and 400 kV options.
Recognising the uncertainty in the longer term and the present difficulty in obtaining land easements
and Resource Consents, Transpower should consider developing 400 kV construction overhead lines
to be operated initially at 220 kV, thus deferring substation and transformation costs and securing the
route until such time as demand and generation forecasts provide a more robust economic justification
for the upgrade.
Resource Management Act
Consentability of any grid enhancement option will be increased with a robust evaluation of the ‘need’
and benefits of the project relative to a do-nothing or do-minimum option or one based largely on the
existing or an expanded 220 kV grid. Transpower will need to counter arguments promoting
embedded generation increases over grid enhancement.
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It is not possible to undertake a detailed comparison of 400 kV and 500 kV solutions on environmental
grounds at this stage. However at a strategic level, it is likely that 400 kV would have less impact
whilst offering the same long-term benefits.
Conclusion
The Transpower proposal for the introduction of 400 kV on certain transmission corridors, with
continued development on other transmission corridors at 220 kV is considered to be appropriate.
There is no advantage in adopting higher transmission voltages than 400 kV.
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1. INTRODUCTION
1.1 BACKGROUND
Transpower has undertaken an investigation into New Zealand’s future electricity supply
needs. As part of the investigation it has made forecasts of (or sourced from other
published data) the growth in electrical demand over the next 40 years. The peak
demand of about 6,200 MW in 2003 is expected to double by 2040. This corresponds to
a load growth of about 2 per cent / annum.
To supply this demand additional generation has been projected. Recognising the
uncertainty associated with the type and location of future generation a number of
alternative generation scenarios have been postulated.
Transpower has taken the forecasts of electricity demands and generation scenarios and
modelled them against the existing capabilities of New Zealand Grid. From this
Transpower has identified parts of New Zealand Grid that require enhancement,
technically feasible options for facilitating the enhancement, and when they are required.
These options were assessed against a number of criteria and Transpower’s conclusion
was that introducing 400 kV is the optimal development option for New Zealand.
1.2
SCOPE OF REVIEW
This Report presents a high level review of the Transpower proposals for developing the
New Zealand Grid, particularly that aspect associated with whether the Grid should be
developed at 400 kV or 500 kV.
In undertaking the review PB Power has focused on the techno-economic justifications
behind the Transpower proposals for developing the New Zealand Grid. As such, the
load forecast and background generation scenarios have been taken as read. The focus
of the review has been on the methodology employed, the assumptions made and the
overall conclusions, not on the presentation quality of previous reports.
The documents that were reviewed are listed in Appendix A.
1.3
STRUCTURE OF REPORT
This Report is structured as follows:
•  The Executive Summary provides a summary of our conclusions and
recommendations
•  Section 1 comprises this brief introduction, including an appreciation of the
background to the work.
•
Sections 2, 3 and 4 present the findings of our review, categorised into Technical,
Economic and Resource Management Act aspects.

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2. TECHNICAL
REVIEW
2.1 GENERAL
There is an immediate need to consider options for enhancing transmission infrastructure
in the corridors between Whakamaru and Otahuhu in the North Island, and between
Livingstone and Islington in the South Island, particularly recognising the lead times
associated with transmission projects. However, there are other parts of the New
Zealand Grid which will need reinforcement to meet demand from generation sources
over the next 10-40 years.
The transmission infrastructure in the Whakamaru-Otahuhu corridor transfers power
generated in central and southern part of North Island combined with transfers from
South Island to the major load centre of Auckland accounting for about one third of the
country’s demand.
The Livingstone-Islington corridor transfers power generated largely by hydro-electric
plant in central and southern part of South Island to the load centre of Christchurch
accounting for about one sixth of the country’s demand.
In assessing options for upgrading the supplies to Auckland and Christchurch
Transpower has sought to review the voltage of electrical transmission to ensure
optimised development of the New Zealand Grid.
Experience shows that, if there is a need to migrate to another system voltage, the next
system voltage level should be about twice the existing voltage level. With the current
principal transmission voltage in New Zealand being 220 kV, this suggests voltages of
either 400 kV or 500 kV, the ultimate choice being a function of a number of factors
including:
•
The distance over which power transfers are required.
•
The load density.
These are discussed in relation to the New Zealand system in the following sections.
2.2
THE NEW ZEALAND SYSTEM
The North Island accounts for two thirds of the demand of New Zealand and, as indicated
previously about one third is consumed in Auckland alone. The remaining one third of
the demand is associated with the South Island with a large proportion consumed in
Christchurch.
Over the 40 year planning period transfers on a number of corridors will require
reinforcement depending on the assumed generation although a number of
reinforcements would be required irrespective of the generation background. Transpower
have considered options for meeting these transfer needs, from which individual circuit
transfers may be derived. The forecast corridor transfers and expected worst case circuit
loads for affected circuits under n-1 contingency conditions are shown in Figure 1 and
Figure 2 for the North Island and South Island respectively. Figure 1 and Figure 2 also
show typical transfer capabilities of circuits at 220 kV, 400 kV and 500 kV although these
may vary slightly depending on the choice of conductor and overhead line configuration.
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Figure 1 North Island - transfer capability at various voltage levels compared to
expected corridor and circuit transfers.
3500
3300 MW - 2040 Whakamaru-Auckland maximum corridor transfer
Variance in length of
3000
circuits in circuits in
North Island
2500
t (MW)
ircui 2000
C
500 kV
1500
1300 MW - 2040 Bunnythorpe-Whakamaru maximum corridor transfer
1100 MW - 2040 Stratford-Whakamaru maximum corridor transfer
1000
1100 MW - 2040 Maximum circuit transfer
400 kV
Power Transfer /
500
220 kV
0
50
100
150
200
250
300
350
400
Distance (km)

Figure 2 South Island - transfer capability at various voltage levels compared to
expected corridor and circuit transfers.
3500
Livingstone-Islington circuit length
3000
2500
t (MW)
ircui 2000
C
500 kV
1500
1400 MW - 2040 Livingstone-Islington maximum corridor transfer
900 MW - 2040 Livingstone-Islington maximum circuit transfer (400 kV option)
1000
400 kV
Power Transfer /
800 MW - 2010 Livingstone-Islington maximum corridor transfer
500
220 kV
300 MW - 2040 Livingstone-Islington maximum circuit transfer (220 kV option)
0
50
100
150
200
250
300
350
400
Distance (km)

In the North Island, the Whakamaru-Otahuhu, Bunnythorpe-Whakamaru and Stratford-
Whakamaru corridor transfers are forecast to increase to about 3,300 MW, 1,300 MW
and 1,100 MW respectively over the planning period. The number of additional circuits
required to secure these transfers under contingency conditions is shown in Table 1.
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Table 1 Requirements for additional circuits to secure corridor transfers by 2040
Corridor
220 kV
400 kV
500 kV
Whakamaru-Otahuhu 8/2 4  3
Bunnythorpe-Whakamaru 41
2 2
Stratford-Whakamaru 42
2 2
1. Comprises 2 x Bunnythorpe-Whakamaru circuits and 2 x Bunnythorpe-Rangipo circuits
2. Comprises 1 new double circuit and 1 rebuilt double circuit with heavier construction
Therefore whilst there may be an argument for the introduction of 500
kV to
accommodate transfers in the Whakamaru-Otahuhu, the capacity would be overly high
for transfers required in the Bunnythorpe-Whakamaru and Stratford-Whakamaru corridor.
400 kV is therefore considered to be an appropriate technical solution for the North
Island.
In the South Island, with the exception of the Livingstone-Islington transmission corridor,
the magnitude of power transfers on the Grid is such that there is no clear case for
considering the elevation of voltage to either 400 kV or 500 kV.
Therefore, for the majority of South Island it is considered that development of the
Grid should continue at 220 kV. Transpower reached the same conclusion.
In the case of the Livingstone-Islington transmission corridor, the argument is whether
there is a need at all to elevate the voltage from the existing level of 220 kV. This is
particularly the case as whilst the Livingstone-Islington corridor transfer can be as high as
1,400
MW, the maximum circuit loading is about 300
MW and 900 MW under
contingency conditions for the 220 kV and 400 kV options respectively.
A review of the proposals indicates the following alternatives:
Continued 220 kV development:
•
By 2010 construct a 220 kV double circuit overhead line from Livingstone-Islington.
•
By 2030 construct a 220 kV double circuit overhead line from Twizel-Islington
•
Refurbish existing 220 kV existing single circuit overhead lines.
400 kV development:
•
By 2010 construct a 400 kV double circuit overhead line from Livingstone-Islington.
•
Decommission existing 220 kV existing single circuit overhead line from Livingstone-
Islington.
As can be seen, the next reinforcement is required by 2010 but in the case of continued
220 kV development refurbishment or rebuild works on the existing infrastructure is also
required, with further reinforcement required a further 20 years into the planning horizon.
In summary  both 220 kV and 400 kV options can be shown to provide technically
feasible means of enhancing the transmission capacity between Livingstone and
Islington.
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2.3 OVERHEAD
LINE
DESIGN
The design of the overhead line has been largely dictated by audible noise and electro-
magnetic fields requirements. The audible noise limits used as a basis for the design are
demanding in comparison to international best practice whilst those for the electro-
magnetic fields increase the height of the tower. The levels of audible noise calculated
by Transpower have been verified by PB Power independently. This is commented on
further in Section 4 but recognising the impact of meeting audible noise requirements on
the overhead line design, a review should be undertaken to establish acceptable degrees
of noise for the design of the future overhead lines of New Zealand.
The overhead line has been designed for a 50°C operating temperature.  For a modern
design 75°C or 85°C is the usual criteria.  However, in the case of Transpower’s
proposals, it is the audible noise criteria rather than the thermal limit requirements that
are constraining. Should the audible noise criteria be relaxed such that, say, a 3 x Goat
bundle as opposed to the currently proposed 4 x Goat bundle is required for 400 kV
construction overhead lines, the 50°C operating temperature would require review. This
will also affect the cost of the overhead line.
2.4 REACTIVE
COMPENSATION
In the case of 400 kV and 500 kV development options it is of note that switched reactive
compensation has been incorporated at 220 kV. It is understood that this has largely
been incorporated to ensure voltages are maintained within ±10 per cent limits and
reactive capabilities of generation plant are not exceeded, particularly under light load
conditions.
However, it is unclear if this compensation will provide appropriate overvoltage control at
either 400 kV or 500 kV during line energisation, particularly recognising that certain of
these circuits are of the order of 250 km in length. This should be confirmed as part of
the detailed design. It is however recognised that this would make the case for 500 kV
even less attractive when compared to 400 kV.

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3. ECONOMIC
REVIEW
3.1 UNIT
COSTS
Transpower has determined unit costs of equipment to be used as building blocks in the
consideration of alternative options for developing the New Zealand Grid. The unit costs
include design, installation and commissioning costs but exclude on-costs associated
with Transpower’s inputs to the projects.
These unit costs may be broadly categorised into overhead line and substation costs:
3.1.1
Overhead Line Costs
Transpower have produced preliminary designs of overhead lines to determine unit costs.
The costs have been based on assumed line routings and terrain; the requirements to
ensure appropriate insulation and statutory clearances whilst accommodating bare hand
live line work; operate at 50°C, ensure adherence to audible noise and electro-magnetic
fields; and are based on the provision of an optical ground wire.
These costs are consistent within budgetary tolerances of costs on international projects
that PB Power has been involved with. Transpower also indicates that the overhead line
costs have been found comparable to CIGRE benchmarks and as expected the costs are
biased to reflect the requirements imposed by certain councils on levels of permitted
audible noise. However, it is of note that the audible noise limits used as a basis for the
design are demanding in comparison to international best practice. Overhead line costs
could be reduced by between 10-15% by aligning audible noise limits with international
best practice.
It is also of note that technical studies associated with the 500 kV development analysis
have assumed that the 400 and 500 kV overhead lines will have the same conductor
configuration. From a load flow perspective this is a valid assumption. However to meet
environmental requirements a larger conductor size will be needed for the 500 kV option.
This would have the effect of approximately halving the transmission losses attributed to
the 500 kV circuits compared to the 400 kV option and improving its economic Net
Present Value. That does not however alter the overall conclusions drawn from the
economic analysis.
3.1.2 Substation
Costs
These costs are consistent, within budgetary tolerances, with costs on international
projects that PB Power has been involved with.
3.2 ECONOMIC
ANALYSIS
METHODOLOGY
Economic analysis has been undertaken using traditional cost-benefit analysis
techniques for alternative options for developing the Grid, known in New Zealand as
National Benefit Test. The National Benefit Test is largely the same as the Australian
Consumer and Competition Commission (ACCC) Market Benefit Test and therefore may
be considered to have been tried and tested.  In summary, for the alternative options the
national benefit is calculated from:
National Benefit =  Present Value [local generation cost – grid generation cost]

+ loss savings compared to 220 kV

- Present Value [ project capital cost + operating/maintenance costs]
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Economic as opposed to financial analysis has been undertaken for comparing options
which in our opinion is the appropriate mechanism for undertaking the assessment.
The overall economics of the proposals for developing the New Zealand Grid have been
assessed over a 40 year period consistent with depreciation of these assets over their
lives. Whilst assessments over such a period are the norm for state owned utilities, a
period of 10-15 years can be more appropriate, particularly where the company is
privately owned. The choice depends on the way in which transmission investments are
financed, the degree of certainty with respect to demand and generation, and the lead
times associated with satisfaction of environmental and consenting issues.
3.3 NORTH
ISLAND
ANALYSIS
The analysis undertaken by Transpower concludes that developing the interconnection
between Whakamaru and Otahuhu at 400 kV is the most economic compared to 500 kV
(or 220 kV and 330 kV) based on a 40 year planning period. In the case of a 10-15 year
planning period in which there is more certainty associated with the investment,
combined with the need to address current constraints on the network, supplementary
analysis carried out by Transpower at our request confirms that 400 kV is still the
optimum choice.
For the North Island, therefore, it is considered that there is a robust economic
case for elevating the voltage to 400 kV, whether considering a 10-15 or 40 year
planning period.
There is no economic case for choosing 500 kV over 400 kV.
3.4 SOUTH
ISLAND
ANALYSIS
Developing the interconnection between Livingstone and Islington at 400 kV is more
economic compared to 500 kV based on a 40 year planning period. However the Net
Present Value analysis shows 220 kV and 330 kV to be even more economic, albeit
within tolerances that do not permit distinction of alternatives.
In the case of a 10-15 year planning period in which there is more certainty associated
with the investment, development at 220 kV is sufficient to address current constraints on
the network. There may be an argument for introducing 400 kV construction overhead
lines that would initially be operated at 220
kV, thus deferring substation and
transformation costs, until such time as there is more certainty in the development of
demand and generation. This would also provide environmental and operational benefits
through the decommissioning of existing 220 kV single circuit overhead lines.
However, the 40 year Net Present Value analysis also makes no clear case for 400 kV
over 220 kV. Both 220 kV and 400 kV alternatives are similar in that they trigger capital
spend in 2010 but different in that the 220 kV option requires rebuilding and/or
refurbishment of existing 220 kV infrastructure and a further reinforcement in 2030. The
benefits of 400 kV are only realised in the longer term when there is greater uncertainty
(and therefore risk of stranded assets). Continued development at 220 kV is capitally
efficient in the short term and still provides an economically comparable solution to the
400 kV given the uncertainty of planning 25 years into the future.
In summary, for the South Island, the economic studies carried out to date indicate
that there is no case for upgrade to 500 kV and that the Net Present Value
difference between 220 kV and 400 kV options is marginal. It is recommended that
supplementary economic analysis, using alternative methods to Net Present Value
analysis are undertaken to provide a clearer differentiation between 220 and 400 kV
options.
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Recognising the uncertainty in the longer term and the present difficulty in obtaining land
easements and Resource Consents, Transpower should consider developing 400 kV
construction overhead lines to be operated initially at 220 kV, thus deferring substation
and transformation costs and securing the route until such time as demand and
generation forecasts provide a more robust economic justification for the upgrade.
3.5 SUPPLEMENTARY
ANALYSES
For completeness, a sensitivity analysis (in which the economic case is tested at
tolerance limits of projected demand, costs, etc) would be useful, particularly between
400 kV and 500 kV development scenarios. Further, the use of Net Present Value
analysis as a means for discriminating on economic grounds between South Island
220 kV, 330 kV and 400 kV options has not yet identified a clear choice. It would be
helpful if supplementary analysis was undertaken to draw out the differential between
these options.
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4.
RESOURCE MANAGEMENT ACT IMPLICATIONS
4.1 APPROACH
Within the limited scope of this review it has not been possible, nor is it appropriate to
evaluate in detail all work being progressed by Transpower’s in house Environmental
Team. Further, it is understood from discussions with Transpower that in house work is
currently focussed on a 400 kV option. Evaluation of a 500 kV option is limited to
extrapolating the likely environmental effects from a 400 kV option based on the
significant differences in design and construction between options.
By necessity then, this peer review is limited to a high level evaluation of the key
differences between the two options and the relative consenting challenges which might
(to a greater or lesser extent) impact upon the feasibility of either option.
4.2
CONSENTING A GRID ENHANCEMENT PROJECT
The general approach to consenting any of the grid enhancement options will be similar
regardless of voltage selection. This is because the consenting regime under RMA is
essentially the same for all projects, and secondly, because the range of effects (though
not the scale or extent) to be considered are common to all options. These effects can be
summarized as land use and property impacts, visual and landscape impacts, noise and
EMF effects, construction, social and cultural effects, and positive social and economic
effects due to security of supply.
Our understanding is that the above effects are all subject to assessment by Transpower
and there is nothing to suggest that any significant effects have been ignored in work to
date.
A key ‘test’ will be to establish a robust case to demonstrate that it is necessary to move
from ‘do nothing’ and secondly that a ‘do minimum’ scenario is not sustainable in the
medium to long term. This will address challenges to the validity of a grid enhancement
option (regardless of voltage selected) and will primarily need to address two key issues:
•
Whether additional grid capacity is necessary given the potential for an increase in
local generation (i.e. what is the case for strong national grid)
•
Why is the existing 220 kV system near capacity and/or the end of its useful life.
The material reviewed suggests there is strong evidence on both these points. It is
recommended that this be presented in lay terms for the consenting process including an
evaluation on the timing or staging options.
4.3
CHOICE OF 400 KV OR 500 KV
The RMA does not require Transpower to select the best practicable option from an
environmental perspective, rather Transpower must demonstrate that it has considered
alternatives, and that in doing so, it has taken reasonable steps to avoid, remedy and
mitigate significant adverse effects for the preferred option. The preferred option will be
identified on a variety of criteria, environmental factors being only one of these.
As indicated earlier, it is not possible to make a detailed comparison of the options. A
further complication arises, as all options will cross a multitude of district and regional
boundaries with a variety of district and regional plans and a diverse environment/
community through which the grid passes. This complication can be arrested by use of
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the designation powers of the RMA to achieve consistency on a national basis, however
some regard must still be had to local conditions in the design and consenting process.
At a high level it is possible, on the basis of the limited peer review undertaken, to identify
some broad distinctions between the environmental effects of 400 kV and 500 kV options:
•  Land Use/Property Impacts – The material reviewed shows circuit length will be
similar for both options (and offer some benefits over an enhanced 220 kV solution).
A 500 kV option is likely to require a wider easement and have greater property
impacts than 400 kV, however it is not simply a matter of assuming that, say a 10%
increase in easement width (on average) will result in a 10% increase in either
impacts or land costs. This can only be assessed in detail based on an indicative
corridor alignment, as even a small easement increase may on some properties
mean that it is better to purchase a property outright than secure a wider easement.
In this regard land cost estimates (which are a big ticket item) must be viewed with
real caution. In an urban context wider easements could be a significant constraint
and cost differential.
In summary the analysis suggests 400 kV is a better option from a land use and
property perspective. However Transpower must ensure that it demonstrates that
400 kV has adequate long-term capacity and avoids the need for further circuits
later, which might otherwise be avoided if 500 kV were selected as the design
standard.
•
Visual and Landscape Effects – 500 kV requires taller towers which in general will
have greater impact than 400 kV provided circuit length stays the same. In general
400 kV should be less intrusive, provided that it has long-term capacity to avoid
additional circuits later.
•
Noise and EMF Effects – It is understood that noise generation and EMF are both
greater for a 500 kV network. In general a 400 kV network will be preferred
especially in urban areas and will be more compatible with New Zealand’s generally
low ambient noise environment.
A night time (most restrictive) noise limit between 37dBA(leq) to 42dBA(leq) at the
notional boundary of a dwelling (say 5-25m from the façade) would be typical in most
districts however Transpower will need to select a suitable criteria on a national
basis. In an urban context easement boundaries may be close to dwellings, whereas
in rural areas dwellings would be more distant. It is understood that Transpower has
used the easement boundary to assess noise. This may be appropriate in urban
areas, but on average, perhaps too onerous in rural areas.
•  Construction Impacts – Based on a similar circuit length there is little difference
between options, though access for larger 500 kV infrastructure will present some
additional challenges.
•  Social and cultural impacts – These are related to property impacts. It is also
possible that a 500 kV network will exacerbate feelings of intrusion and severance
especially in urban areas.
•
Economic Benefits – Both options give NZ security of supply which is a significant
benefit. Whilst not directly relevant to RMA, there may be criticism about wastage
and over design if the capacity from a 500 kV solution is grossly above forecast
demand over say the next 25 years.
4.4 CONCLUSIONS
Consentability of any grid enhancement option will be increased with a robust evaluation
of the ‘need’ and benefits of the project relative to a do-nothing or do-minimum option or
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one based largely on the existing or an expanded 220 kV grid. Transpower will need to
counter arguments around local generation increases making a national grid less
relevant.
It is not possible to undertake a detailed comparison of a 400 kV and 500 kV solution on
environmental grounds at this stage. However at a strategic level, it is likely that 400 kV
has less impact, whilst offering the same long term benefits, provided the capacity of a
400 kV solution is adequate without the need for additional circuits in the foreseeable
future.

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APPENDIX A
References

PB Power
Peer Review of Choice of Voltage for Development of the New Zealand Grid

References
1.  System Security Forecast, 2001/02
Transpower NZ Ltd
2.  Common Quality Obligations, April 2003
Transpower NZ Ltd
3.  High Level Grid Augmentation Plan, 9 Oct 03
Chandra Kumble,
Transpower NZ Ltd
4.  Review of Transpower High Level Grid Augmentation Plan
Dr. Brian Nuttall, PB Power
Report, 10 Feb 2004
Ltd
5.  Report on Comparison of 400 kV and 500 kV Transmission
Mohamed Zavahir and
Development
Prahlad Tilwalli,
Transpower NZ Ltd
6.  Selection of Next Voltage, February 04
Chandra Kumble,
Transpower NZ Ltd

Document Outline