Transend - Appendix 5 Renewal capital expenditure - Australian ...

Table 1 – Cost comparison of options considered
1
2a
2c
3b
Option
Upgrade of both Tarraleah and
Tungatinah switchyards in-situ
Consolidate at Tungatinah with fully
selectable double bus AIS
Consolidate at Tungatinah with double
bus AIS and back-to-back connections
Remote site using gas-insulated
switchgear (GIS)
SKM estimated capital
cost of option
($2005 million)
Net present value of
option ($2007 million)
excluding Brownfield
factor
0BInvestment Evaluation Summary
TNM-GS-809-0720
Net present value of
option ($2007 million)
including 20 percent
Brownfield factor
$11.31 -$15.45 -$18.18
$11.62 -$16.17 -$18.97
$11.15 -$15.26 -$17.95
$14.11 -$17.89 -$17.89
3c Remote site using hybrid switchgear $12.97 -$16.50 -$16.50
On the basis that SKM identified an AIS solution as the lowest capital cost option, Transend prepared a detailed scope
and estimate for this option. Details of the scope are provided in document ‘Tungatinah Substation 110 kV
redevelopment – project definition form’ (TRIM D08/20858). At a high level, the basis for the estimate includes the
following key activities:
� redevelop Tungatinah Substation 110 kV switchyard by:
o replacing the remaining switchgear, conductors and string-insulator assemblies of obsolete design and
manufacture (ie. re-use recently replaced equipment where practicable);
o replacing and relocating all protection and control schemes to improve functional performance;
o rationalise switching arrangements by removing the ring bus; and
o segregating transmission assets from their existing location in the power station to provide independent SCADA
and DC supplies, together with security against fire, flood and intruders.
� redevelop Tarraleah Switching Station 110 kV switchyard by:
o replacing all switchgear, conductors and string-insulator assemblies of obsolete design and manufacture;
o replacing and relocating all protection and control schemes to improve functional performance;
o rationalising equipment by relocating identified switch-bays to Tungatinah; and
o segregating transmission assets from the power station location to provide independent SCADA and DC
supplies, together with security against fire, flood and intruders.
� removal of sub-standard transmission line clearances by:
o ground profiling/replacement of structures on TL424 (TA–TU, west); and
o removing the Boyer Tee Structure and over-passing the Boyer Tee Structure site.
� rationalise switching arrangements to improve constructability, operability (protection and network performance)
and maintainability; and
� consolidate Transend’s protection and control assets at a new control building at Tungatinah Substation.
A summary of the various components of Transend’s estimates is provided in Table 2.
© Transend Networks Pty Ltd 14 of 15