Electricity Asset Management Plan 2019-2029
97
Vector Limited://
below in Section 4.5. The CBARM model for conductors is fully developed and is used to inform our programme of replacement for the subtransmission overhead network.
The present specification for wooden crossarms requires a life of 40 years. Crossarms are actively replaced based on inspections, age and criticality. The use of composite crossarms is being trialled at present.
4.3 ZONE SUBSTATIONS Overview
Zone substations are the electrical nodes from which the 33 kV, 22 kV and 11 kV distribution network emanate into Vector’s supply areas. Zone substations house Vector’s 110 kV, 33 kV, 22 kV, and 11 kV primary switchgear, 110 kV/33 kV, 110 kV/22 kV, 33 kV/11 kV and 22 kV/11 kV power transformers and battery energy storage systems. Zone substations also house the associated ancillary equipment necessary for the primary equipment to function appropriately and to be remotely controlled such as: ripple plant, local supply transformer, auxiliary systems such as the DC system, SCADA systems, and network communications connection equipment, inverters and solar systems to power the AC ancillary services. In the Northern area, the 33 kV subtransmission network is highly interconnected and a number of zone substations are equipped with a single transformer with N-1 security then supplied from neighbouring zone substations via the 11 kV distribution network. In the Auckland CBD, bulk supply substations are interconnected with 22 kV express interconnectors and 22 kV distribution feeders to provide N-2 security of supply to CBD bulk substations. Vector also has a transportable 11 kV switchboard that can be moved to different locations as a substitute switchboard when a zone substation is out of service for project work or when a failure occurs at a zone substation. The transportable unit contains 11 kV switchgear and auxiliary systems similar to those found in our fixed zone substations. Population and Age Key statistics of zone substations are summarised in the table below. Schedule 12b in Appendix 9 shows the peak loading, capacity and constraints statistics of all Vector’s zone substations.
No of 110 kV zone substations 9
7
No of 33 kV zone substations
85
No of 22 kV zone substations 10
18
No of BESS zone substations
3
No of transportable 11 kV switchboards
1
No of transportable transformers 11
2
Table 4-6 Key statistics for bulk and zone substations
Condition and Health A programme of works to achieve seismic compliance for our zone substation buildings in accordance with NZ seismic standards and the NZ Building Code is nearly complete and the last zone substation to be upgraded, Northcote, will occur in FY19. We have experienced the ‘leaky homes’ failure mode for a number of zone substations built in the early 2000s and one in particular, Sandringham, required extensive reconstruction. Brick and concrete block substations are ageing but kept in good condition with appropriate and timely maintenance.
―
9 Lichfield, Liverpool, Hobson, Quay Street, Kingsland, Pacific Steel, Wairau 10 Highbrook has been included in the list although this is a 22 kV switching station 11 2.5 MVA 400 V/11 kV transformer for the connection of temporary generation
Made with FlippingBook - professional solution for displaying marketing and sales documents online