Busbar Classification - Results GZ12 West Coast

System Operations

Transpower New Zealand Limited

June 2017

Version Date Change

1 01/06/2017 Draft

2 01/08/2017 Final – no changes from draft

Position Date

Prepared By:

Reviewed By:

IMPORTANT

Disclaimer

The information in this document is provided in good-faith and represents the opinion of Transpower New Zealand Limited, as the System Operator, at the date of publication. Transpower New Zealand Limited does not make any representations, warranties or undertakings either express or implied, about the accuracy or the completeness of the information provided. The act of making the information available does not constitute any representation, warranty or undertaking, either express or implied. This document does not, and is not intended to; create any legal obligation or duty on Transpower New Zealand Limited. To the extent permitted by law, no liability (whether in negligence or other tort, by contract, under statute or in equity) is accepted by Transpower New Zealand Limited by reason of, or in connection with, any statement made in this document or by any actual or purported reliance on it by any party. Transpower New Zealand Limited reserves all rights, in its absolute discretion, to alter any of the information provided in this document.

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Contact Details

Address: Transpower New Zealand Ltd 96 The Terrace PO Box 1021 Wellington New Zealand

Telephone: +64 4 495 7000

Fax: +64 4 498 2671

Email: system.operator@transpower.co.nz

Website: http://www.systemoperator.co.nz

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Contents 1 Results of Analysis for West Coast .................................................................................................. 4

1.1 Arthurs Pass 66 kV Bus ........................................................................................................... 4 1.1.1 N-1 (normal conditions) ....................................................................................................... 4

1.2 Castle Hill 66 kV Bus ............................................................................................................... 5 1.2.1 N-1 (normal conditions) ....................................................................................................... 5

1.3 Coleridge 66 kV Bus ................................................................................................................ 6 1.3.1 N-1 (normal conditions) ....................................................................................................... 6

1.4 Dobson 110 kV and 66 kV Bus ............................................................................................... 7 1.4.1 N-1 (normal conditions) ....................................................................................................... 7

1.5 Greymouth 66 kV Bus ............................................................................................................. 8 1.5.1 N-1 (normal conditions) ....................................................................................................... 8

1.6 Hokitika 66 kV Bus .................................................................................................................. 9 1.6.1 N-1 (normal conditions) ....................................................................................................... 9

1.7 Hororata 66 kV Bus ............................................................................................................... 10 1.7.1 N-1 (normal conditions) ..................................................................................................... 10

1.8 Kumara 66 kV Bus ................................................................................................................. 11 1.8.1 N-1 (normal conditions) ..................................................................................................... 11

1.9 Otira 66 kV Bus ..................................................................................................................... 12 1.9.1 N-1 (normal conditions) ..................................................................................................... 12

1.10 Additional Buses .................................................................................................................... 13

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1 RESULTS OF ANALYSIS FOR WEST COAST

It is assumed that N-1 is the contingency of a bus section with all other equipment in the network in

service (normal conditions). N-1-1 is the contingency of a second bus section with the first bus section

on planned outage at the same bus; all other equipment in the network is assumed to be in service.

A busbar is a single bus section; a bus can be made up of one or more bus sections.

1.1 ARTHURS PASS 66 KV BUS

Region: West Coast Normal configuration: One busbar APS 66 kV bus has one bus section with two circuits: COL-CLH-APS and APS-OTI. The circuit breakers at CLH and APS have no protection so faults are cleared by opening the COL and OTI circuit breakers. Load will be lost at CLH and APS. Depending on the local generation and load at the time, local voltage excursions may be experienced.

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1.2 CASTLE HILL 66 KV BUS

Region: West Coast Normal configuration: One busbar CLH 66 kV bus has one bus section with two circuits: COL-CLH and CLH-APS-OTI. The circuit breakers at CLH and APS have no protection so faults are cleared by opening the COL and OTI circuit breakers. Load will be lost at CLH and APS. Depending on the local generation and load at the time, local voltage excursions may be experienced.

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1.3 COLERIDGE 66 KV BUS

Region: West Coast Normal configuration: One busbar COL 66 kV bus has one bus section with four circuits: COL-CLH-APS-OTI-1, COL-HOR-2 and 3, COL-OTI-2. There is no bus zone protection at COL so bus faults remove all connected circuits from service. Load and generation at COL will be lost. The circuit breakers at CLH and APS have no protection so the COL-CLH-APS-OTI-1 110 kV circuit is cleared by opening the COL and OTI circuit breakers. Load will be lost at CLH and APS. Depending on the local generation and load at the time, local voltage excursions may be experienced.

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1.4 DOBSON 110 KV AND 66 KV BUS

Region: West Coast Normal configuration: One busbar This is also discussed in GZ9 Nelson as DOB 110 kV is in GZ9. DOB 66 kV bus has a single bus section with one circuit DOB-GYM 66 kV. The bus section has two 110/66 kV transformers, one goes to ATU-DOB-1 110 kV circuit and the other goes to DOB-RFN-IGH-2 110 kV circuit. There is no ‘physical’ 110 kV bus. There are also two 66/33 kV supply transformers which supplies DOB load. ALD generation is embedded in the 33 kV system. Loss of DOB 66 kV bus will result in loss of the 110 kV connections, the single 66 kV circuit, DOB load and ALD generation. Depending on the local generation and load at the time, local voltage excursions may be experienced.

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1.5 GREYMOUTH 66 KV BUS

Region: West Coast Normal configuration: One busbar GYM 66 kV bus has one bus section with two circuits: GYM-KUM and DOB-GYM. Loss of this bus section will result in loss of load at GYM. Depending on the local generation and load at the time, local voltage excursions may be experienced.

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1.6 HOKITIKA 66 KV BUS

Region: West Coast Normal configuration: One busbar HKK 66 kV bus has one bus section with two circuits: HKK-OTI-2 and HKK-KUM-1. Loss of this bus section will result in loss of load at HKK. Depending on the local generation and load at the time, local voltage excursions may be experienced.

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1.7 HORORATA 66 KV BUS

Region: West Coast Normal configuration: One busbar HOR 66 kV bus has one bus section with four circuits: HOR-KBY-ISL-1 and 2, COL-HOR-2 and 3, Loss of the bus section will result in loss of HOR load. Depending on the local generation and load at the time, local voltage excursions may be experienced. The West Coast will be connected through Dobson and will be on N security via DOB-GYM 66 kV circuit. Should this circuit overload and trip, the West Coast will be lost. Transpower does not actively manage assets on N security.

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1.8 KUMARA 66 KV BUS

Region: West Coast Normal configuration: One busbar KUM 66 kV bus has one bus section with three circuits: KUM-OTI-1, HKK-KUM-1 and GYM-KUM. Loss of this bus section will result in loss of load at KUM and generation at KUM and DIL. Depending on the local generation and load at the time, local voltage excursions may be experienced.

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1.9 OTIRA 66 KV BUS

Region: West Coast Normal configuration: One busbar OTI 66 kV bus has one bus section with four circuits: COL-CLH-APS-OTI-1, COL-OTI-2, OTI-KUM and HKK-OTI-2, Loss of the bus section will result in loss of load at OTI, APS and CLH. Depending on the local generation and load at the time, local voltage excursions may be experienced.

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1.10 ADDITIONAL BUSES

Below is a list of buses where the incoming circuit feeds directly into a transformer and/or each bus section is not connected to the other sections (other than through the lower voltage side) or the bus is no longer a Transpower’s asset. Loss of a bus section will affect only the load and generation connected to it. There are no other system issues expected. KBY 66 kV bus sections are each teed into one of the HOR-KBY-ISL-1 and 2 66 kV circuits and each section feeds directly into a supply transformer.