SRAS REVIEW TASMANIA REGION

July 2013 PRESENTED BY PETER BIDDLE SLIDE 1

AGENDA

1. The System Restart standard 2. What are the recommended changes

a) Main assumptions b) Electrical sub-networks c) Quantity of SRAS d) SRAS Definition

3. Restart process 4. Questions 5. Summary

SLIDE 2

SYSTEM RESTART STANDARD

• Procure sufficient SRAS to achieve the following targets in each electrical sub-network; o Provide auxiliary supply to sufficient generation within 90 minutes to provide generation & transmission capacity to meet 40% of peak demand within 4 hours • For Tasmania peak demand = 1800 MW • Need to supply 720 MW capacity within 4 hours • The restoration timeframe represents the target timeframe to be used by AEMO in the procurement process. It is not a specification of any operational requirement that should be achieved in the event of a black system condition SLIDE 3

RECOMMENDED CHANGES

• Current assumption is that SRAS is procured to manage a NEM wide shutdown o Changing to a Region only shutdown • NEM wide shutdown requires each region to be self supporting for SRAS o Region only shutdown allows use of adjoining regions as a restart supply however this is not possible for Tasmania • Currently two electrical sub-networks in Tasmania o Recent strengthening of the network between the north and south and the fact that the majority of generation in Tasmania is hydro based making it quick to restart provides incentive to consider Tasmania as a single electrical sub-network.

• Currently three SRAS in Tasmania – two of these are combination services SLIDE 4

PROPOSED CHANGES (CONT.)

• Current SRAS o o o Reece – located in and allocated to the current north electrical sub-network Poatina/Cethana sub-networks.

– located in the current north electrical sub-network but allocated to both north and south electrical Gordon/Trevallyn sub-network.

– located in both north and south electrical sub-networks but allocated to the south electrical o Map • If Gordon SRAS was unavailable then the entire Tasmania region would be required to be restarted from the north electrical sub-network. SLIDE 5

RECOMMENDED CHANGES (CONT.)

• Current definitions of primary & secondary SRAS has led to a number of perverse outcomes o small gas turbines starting large thermal units at the same power station that do not assist in AEMO meeting the System Restart Standard because:  No output to transmission network for several hours  Do not assist in restarting other generating units o Contracting with diesel units used to restart hydro and gas turbine generating units  Makes testing difficult and inefficient SLIDE 6

RECOMMENDED CHANGES (CONT.)

• Recommending a single SRAS definition • Objective is to ensure contracted services assist AEMO in meeting the System Restart Standard o ≥ 100MW delivered to the local transmission bus within 60 minutes.

 Availability/reliability ≥ 90%  Could be delivered by • TTHL • Hydro • Gas Turbines • Other o Testing would involve black starting the unit, connecting to the power system and increasing output to contracted output within the contracted timeframe.

• AEMO is currently consulting with a number of generators to see if changes to this proposal are warranted. SLIDE 7

RESTART PROCESS

• Under AEMO’s proposal Tasmania will have a minimum of two restart sources o 2 x strategically located SRAS o Electrical / geographic / technology diversity • A restart will normally start from both sources concurrently.

o For the purpose of this exercise we will assume one SRAS is not available so restart will be managed from a single SRAS.

• The aim is to provide auxiliary supply to the majority of power stations within 90 minutes.

o If this is done then the time to restore supply capacity is minimised but is then outside AEMO’s control.

 Load restoration determined by rate at which power stations can restore capacity  Smelter load is a sensitive load and auxiliary supply must be restored within 75 minutes and full supply within 2 hours, exceptional circumstances accepted.

SLIDE 8

SOME ASSUMPTIONS

• As currently accepted o All generation & transmission equipment is available for service o Generation capability is in accordance with Local Black System Procedures as provided by Generators o Reasonable time frames allowed for restoration of transmission elements o o Load can be restored for voltage control Major generation • West Coast – Reece, John Butters, Bastyan, Tribute, Mackintosh • Mersey Forth – Cethana, Devils Gate, Fisher, Lemonthyme/Wilmot.

• North – Poatina, Tamar Valley, Trevallyn • Derwent – Tungatinah, Tarraleah, Meadowbank, Liapootah/Wayatinah/Catagunya • Gordon o o Sufficient staff available at AEMO/TNSP/DNSP/Generator There are potentially a number of ways to do this  Largely based on current Tasmania region system restart plan.

SLIDE 9

RESTORATION FROM PALMERSTON NORTH

• Assume Poatina is the SRAS • Restore Palmerston 220/110KV bus via SRAS Palmerston. Set voltage < 223/115KV – auxiliary supply/connection to 360 MW at Poatina made available. Restore local load at • Restore 110KV connection to Trevallyn bus via Hadspen – auxiliary supply/connection to 100MW at Trevallyn made available • Restore 220KV connection between Palmerston & Hadspen and restore 220/110KV Transformer at Hadspen. Set Hadspen voltage < 225KV • Restore 220KV connection to George Town via Hadspen. • Restore auxiliary supply to Pacific Aluminium smelters • Restore 220KV connection between George Town and Tamar Valley Auxiliary supply and connection available to Tamar Valley 220KV generation • Energise 110KV bus at George Town – made available to Tamar Valley 110KV generation.

auxiliary supply/connection SLIDE 10

PALMERSTON TO TREVALLYN & GEORGE TOWN

SLIDE 11

RESTORATI0N FROM PALMERSTON (CONT.)

• Restore 220KV connection between George Town & Sheffield and energise 110KV bus • Restore connection from Sheffield to Railton – auxiliary supply/connection to 270 MW of generation from the Mersey Forth area.

• Restore 220KV connection between Sheffield and Farrell and energise 110KV bus – voltage at Sheffield < 225KV prior to this step.

• Restore connection from Farrell to Rosebery/Queenstown auxiliary supply/connection to 600 MW of generation from the West Coast.

• Restore Sheffield – Palmerston 220KV line.

• Auxiliary supply now available to the majority of generation in the north & west of Tasmania. • Auxiliary supply available to the smelter and can be loaded as generation becomes available.

SLIDE 12

GEORGE TOWN TO MERSEY FORTH & WEST COAST

SLIDE 13

RESTORATION FROM PALMERSTON SOUTH

• Can be done at the same time as the north restoration • Restore Palmerston to Liapootah • Restore Liapootah to Wayatinah/Catagunya – supply/connection made to 170 MW of generation at Liapootah/Wayatinah/Catagunya. auxiliary • Restore connection to Chapel Street and energise 110KV bus.

Minimum 3 units at Poatina/Liapootah for voltage control. Restore approximately 30MW load ex Chapel Street to manage voltage for next step. Chapel Street < 222KV.

• Restore connection to Gordon – auxiliary supply/connection to 420MW generation made available SLIDE 14

PALMERSTON TO GORDON

SLIDE 15

RESTORATION FROM PALMERSTON SOUTH

• Restore 110KV connection from Chapel St to New Norfolk • Restore 110KV connection to Meadowbank – auxiliary supply/connection made available to 40 MW of generation • Restore 110KV connection between Meadowbank and Tarraleah auxiliary supply/connection made available to 90 MW of generation • Restore 110KV connection between Tarraleah and Tungatinah - auxiliary supply/connection made available to 125 MW of generation at Tungatinah • Restore 110KV connection from Tungatinah to Palmerston via Waddamana SLIDE 16

RESTORE DERWENT VALLEY GENERATION

SLIDE 17

TIMING ESTIMATES TO MAKE AUXILIARY SUPPLY AVAILABLE

• Elapsed time = 30 minutes o Poatina • Elapsed time = 60 minutes o o Trevallyn Mersey Forth o o Tamar Valley (includes Pacific Aluminium) Liapootah/Wayatinah/Catagunya • Elapsed time = 90 minutes o o West Coast Gordon • Elapsed time = 120 minutes o Derwent 110KV SLIDE 18

AFTER 4 HOURS – LIKELY SUPPLY CAPACITY

• The majority of generation capacity is expected to be available due to the nature of the plant.

o System Restart Standard requires 720MW • Some stations may have energy limitations due to water supply.

• After approximately 900MW of supply has been restored Basslink may be returned to service.

SLIDE 19

SUMMARY

• Region only shutdown • Move to a single electrical sub-network • Two SRAS to be procured with geographic and electrical diversity • Revised SRAS definition • Expect to be able to provide auxiliary supply/connection to all major generation within 90 minutes even with only one SRAS • Rate of load restoration will depend on rate of generation restoration and is outside AEMO’s control.

SLIDE 20