Power System Adequacy 2012

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POWER SYSTEMADEQUACYFor the National Electricity Market

2012


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POWER SYSTEM ADEQUACY

ii Executive summary AEMO 2012

[This page is left blank intentionally]

Published by

AEMOAustralian Energy Market OperatorABN 94 072 010 327

Copyright 2012 AEMO


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AEMO 2012 Executive summary iii

EXECUTIVE SUMMARY

Reserve capacity, energy adequacy, operational capacity, and frequency control

Results from the 2012 Power System Adequacy (PSA) reports two-year outlook assessment (using projections

developed for the 2012 National Electricity Forecasting Report (NEFR1) and supply capabilities as advised by

market participants) established the following key points:

The reserve capacity and energy adequacy assessment indicates that the power system will have sufficient

supply capacity to meet the Reliability Panels reserve requirements, and (as at the time of publication) the

Australian Energy Market Operator (AEMO) is not expecting to invoke the Reliability and Emergency Reserve

Trader (RERT)2

tender process to maintain supply reliability in the National Electricity Market (NEM).

The operational capacity assessment indicates that significant new operational issues are unlikely.

An area of possible concern involves the adequacy of frequency control during periods of high wind

generation and the electrical separation of parts of the transmission network. AEMO is currently working to

address this issue, which involves the design of over-frequency generator trip schemes and assessing optionsto ensure frequencies in the affected regions remain within the operating standards.

Power system sensitivity

The sensitivity analysis involving the impact from an unplanned NEM-wide withdrawal of older generation totalling

1,000 MW from 1 July 2012 onwards indicates that supply reliability will be sufficient to meet the Reliability Panels

reserve requirements.

The results also suggest that other areas of power system adequacy would not be significantly affected.

The Clean Energy Future plan

The Australian Governments Clean Energy Future plan is not expected to adversely affect power system

operations during the PSAs outlook period, given it includes a number of initiatives that are expected to assist the

transition.

For more information about the analysis and these results, see the AEMO website.3

Scenarios examined by the PSA

The 2012 PSA examines two scenarios and their power system impacts. The Expected scenario represents power

system outcomes AEMO considers to be the most likely. The Sensitivity scenario examines the potential impact of

withdrawing 1,000 MW of older generation distributed across the NEM. Table 1 provides a high-level comparison of

the scenario study results.

1 AEMO. Available http://www.aemo.com.au/en/Electricity/Forecasting/2012-National-Electricity-Forecasting-Report. Viewed 07 August 2012.2 AEMO. Available http://www.aemo.com.au/en/Electricity/Market-and-Power-Systems/Reserve-Management/Procedure-for-the-Exercise-of-

Reliability-and-Emergency-Reserve-Trader-RERT. Viewed 26 July 2012.3 Available http://www.aemo.com.au/Electricity/Market-and-Power-Systems/Power-System-Adequacy-Two-Year-Outlook.
http://www.aemo.com.au/en/Electricity/Market-and-Power-Systems/Reserve-Management/Procedure-for-the-Exercise-of-Reliability-and-Emergency-Reserve-Trader-RERThttp://www.aemo.com.au/en/Electricity/Market-and-Power-Systems/Reserve-Management/Procedure-for-the-Exercise-of-Reliability-and-Emergency-Reserve-Trader-RERThttp://www.aemo.com.au/en/Electricity/Market-and-Power-Systems/Reserve-Management/Procedure-for-the-Exercise-of-Reliability-and-Emergency-Reserve-Trader-RERThttp://www.aemo.com.au/en/Electricity/Market-and-Power-Systems/Reserve-Management/Procedure-for-the-Exercise-of-Reliability-and-Emergency-Reserve-Trader-RERThttp://www.aemo.com.au/en/Electricity/Market-and-Power-Systems/Reserve-Management/Procedure-for-the-Exercise-of-Reliability-and-Emergency-Reserve-Trader-RERT


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iv Executive summary AEMO 2012

Table 1 Scenario comparison

Assessment Expected scenario Sensitivity scenario

Reserve capacity

Minor shortfalls in South Australia in winter 2013.

These coincide with planned generator outages,and are insufficient to initiate Reliability andEmergency Reserve Trader (RERT) provisions.

Minor shortfalls in South Australia in winter 2013.These coincide with planned generator outages,and are insufficient to initiate RERT provisions.

Energy reserveAll regions fall within the 0.002% unserved energy(USE) Reliability Standard.

All regions fall within the 0.002% USE ReliabilityStandard.

Frequency control

For an interconnector trip4 during import, frequency

standards are maintained in every region exceptSouth Australia.

For an interconnector trip during export, frequencystandards are not maintained in Queensland, SouthAustralia, and Victoria and South Australia(combined).

For an interconnector trip during import, frequency

standards are maintained in every region exceptSouth Australia.

For an interconnector trip during export, frequencystandards are not maintained in Queensland, SouthAustralia, and Victoria and South Australia(combined).

Interconnectorcapability

Not expected to result in reliability or securityissues.

Not expected to result in reliability or securityissues.

Post contingencycontrol

Sufficient capability. Sufficient capability.

Voltage control

Reactive power reserves are adequate in everyregion except New South Wales.

Some voltage control issues are possible inTasmania and Victoria. Issues in New South Walesare diminishing.

Reactive power reserves are adequate in everyregion except New South Wales.

Some voltage control issues are possible inTasmania and Victoria. Issues in New South Walesare diminishing.

4 The interconnector trips are non-credile contingency events except for the trip of Basslink.


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AEMO 2012 Contents v

CONTENTS

EXECUTIVE SUMMARY III

TABLES VII

FIGURES VII

CHAPTER 1 - INTRODUCTION 1-1

CHAPTER 2 - EXPECTED SCENARIO RESULTS 2-1

2.1 Reserve capacity 2-1

2.2 Energy adequacy 2-22.3 Frequency control 2-2

2.4 Interconnector capability 2-6

2.5 Post-contingency control 2-7

2.6 Voltage control and reactive power reserves 2-8

CHAPTER 3 - SENSITIVITY SCENARIO RESULTS 3-1

3.1 Reserve capacity 3-1

3.2 Energy adequacy 3-1

3.3 Frequency control 3-2

3.4 Interconnector capability 3-43.5 Post-contingency control 3-4

3.6 Voltage control and reactive power reserves 3-4

CHAPTER 4 - REVIEW OF TRENDS 4-1

4.1 Constraint equations 4-1

4.2 Voltage excursions 4-1

4.3 Frequency excursions 4-2

CHAPTER 5 - INPUTS AND ASSUMPTIONS 5-1

5.1 Maximum demand projections 5-1

5.2 Demand-side participation and non-scheduled generation 5-2

5.3 Minimum reserve levels 5-3

5.4 Wind generation 5-3

5.5 Future projects and generation retirement 5-3


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vi Contents AEMO 2012

IMPORTANT NOTICE D1

LIST OF NTNDP ZONES M1

LIST OF MEASURES AND ABBREVIATIONS M3

Units of measure M3

Abbreviations M3

GLOSSARY G1


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AEMO 2012 Contents vii

TABLES

Table 2-1 Energy assessment (Expected scenario) 2-2Table 2-2 Frequency control assessment (Expected scenario) - high demand, high import 2-5Table 2-3 Frequency control assessment (Expected scenario) - low demand, high import 2-6Table 2-4 Frequency control assessment (Expected scenario) - high demand, high export 2-6Table 2-5 Frequency control assessment (Expected scenario) - low demand, high export 2-6Table 2-6 Likelihood of voltage control difficulties (Expected scenario) 2-8Table 2-7 Adequacy of reactive power reserves (Expected scenario) 2-9Table 2-8 Historical reactive power reserves under high wind, high demand conditions 2-9Table 2-9 Historical reactive power reserves under high wind, low demand conditions 2-10Table 3-1 Sensitivity scenario 3-1Table 3-2 Energy assessment (Sensitivity scenario) 3-2Table 3-3 Frequency control assessment (Sensitivity scenario) high demand, high import 3-2

Table 3-4 Frequency control assessment (Sensitivity scenario) low demand, high import 3-3Table 3-5 Frequency control assessment (Sensitivity scenario) high demand, high export 3-3Table 3-6 Frequency control assessment (Sensitivity scenario) low demand, high export 3-3Table 3-7 Likelihood of voltage control difficulties (Sensitivity scenario) 3-4Table 3-8 Adequacy of reactive power reserves (Sensitivity scenario) 3-5Table 4-1 Two-year analysis of interconnector constraint equation trends 4-1Table 5-1 Regional maximum demand projections (MW) 5-1Table 5-2 Interconnector capability and voltage control study low demand snapshots (MW) 5-1Table 5-3 Frequency control study demand cases (MW) 5-2Table 5-4 Regional demand-side participation and non-scheduled generation contribution (MW) 5-2Table 5-5 Minimum reserve levels (MW) 5-3

FIGURES

Figure 2-1 Tasmanian Fast Raise FCAS requirements as a function of system inertia 2-3Figure 4-1 Frequency excursions in the mainland regions by event type 4-2Figure 4-2 Frequency excursions in Tasmania by event type 4-3


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viii Contents AEMO 2012



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AEMO 2012 Introduction 1-1

CHAPTER 1 - INTRODUCTION

The 2012 Power System Adequacy (PSA) report assesses the electricity supply outlook for the next two years,complementing the 10-year outlook provided by the Electricity Statement of Opportunities (ESOO).

AEMO continuously monitors power system adequacy, and provides information to market participants on an

ongoing basis in accordance with the National Electricity Rules (for more information see the AEMO website5).

Scenarios and projections examined by the PSA

The 2012 PSA examines two scenarios and their power system impacts:

The Expected scenario represents the most likely power system outcomes, and is based on the most

probable forecasts and anticipated generation availability. The connection of wind farms recently classified as

advanced proposals6

and publicly announced proposals7

is also considered when there are potential power

system operation impacts.8

The Sensitivity scenario examines the potential impact of the withdrawal of 1,000 MW of older generationdistributed across the NEM.

Each scenario also considers component studies involving low and high wind generation.

The 2012 PSA treats the generation forecasts and demand projections used in its production as follows:

The generation capacity forecasts include all existing generation and committed new generation projects

based on information available as at July 2012. This includes recently advised reductions in the available

capacity of several coal-fired power stations. As the Australian Governments Contract for Closure

negotiations have been extended, the outcomes of this process could not be taken into account, given the

preferred timeframe for closure is beyond the PSAs outlook period.

The PSA considers demand for three separate studies involving regional maximum demand projections,

interconnector capability and voltage control study low demand snapshots, and frequency control study

demand cases.

The maximum demand projections are consistent with the 2012 National Electricity Forecast Report (NEFR),

and are based on a number of assumptions about the economy and government policy (including clean

energy policies). For more information about the demand projections, see Section 5.1.

Broad considerations involving power system operations include the following:

A downward pressure on load growth through higher electricity prices has the potential to improve reliability

(relative to the status quo).

The bid price arrangements for coal-fired generation will tend to make black coal generation more competitive

than brown coal, which may result in increased inter-regional power transfers from Queensland and New

South Wales to Victoria and South Australia, and increased gas powered generation (GPG) at the expense of

coal-fired generation. This is not expected to impact reliability or security during the PSAs outlook period.

5 AEMO. Available http://www.aemo.com.au/data/market_notices/MARKETNOTICEINDEX.shtm. Viewed 24 July 2012.6

Wind farms considered include those listed as advanced proposals with estimated commissioning dates prior to the end of June 2014, as listed on

AEMOs Generation Information web page in July 2012, at: http://www.aemo.com.au/Electricity/NEM-Data/Generation-Information.7 Wind farms considered include those listed as publicly announced proposals with estimated commissioning dates prior to the end of June 2015, as

listed on AEMOs Generation Information web page in July 2012, at: http://www.aemo.com.au/Electricity/NEM-Data/Generation-Information.8 Due to the limited availability of wind turbine modelling and network augmentation information, only the frequency control and post-contingency

control studies were able to be modelled accurately.
http://www.aemo.com.au/data/market_notices/MARKETNOTICEINDEX.shtmhttp://www.aemo.com.au/data/market_notices/MARKETNOTICEINDEX.shtm


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1-2 Introduction AEMO 2012

The Clean Energy Future plan

The Clean Energy Act was passed by the Australian Government on 8 November 2011. The Acts key instrument is

the carbon price (introduced on 1 July 2012), which aims to reduce carbon dioxide equivalent (CO2-e) emissions to

5% below year 2000 levels by 2020, and up to 25% with equivalent international action.9

Key features of the policy include the following:

The progressive introduction of a CO2-e price of $23, $24.15, and $25.40 per tonne each year for the first

three years (for business emitting more than 25 kilotonnes (KT) of CO2-e per annum), followed by an

internationally linked, floating price emissions trading scheme.

Assistance of $5.5 billion for a pool of generators10

over the first five years ($1 billion in the 201112 financial

year, followed by 41.7 million free carbon permits each financial year from 201314 to 201617). This

assistance is conditional on retaining market registration or seeking certification from AEMO that closure does

not threaten reliability for two years.11

Contracts for closure of up to 2,000 MW of coal-fired generation with emissions intensity above 1.2 tonnes of

CO2-e per megawatt hour (t CO2-e/MWh) by 2020. Eligible power stations are Playford, Hazelwood,

Yallourn, Collinsville and Energy Brix. The Government originally aimed to complete the process by 30 June2012

12but has since announced an indefinite extension to the negotiations.

13Before entering into contracts,

the Government will consider power system reliability based on advice from AEMO.

A Clean Energy Finance Corporation14

with access to $10 billion in investment capital over 10 years from

201314, for investment in renewable and low emissions energy and energy efficiency.

The Energy Security Council15

, which may refinance generator debt where it is unavailable or provide

assistance where the failure of financially distressed participants risks energy security.

The clean energy legislation does not affect the operation of the national Renewable Energy Target scheme, which

provides incentives for new renewable generation.

Clean Energy Future plan impacts on power system operations

The transition mechanisms involving conditional generator assistance and the Energy Security Council should

mitigate the risk of severe supply deterioration resulting from the implementation of the Clean Energy Future Plan

within the PSAs outlook period. Generators receiving assistance and seeking to withdraw capacity must seek

anticipatory certification from AEMO that power system reliability will remain within the Reliability Standard for two

years after the withdrawal.

The CO2-e price will have some impact on the relative short-run marginal costs of generators from 1 July 2012.

For example, it is expected that brown coal generators will face a marginal cost increase in the order of $30/MWh,

while a combined-cycle gas turbines (CCGT) will face a marginal cost increase of approximately $10/MWh. This

may mean that high emission generation will have more partial dispatch and standby periods than has historically

been the case. This does not necessarily adversely impact power system reliability or security over the outlook

period, as market signals will be expected to encourage all plant to perform during high demand periods. AEMO is

in discussions with the most affected generators concerning any changes in operational performance, and will

closely monitor issues as they arise.

9 Australian Government. Availablehttp://www.cleanenergyfuture.gov.au/.Viewed 24 July 2012.10 With an emissions intensity of over 1 tonne of CO2-e per megawatt hour (t CO2-e/MWh) as-generated, and capped for generators emitting more

than 1.3t CO2-e/MWh. For more information about payments, seehttp://www.climatechange.gov.au/government/initiatives/energy-security-fund-

cash-payments/eligible.aspx.11 AEMO. Available http://www.aemo.com.au/anticipatory_certification/anticipatory_certification.html. Viewed 24 July 2012.12

Australian Government. Available http://www.ret.gov.au/Department/Documents/clean-energy-

future/CONTRACT_FOR_CLOSURE_FACT_SHEET_FINAL.PDF. Viewed 24 July 2012.13 Australian Government. Available http://minister.ret.gov.au/MediaCentre/MediaReleases/Pages/ContractClosureNegotiationsExtended.aspx.

Viewed 24 July 2012.14

CEFC. Available http://www.cefcexpertreview.gov.au/content/Content.aspx?doc=home.htm. Viewed 24 July 2012.15

ESC.Availablehttp://www.energysecuritycouncil.gov.au/content/Content.aspx?doc=home.htm. Viewed 24 July 2012.
http://www.cleanenergyfuture.gov.au/http://www.cleanenergyfuture.gov.au/http://www.climatechange.gov.au/government/initiatives/energy-security-fund-cash-payments/eligible.aspxhttp://www.climatechange.gov.au/government/initiatives/energy-security-fund-cash-payments/eligible.aspxhttp://www.climatechange.gov.au/government/initiatives/energy-security-fund-cash-payments/eligible.aspxhttp://www.aemo.com.au/anticipatory_certification/anticipatory_certification.htmlhttp://www.ret.gov.au/Department/Documents/clean-energy-future/CONTRACT_FOR_CLOSURE_FACT_SHEET_FINAL.PDFhttp://www.ret.gov.au/Department/Documents/clean-energy-future/CONTRACT_FOR_CLOSURE_FACT_SHEET_FINAL.PDFhttp://minister.ret.gov.au/MediaCentre/MediaReleases/Pages/ContractClosureNegotiationsExtended.aspxhttp://www.cefcexpertreview.gov.au/content/Content.aspx?doc=home.htmhttp://www.cefcexpertreview.gov.au/content/Content.aspx?doc=home.htmhttp://www.energysecuritycouncil.gov.au/content/Content.aspx?doc=home.htmhttp://www.energysecuritycouncil.gov.au/content/Content.aspx?doc=home.htmhttp://www.energysecuritycouncil.gov.au/content/Content.aspx?doc=home.htmhttp://www.energysecuritycouncil.gov.au/content/Content.aspx?doc=home.htmhttp://www.cefcexpertreview.gov.au/content/Content.aspx?doc=home.htmhttp://minister.ret.gov.au/MediaCentre/MediaReleases/Pages/ContractClosureNegotiationsExtended.aspxhttp://www.ret.gov.au/Department/Documents/clean-energy-future/CONTRACT_FOR_CLOSURE_FACT_SHEET_FINAL.PDFhttp://www.ret.gov.au/Department/Documents/clean-energy-future/CONTRACT_FOR_CLOSURE_FACT_SHEET_FINAL.PDFhttp://www.aemo.com.au/anticipatory_certification/anticipatory_certification.htmlhttp://www.climatechange.gov.au/government/initiatives/energy-security-fund-cash-payments/eligible.aspxhttp://www.climatechange.gov.au/government/initiatives/energy-security-fund-cash-payments/eligible.aspxhttp://www.cleanenergyfuture.gov.au/


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AEMO 2012 Expected scenario results 2-1

CHAPTER 2 - EXPECTED SCENARIO RESULTS

This chapter presents the two-year power system operational capacity assessment under the Expected scenario.Based on anticipated generation and maximum demand, this assessment informs AEMOs decisions regarding the

need to intervene to obtain additional generation, demand-side capacity, or ancillary services. It also provides an

assessment of power system adequacy in the following areas:

Reserve capacity.

Energy adequacy.

Frequency control.

Interconnector capability.

Post-contingency control.

Voltage control and reactive power reserves.

Where relevant, the power system adequacy criteria have been assessed against high (maximum demand) andlow demand scenarios

16as well as high and low wind generation scenarios.

17Some studies also assume the

accelerated commissioning of wind generation.

The maximum demand projections used in the assessment were published by AEMO in late June 2012. Unless

noted otherwise, the generation capacities have been provided by the generators via the Medium-term Projected

Assessment of System Adequacy (MT PASA).

For more information about the assessments inputs and assumptions, see Chapter 5.

2.1 Reserve capacity

The reserve capacity assessment indicates no reserve capacity shortfalls are projected for 201213 under the

Expected scenario. A maximum reserve capacity shortfall of 52 MW is forecast for South Australia for three days in201314.

18This is due to concurrent planned outages of a number of South Australian generating units, and AEMO

will liaise with the relevant generators to address these shortfalls.

Assessment approach

The reserve capacity assessment compares the amount of supply available within each region with the two-year

outlooks expected 10% probability of exceedence (POE) maximum demand projection. The regions minimum

reserve level (MRL) is taken into account to ensure unserved energy (USE) does not exceed 0.002% of annual

energy while allowing for the unexpected loss of generation.

In accordance with National Electricity Rules (NER) obligations, AEMO assesses the adequacy of the reserve

capacity to meet potential maximum demand outlook using MT PASA19

, which is published weekly.20

Where a reserve capacity shortfall is indicated, AEMO ensures generators are given the opportunity to revisegeneration availability forecasts. If the forecast reserve capacity shortfall persists, AEMO will consider commencing

the RERT tender process.21

16The high maximum demand projection applies a 10% probability of exceedence (POE) projection. Low maximum demand projections are based

on historical demand. For more information, see Section 5.1.17 For more information on the assumptions of high and low levels of wind generation used for all studies, see Section 5.4.18 Results are based on the 3 July 2012 MT PASA assessment.19 For more information about MT PASA requirements, see NER clause 3.7.2.20 AEMO. Available http://www.aemo.com.au/Electricity/NEM-Data/Outlook-PASA-Data. Viewed 24 July 2012.


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2-2 Expected scenario results AEMO 2012

2.2 Energy adequacy

The energy adequacy assessment indicates that sufficient energy should be available to ensure that USE in every

region will be lower than the 0.002% Reliability Standard set by the Reliability Panel.

Table 2-1 provides a high level summary of the results from the Energy Adequacy Assessment Projection (EAAP)

analysis performed by AEMO. These results assume short-term average rainfall22

.

Table 2-1 Energy assessment (Expected scenario)

Regiona

201213 201314

Average USEhours

b

Total USE(MWh)

% Annual USEAverage USE

hoursb

Total USE(MWh)

% Annual USE

Queensland - - 0.0000% - - 0.0000%

New SouthWales

- - 0.0000% - - 0.0000%

Victoria - 101 0.0002% - 92 0.0002%

South Australia - 20 0.0002% - 25 0.0002%

Tasmania - - 0.0000% - - 0.0000%

a. These results marginally differ from the EAAP assessment results published on 30 June 2012 due to updated demand forecasts.

b. These are the forecast hours of USE, determined by averaging the results from the EAAP analysis simulations.

Assessment approach

The energy adequacy assessment considers each regions energy and maximum demand projections, and

restrictions to the amount of energy scheduled generating units can provide due to a range of factors including fuel

shortages, cooling water restrictions, and environmental limits. This information is provided by scheduledgenerators, and published in the EAAP each quarter.

23

The energy adequacy assessment differs from the reserve capacity assessment in the following ways:

Reserve capacity assessments are carried out by considering a regions supply-demand outlook at a specific

point in time.

Energy assessments are more complex as the energy available from an energy-limited generating system

can be scheduled at any time, but once used, the energy is no longer available.

The question of when to utilise the energy from a range of energy-limited generating systems is complex, and

is managed by AEMO by using probabilistic modelling techniques to determine the amount of USE that is

considered likely to occur within each region.

2.3 Frequency control

Results from the frequency control assessment indicate that the frequency operating standards will be maintained

for all regional separation cases at high import except for the separation of South Australia with low demand and

21 AEMO. Available http://www.aemo.com.au/en/Electricity/Market-and-Power-Systems/Reserve-Management/Procedure-for-the-Exercise-of-

Reliability-and-Emergency-Reserve-Trader-RERT. Viewed 24 July 2012.22 Short term average rainfall scenario is based on the average rainfall recorded over the past 10 years.23 AEMO. Available http://www.aemo.com.au/en/Electricity/Market-and-Power-Systems/Energy-Adequacy-Assessment-Projection. Viewed 24 July

2012.
http://www.aemo.com.au/en/Electricity/Market-and-Power-Systems/Reserve-Management/Procedure-for-the-Exercise-of-Reliability-and-Emergency-Reserve-Trader-RERThttp://www.aemo.com.au/en/Electricity/Market-and-Power-Systems/Reserve-Management/Procedure-for-the-Exercise-of-Reliability-and-Emergency-Reserve-Trader-RERThttp://www.aemo.com.au/en/Electricity/Market-and-Power-Systems/Reserve-Management/Procedure-for-the-Exercise-of-Reliability-and-Emergency-Reserve-Trader-RERThttp://www.aemo.com.au/en/Electricity/Market-and-Power-Systems/Reserve-Management/Procedure-for-the-Exercise-of-Reliability-and-Emergency-Reserve-Trader-RERT


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high wind generation. The operating standards may not be maintained for separation events during a range of high

export cases.

AEMO has started designing over-frequency generator trip schemes for Queensland and South Australia to

manage the separation of these regions during high export periods. AEMO is also assessing options to ensure the

frequency in South Australia remains within the frequency operating standards following a separation event during

periods of low demand and high import.

Tasmanian frequency control ancillary service requirements

In determining local frequency control ancillary service (FCAS) requirements in Tasmania, AEMO considers the

power system frequency and power system inertia impacts from losing the largest generating unit, load block, and

the Basslink interconnector. When there are few generating units synchronised, the Raise and Lower FCAS

requirements increase to compensate for the low system inertia. Due to the relatively high power system inertia in

interconnected mainland regions, the local FCAS requirement calculations for the mainland are independent of

power system inertia.

Expected FCAS requirements were studied using historical Tasmanian power system inertia observed over the last

two years. The FCAS most affected by low system inertia involves Fast Raise FCAS.

Figure 2-1 shows the Tasmanian Fast Raise FCAS requirements as a function of power system inertia taking into

account the connection of Musselroe Wind Farm. The graph demonstrates that the requirement for the loss of the

largest generating unit (144 MW) may be as high as 200 MW at times of low inertia. Currently, 358 MW of Fast

Raise FCAS is registered in Tasmania, making a shortage unlikely within the next two years.

Figure 2-1 Tasmanian Fast Raise FCAS requirements as a function of system inertia

AEMO is currently investigating impact of the increased FCAS requirements and the method of meeting these

requirements.

0

55

110

165

220

3500 4500 5500 6500 7500 8500 9500 10500 11500

TasmanianFastFCAS

Required

Inertia (MWs)

Fast Raise FCAS - High Demand Fast Raise FCAS - Low Demand

Fast Lower FCAS - High Demand Fast Lower FCAS - Low Demand


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Background information

Power system frequency provides a measure of the balance between the instantaneous electrical power output

from generation and electrical power consumption. Without this balance, power system frequency will fluctuate. To

ensure electrical equipment operates safely and correctly, the power system should operate at a nominal frequency

close to 50 cycles per second.

AEMO purchases a range of FCAS24

from market participants to enable adequate power system frequency control,

which includes regulating services for normal operating conditions, and contingency services for a fast response

following contingency events (such as the loss of a generating unit).

Although it is not normally regarded as a credible risk, the power system has previously been severed at an

interconnection point, resulting in two electrically-separated networks.25

When this occurs, operational issues

within each network involve the following factors:

Power system frequency, which should remain within acceptable limits as set by the Reliability Panelsfrequency operating standard.

Power system inertia, which is a measure of the rotating mass of generating units and electrical motors

operating at any given point in time. A higher inertia results in less susceptibility to frequency variations due tosudden disturbances.

Power system inertia tends to decrease as wind generation displaces existing generation (which has greater

inertia). Due to the significant number of wind farms operating in the NEM, overall system inertia decreases at

times of high wind generation. With the large number of committed wind farm projects, a large reduction in system

inertia potentially has implications for power system operations within the frequency operating standard.

Power system inertia in regions other than South Australia and Tasmania is considered unlikely to change

significantly over the next two years based on current committed projects.

Assessment approach

Based on the power systems recent operational history, the points in the network where separation events are

likely to result in the largest frequency disturbances26

are as follows:

Loss of the VictoriaSouth Australia AC interconnector due to a non-credible contingency event causing South

Australia to become separated from the rest of the NEM.

Loss of the VictoriaNew South Wales AC interconnector due to a non-credible contingency event causingVictoria and South Australia to become separated from the rest of the NEM.

Loss of the New South WalesQueensland AC interconnector due to a non-credible contingency eventcausing Queensland to become separated from the rest of the NEM.

Loss of the TasmaniaVictoria DC interconnector due to a credible contingency event causing Tasmania to

become separated from the rest of the NEM.

Table 2-2 to Table 2-5 summarise a series of studies involving electrical-separation scenarios for a range of system

condition simulation cases:

High demand, high import. Low demand, high import.

High demand, high export.

Low demand, high export.

24AEMO. Available http://www.aemo.com.au/en/Electricity/Market-and-Power-Systems/Ancillary-Services/Market-Ancillary-Service-Specification.

Viewed 26 July 2012.25 The separation of Tasmania from the mainland regions involves the loss of a single transmission element and is, therefore, considered a credible

contingency event.26 Frequency operating standards for the separation event has been used in analysing the loss of the TasmaniaVictoria DC interconnector. The

other separation events have been analysed using the frequency operating standards for the multiple contingency event.
http://www.aemo.com.au/en/Electricity/Market-and-Power-Systems/Ancillary-Services/Market-Ancillary-Service-Specificationhttp://www.aemo.com.au/en/Electricity/Market-and-Power-Systems/Ancillary-Services/Market-Ancillary-Service-Specification


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For each of these system conditions, three scenarios for wind generation were considered:

All existing and committed wind farms are available and operating at low output due to low wind conditions

(low wind generation).

All existing and committed wind farms are available and operating at high output due to high wind conditions(high wind generation).

27

All existing and committed wind farms are available and operating at high output due to high wind conditions.

It is also assumed that wind farms recently classified as advanced proposals28

or publicly announced

proposals29

are commissioned early and are operating at high output.

Additional wind generation capacity displacing conventional generation based on merit order is also assumed,

which reflects the impact of a carbon price from 1 July 2012.

Table 2-2 Frequency control assessment (Expected scenario) - high demand, high import

Regionseparated

Low wind generation High wind generationHigh wind generation withadvanced proposals and

publicly announced proposals

Frequencyoperatingstandard

Loadshedding


Loadshedding


Loadshedding

Queensland Maintained. No. Maintained. No. Maintained. No.

South Australia Maintained. Likely. Maintained. Likely. Maintained. Likely.

South Australiaand Victoria

Maintained. Likely. Maintained. Likely. Maintained. Likely.

Tasmania Maintained. Likely. Maintained. Likely. Maintained. Likely.

27High wind generation for the South Australian separation event may be constrained by the requirement for a minimum number of synchronous

units with power system stabilizers in service in South Australia as per limit advice received from ElectraNet at the time the studies were conducted

(which has since been updated). High wind generation for a Tasmanian separation event may be constrained by the minimum fault level

requirement in Tasmania to avoid inverter commutation instability.28 See note 2.29 See note 3.


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Table 2-3 Frequency control assessment (Expected scenario) - low demand, high import

Regionseparated




Loadshedding


Loadshedding


Loadshedding


South Australia Maintained. Likely. Breached. Likely. Breached. Likely.




Table 2-4

Frequency control assessment (Expected scenario) - high demand, high export

Regionseparated




Generationtripping


Generationtripping


Generationtripping

Queensland Maintained. Likely. Maintained. Likely. Maintained. Likely.



Maintained. Likely. Breached. Likely. Breached. Likely.


Table 2-5 Frequency control assessment (Expected scenario) - low demand, high export

Regionseparated




Generationtripping


Generationtripping


Generationtripping

Queensland Breached. Likely. Breached. Likely. Breached. Likely.

South Australia Breached. Likely. Breached. Likely. Breached. Likely.


Breached. Likely. Breached. Likely. Breached. Likely.


2.4 Interconnector capability

Results from the interconnector capability assessment indicate that increased wind generation is not expected to

adversely impact interconnector power transfer limits over the next two years. In some circumstances, increased

wind generation increases interconnector power transfer capability.


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Only high-level modelling of the newly committed Musselroe Wind Farm was used for the studies as detailed

information was not available at the time.

Assessment approach

An important power system adequacy measure involves power transfers between regions because of their impacton power supply reliability. AEMO reviewed recent interconnector power flow trends to identify interconnectors

operating at or near their limits, or trending towards these limits (for a summary of the results of this trend analysis

see Chapter 4).

Analysis undertaken to determine how these limits might be impacted by increased wind generation assumed the

following:

The transient and voltage stability power system contingencies that have been setting regional export and

import limits for the past two years will continue for the next two years.

Additional wind generation capacity displaces conventional generation based on a merit order that reflects the

impact of the carbon price from 1 July 2012.

2.5 Post-contingency control

Results from the post-contingency control assessment indicate that for the range of conditions examined, the

power system has sufficient capacity to recover to a secure operating state within 30 minutes of a credible

contingency event occurring, or a sudden reduction in regional wind generation.30

Assessment approach

The power system is operated to withstand any single credible contingency event without exceeding operating

limits (referred to as a secure operating state), and must be able to be returned to a secure operating state within

30 minutes, so that it can again withstand a subsequent contingency event. The ability to achieve these

requirements depends on changing the output of scheduled generation at an adequate rate.

While the most onerous contingency event is the loss of the largest generating unit in a region, a reduction in windgeneration due to sudden changes in wind speed has also been considered. Normally, a contingency event like

this is managed to some extent through changes in interconnector power flows. To simulate the worst case,

however, assessments have assumed no interconnector support from other regions.

In every region other than South Australia, the loss of the largest generating unit represents the critical credible

contingency event. In South Australia, the most critical credible contingency event is a change in wind generation

over a 5-minute or 30-minute period of approximately 290 MW and 310 MW, respectively. This exceeds the largest

generating unit in South Australia (270 MW).

30 High wind generation under the low demand scenario for South Australia is constrained by the requirement for a minimum number of synchronous

units with power system stabilizers in service in South Australia as per limit advice received from ElectraNet at the time the studies were conducted

(which has since been updated).


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Wind generation has limited ability to control power output in response to a contingency event. Generally, as the

amount of power supplied by wind generation increases, the power systems post contingency response capability

may degrade should this result in other generating units being switched off. To examine this, both high and low

wind generation scenarios have been studied in every region.

It is assumed that additional wind generation capacity displaces conventional generation based on a merit order

that reflects the impacts of the carbon price from 1 July 2012.

The studies indicate that every region has sufficiently high rate of change31

to maintain a secure operating state

following the loss of the largest generating unit or the largest wind generation variation.

2.6 Voltage control and reactive power reserves

Voltage control assessment

AEMO regularly monitors transmission network voltage levels and notes significant voltage fluctuations or trends

that may warrant closer examination, and whether there will be future voltage control issues.

Results from the voltage control assessment indicate that in the areas examined (see Table 2-6), voltage control isnot expected to deteriorate significantly over the next two years. Some issues are likely to be resolved by

transmission network reinforcements. No issue is l ikely to be made worse by increased wind generation capacity.

Voltage control issues experienced at Georgetown relate to the operation of the Basslink interconnector, and

Transend Networks and National Grid Australia are addressing this issue.

Table 2-6 summarises the analysis of locations where voltage fluctuations have previously occurred, and assesses

their likelihood under high and low demand conditions for different levels of wind generation.

Table 2-6 Likelihood of voltage control difficulties (Expected scenario)

Location

High demanda

Low demanda

High windgeneration

Low windgeneration

High windgeneration

Low windgeneration

Beaconsfield West, New SouthWales

Diminishing. Diminishing. Diminishing. Diminishing.

Moorabool, Victoriab Possible. Possible. Possible. Possible.

Georgetown, Tasmaniac - - Likely. Likely.

Gordon, Tasmaniad Possible. Possible. Possible. Possible.

a. Diminishing means that committed network augmentations in and around Beaconsfield West are likely to improve voltage control issues in that

area. Possible means that no committed network augmentations are likely to significantly improve voltage control in the relevant area and

voltage control issues may occur infrequently. Likely means that no committed network augmentations are likely to significantly improve

voltage control in the relevant area and voltage control issues are likely to occur frequently.

b. The overvoltage issues at the 500 kV Moorabool Terminal Station were marginal and infrequent, and do not materially impact voltage control.

c. The voltage violations at Georgetown were only observed during low demand periods.

d. The overvoltage issues at the Gordon 220 kV bus were marginal and infrequent, and do not materially impact voltage control.

Adequacy of reactive power reserves for 201314

To ensure sufficient reactive power reserves, AEMO procures reactive power ancillary services (RPAS) where

there are possible deficiencies, and each year publishes a requirement for RPAS in the NTNDP.

31 Regionally aggregated rate of change of active power of scheduled generation (expressed as MW/minute).


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Insufficient reactive power reserves were observed in the New South Wales 330 kV transmission system between

Kangaroo Valley and Upper Tumut under low demand conditions when Snowy generation, and the Tallawarra,

Kangaroo Valley and Bendeela Power Stations are out of service.

Table 2-7 lists the assessment of current reactive power reserves under high wind scenarios for the next two years.

Table 2-7 Adequacy of reactive power reserves (Expected scenario)

RegionHigh wind

a

High demand Low demand

Queenslandb Adequate. Adequate.

New South Wales Adequate. Inadequate.c

Victoria Adequate. Adequate.

South Australia Adequate. Adequate.

Tasmaniad

Adequate. Adequate.

a. These outcomes are based on studies conducted using base study cases used in the 2011 NTNDP with regional demands scaled to the 2012

NEFR for 201314 (for a detailed list of assumptions, see Chapter 5). Increasing levels of wind penetration are not expected to significantly

change regional reactive power requirements in the period leading up to July 2014. For information about the 2012 NEFR see the AEMO

website. Available http://www.aemo.com.au/en/ Electricity/Forecasting. Viewed 24 July 2012.

b. Wind generation has no material impact on the reactive reserves in Queensland due to the very low level of wind generation installed.

c. There is insufficient reactive reserve (absorbing capability) in the New South Wales 330 kV transmission network between Kangaroo Valley and

Upper Tumut during low demand periods. This is determined under the assumption that Snowy generation, and the Tallawarra, Kangaroo

Valley and Bendeela Power Stations are all out of service when the contingency occurs. AEMO has entered into a contract for RPAS to meet

the reactive power reserve requirements in New South Wales during light load periods.

d. The newly committed Musselroe wind farm was not modelled due to insufficient information when the studies were conducted.

Background information

Power system voltage stability maintenance requires adequate reserves of reactive power. In areas with insufficient

reactive power reserves, voltage collapse may occur following a major contingency event.

Table 2-8 and Table 2-9 summarise the historical reactive power reserves for each National Transmission Network

Development Plan (NTNDP) zone under high wind, high demand and high wind, low demand scenarios. Each

scenario is based on a single historical snapshot that most suitably represents the scenario.

Table 2-8 Historical reactive power reserves under high wind, high demand conditions

Region Zonea

High wind, high demand

Generationb

SVCc

Capacitorc Reactorc

SurplusMVAr exportcapability as% installed

SurplusMVAr importcapability as% installed




SurplusMVAr import

capabilityas %

installed

Queensland

NQ 95% 96% 98% 84% 86% 59%

CQ 90% 81% -d -d 58% 74%

SEQ 79% 100% 100% 79% 79% -d

SWQ 72% 100% 92% 100% 100% 86%

New South NNS 47% 100% 100% 98% 97% 50%
http://www.aemo.com.au/en/%20Electricity/Forecastinghttp://www.aemo.com.au/en/%20Electricity/Forecasting


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Region Zonea

High wind, high demand

Generationb

SVCc

Capacitorc Reactorc

Surplus

MVAr exportcapability as% installed

Surplus

MVAr importcapability as% installed

Surplus


Surplus


Surplus


Surplus

MVAr importcapabilityas %

installed

Wales NCEN 90% 97% 82% 100% 55% 68%

CAN -d -d -d -d 43% -d

SWNSW 96% 84% -d -d 100% 21%

Victoria

NVIC 100% 99% -d

-d

100% -d

LV 71% 100% -d -d 40% 100%

MEL 99% 99% 100% 89% 44% 24%

CVIC 92% 74% 88% 100% 52% -d

Tasmania TAS 75% 98% -d -d 45% -d

SouthAustralia

SESA 100% 100% 100% 0% 62% 100%

ADE 88% 96% 100% 74% 79% 50%

NSA 81% 100% -d -d 100% 55%

a. For a full description of each zone see the list of NTNDP zones.

b. As measured at the generator terminals.

c. All devices at or above 132 kV were included in the study.

d. There are no generators or reactive network devices installed in these zones.

Table 2-9 Historical reactive power reserves under high wind, low demand conditions

Region Zonea

High wind, low demand

Generationb

SVCc

Capacitorc Reactorc







Queensland

NQ 100% 98% 97% 83% 99% 52%

CQ 93% 81% -d -d 69% 68%

SEQ 100% 79% 100% 55% 100% -d

SWQ 100% 78% 100% 63% 100% 56%

New SouthWales

NNS 83% 69% 25% 100% 97% 17%

NCEN 96% 92% 100% 48% 91% 14%

CAN -d

-d

-d

-d

100% -d

SWNSW 100% 70% -d -d 100% 21%

VictoriaNVIC 100% 99% -d -d 68% -d

LV 86% 96% -d -d 40% 67%


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Region Zonea

High wind, low demand

Generationb

SVCc

Capacitorc Reactorc

Surplus


Surplus


Surplus


Surplus


Surplus


Surplus


MEL 100% 100% 100% 83% 100% 43%

CVIC 90% 59% 100% 59% 52% -d

Tasmania TAS 92% 96% -d -d 86% -d

SouthAustralia

SESA 100% 100% 100% 33% 100% -d

ADE 99% 88% 100% 51% 88% -d

NSA 100% 87% -d -d 100% 53%

a. For a full description of each zone see the list of NTNDP zones.

b. As measured at the generator terminals.

c. All devices at or above 132 kV were included in the study.

d. There are no generators or reactive network devices installed in these zones.


22/44





23/44

AEMO 2012 Sensitivity scenario results 3-1

CHAPTER 3 - SENSITIVITY SCENARIO RESULTS

The 2012 PSA Sensitivity scenario examines the potential impact of the unplanned, NEM-wide withdrawal of older

generation totalling 1,000 MW from 1 July 2012 onwards.

Table 3-1 lists the hypothetical generation withdrawals in each region. This scenario is intended purely as a

sensitivity study to examine the potential for certain key measures to cause issues with power system adequacy,

and no representation is made as to the actual likelihood of this scenario occurring.

Table 3-1 Sensitivity scenario

RegionGeneration capacity withdrawn on

1 July 2012

Queensland 205 MW

New South Wales 500 MW

Victoria 200 MW

South Australia 60 MW

Tasmania 35 MW

TOTAL 1,000 MW

3.1 Reserve capacity

The reserve capacity assessment indicates the forecast reserve capacity will meet the reliability requirements in

every region in 201213, despite the withdrawal of 1,000 MW of older generation.

No reserve capacity shortfalls are forecast for 201213. A maximum reserve capacity shortfall of 142 MW is

projected for South Australia for 12 days in 201314. This is due to concurrent planned outages of a number of

South Australian generating units. The withdrawal of generation totalling 60 MW in South Australia and 200 MW in

Victoria has also contributed to the increase in periods where the MRLs are not met.

If this scenario eventuates, AEMO will ensure generators are given the opportunity to revise generation availability

forecasts. If the forecast reserve capacity shortfall persists, AEMO will consider commencing the RERT tender

process.

Assessment approach

The Sensitivity scenario reserve capacity assessment uses MT PASA (for more information, Section 2.1), with

modified inputs to reflect the scenarios conditions. This scenario is an indication of what might occur underdifferent circumstances, and is not used as part of the RERT tender process.

3.2 Energy adequacy

The energy adequacy assessment indicates that the withdrawal of 1,000 MW of older generation results in an

increase in the potential amount of USE, but does not exceed the 0.002% Reliability Standard in any region.

Assessment approach

Table 3-2 lists the results of the assessment for short-term average rainfall. The Sensitivity scenario assessment

uses the EAAP (for more information, see Section 2.2), with modified inputs to reflect the scenarios conditions.


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3-2 Sensitivity scenario results AEMO 2012

Table 3-2 Energy assessment (Sensitivity scenario)

Region

201213 201314

Average USEhoursa

Total USE(MWh)

% annual

unservedenergy

Average USEhoursa

Total USE(MWh)

% annual

unservedenergy

Queensland - - 0.0000% - - 0.0000%

New SouthWales

- - 0.0000% - - 0.0000%

Victoria 1 215 0.0004% 1 184 0.0004%

South Australia 1 44 0.0004% 1 47 0.0004%

Tasmania - - 0.0000% - - 0.0000%

a. These are the forecast hours of USE determined by averaging the results from the EAAP analysis simulations.

3.3 Frequency control

The frequency control assessment indicates that while retiring 1,000 MW of older generation causes a material

reduction in power system inertia, the effect is not significant enough to substantially change power system

frequency performance. The results suggest the following:

The frequency operating standards will be maintained for all high import cases except for the South Australian

separation cases with low demand and high wind generation.

The frequency operating standards may not be maintained for a range of high export cases.

AEMO has commenced designing over-frequency generator trip schemes for Queensland and South Australia to

manage the separation of these regions during high export periods. AEMO is also assessing options to ensure the

South Australian frequency remains within the frequency operating standards following a separation event duringperiods of low demand and high import. AEMO believes these mitigating actions will address the frequency control

issues identified in the Sensitivity scenario.

Assessment approach

The frequency control adequacy assessment for the Sensitivity scenario uses the same approach as described in

Section 2.3, with modified inputs to reflect the scenarios conditions.

Table 3-3 to Table 3-6 summarise the results of this assessment.

Table 3-3 Frequency control assessment (Sensitivity scenario) high demand, high import

Region

separated




Loadshedding


Loadshedding


Loadshedding







25/44


Table 3-4 Frequency control assessment (Sensitivity scenario) low demand, high import

Regionseparated




Loadshedding


Loadshedding


Loadshedding


South Australia Maintained. Likely. Breached. Likely. Breached. Likely.




Table 3-5

Frequency control assessment (Sensitivity scenario)

high demand, high export

Regionseparated




Generationtripping


Generationtripping


Generationtripping

Queensland Maintained. Likely. Maintained. Likely. Maintained. Likely.



Maintained. Likely. Breached. Likely. Breached. Likely.


Table 3-6 Frequency control assessment (Sensitivity scenario) low demand, high export

Regionseparated




Generationtripping


Generationtripping


Generationtripping

Queensland Breached. Likely. Breached Likely. Breached Likely.

South Australia Breached. Likely. Breached. Likely. Breached. Likely.


Breached. Likely. Breached. Likely. Breached. Likely.



26/44



3.4 Interconnector capabilityThe interconnector capability assessment indicates that the withdrawal of 1,000 MW of older generation is notexpected to adversely impact interconnector power transfer limits over the next two years.

Assessment approach

The interconnector capability assessment for the Sensitivity scenario considered the capability of theinterconnectors described in Section 2.4 to determine the impact from withdrawing 1,000 MW of older generation.

The studies indicate that this level of withdrawal coupled with the current level of wind generation does not impactthe power transfer capability of any of the interconnectors over the next two years.

Only high-level modelling of the newly committed Musselroe Wind Farm was used for the studies as detailedinformation was not available at the time.

3.5 Post-contingency controlThe post-contingency control assessment indicates that despite the retirement of 1,000 MW of older generation,

the power system still retains sufficient capability to return to a secure operating state within 30 minutes of acredible contingency event, and every region has sufficiently high rate of change to maintain a secure operatingstate following the loss of the largest generating unit or the largest wind generation variation.

Assessment approach

The assessment for the Sensitivity scenario examined the same contingency events as described in Section 2.5.

3.6 Voltage control and reactive power reserves

The voltage control assessment indicates that the retirement of generation in relevant regions may not cause

significant voltage level management issues at the assessed locations.

Voltage control assessment

The voltage control capability assessment for the Sensitivity scenario examined the same locations as described inSection 2.6.

Table 3-7 summarises the results of this assessment.

Table 3-7 Likelihood of voltage control difficulties (Sensitivity scenario)

Location

High demanda Low demand

a

High windgeneration

Low wind generationHigh windgeneration

Low windgeneration

Beaconsfield West, NewSouth Wales

Diminishing. Diminishing. Diminishing. Diminishing.

Moorabool, Victoriab Possible. Possible. Possible. Possible.

Georgetown, Tasmaniac - - Likely. Likely.

Gordon, Tasmaniad Possible. Possible. Possible. Possible.

a. Diminishing means that committed network augmentations in and around Beaconsfield West are likely to improve voltage control issues in

that area. Possible means that no committed network augmentations are likely to significantly improve voltage control in the relevant area and

voltage control issues may occur infrequently. Likely means that no committed network augmentations are likely to significantly improve

voltage control in the relevant area and voltage control issues are likely to occur frequently.

b. The overvoltage issues at the 500 kV Moorabool Terminal Station were marginal and infrequent, and do not materially impact voltage control.

c. The voltage violations at Georgetown were only observed during low demand periods.

d. The overvoltage issues at the Gordon 220 kV bus were marginal and infrequent, and do not materially impact voltage control.


27/44


Reactive power reserves

The reactive power reserve adequacy assessment for the Sensitivity scenario examined the same locations asdescribed in Section 2.6.

Table 3-8 summarises the results of this assessment.

Table 3-8 Adequacy of reactive power reserves (Sensitivity scenario)

RegionHigh wind

a

High demand Low demand

Queenslandb Adequate. Adequate

New South Wales Adequate. Inadequate.c

Victoria Adequate. Adequate.

South Australia Adequate. Adequate.

Tasmaniad

Adequate. Adequate.

a. These outcomes are based on the studies conducted using the 2011 NTNDP base cases with regional demands scaled to the 2012 NEFR

projection for 201314 ( for a detailed list of assumptions see Chapter 5). Increasing levels of wind penetration are not expected to significantly

change regional reactive power requirements in the period leading up to July 2014.

b. Wind generation has no material impact on the reactive power reserves in Queensland due to the very low level of wind generation installed.

c. There is insufficient reactive reserve (absorbing capability) in the New South Wales 330 kV transmission network between Kangaroo Valley and

Upper Tumut during low demand periods. This is determined under the assumption that Snowy generation, and the Tallawarra, Kangaroo

Valley and Bendeela Power Stations are all out of service when a contingency occurs. AEMO has entered into a contract for RPAS to meet the

reactive power reserve requirements in New South W ales during light load periods.

d. The newly committed Musselroe wind farm was not modelled due to insufficient information when the studies were conducted.


28/44





29/44

AEMO 2012 Review of trends 4-1

CHAPTER 4 - REVIEW OF TRENDS

A review of system performance over the last two years has established the system performance parametersconsidered most likely to impact power system capabilities over the next two years. They are:

The duration and extent of interconnector constraint equations binding (reaching a limit) or violating

(exceeding a limit).

Voltage excursions and limit violations.

Frequency excursions and limit violations.

4.1 Constraint equations

Table 4-1 lists the high level trends from an examination of interconnector constraint equation behaviour. For more

information about these constraint equation trends see the PSA appendix.

Table 4-1 Two-year analysis of interconnector constraint equation trends

Interconnector Trend

New South WalesQueensland (QNI)

Slightly decreasing trend to being constrained on import to New South Wales. QNI bound mainlyin the direction of import to New South Wales.

New South WalesQueensland (Terranora)

Slightly decreasing trend to being constrained on import to New South Wales. Terranora boundmainly in the direction of import to New South Wales.

VictoriaNew South WalesSlightly decreasing trend to being constrained on both import to Victoria and export to New SouthWales. VictoriaNew South Wales bound mainly in the direction of export to New South Wales.

VictoriaSouth Australia

(Heywood)

Slightly decreasing trend to being constrained on both export to South Australia and import to

Victoria. Heywood bound mainly in the direction of export to South Australia.

VictoriaSouth Australia(Murraylink)

Slightly decreasing trend to being constrained on export to South Australia. Murraylink boundmainly in the direction of export to South Australia.

TasmaniaVictoria(Basslink)

Slightly decreasing trend to being constrained on export to Victoria and slightly increasing trend tobeing constrained on import to Tasmania. Basslink bound relatively more frequently in thedirection of import to Tasmania.

4.2 Voltage excursions

Key results from the examination of voltage fluctuations are as follows:

The regions with the most over-voltage events were New South Wales, Victoria, and Tasmania. There is an

increasing trend to overvoltage violations in New South Wales32.

The region with the most under-voltage events was Victoria. There is an increasing trend to under-voltage

violations in Victoria33

.

South Australia and Queensland have experienced relatively few voltage excursions over the last two years.

For more information about these voltage excursions trends see the PSA appendix.

32 This is due to the overvoltage issues at Beaconsfield West. See Table 3-7 for details.33 The under-voltage conditions were observed during planned outages in the vicinity of Heywood.


30/44


4-2 Review of trends AEMO 2012

4.3 Frequency excursions

A measure of the power systems ability to adequately respond to frequency deviations is the time it takes for

frequency to return to the normal operating band. This capability assessment analyses instances where recoveryhas taken longer than five minutes in the mainland regions and ten minutes in Tasmania, which results in a breach

of the frequency operation standard.34

The frequency excursion events can be classified into six types of events as per the frequency operating

standards.35

These include generation events, load events, network events, multiple contingency events,

separation events, and normal events. Figure 4-1 and Figure 4-2 show event compliance with frequency operating

standards over the past 24 months in the mainland regions and Tasmania, respectively, demonstrating no

significant trend.

The number of events that did not meet the frequency operating standards includes the following:

Where recovery took longer than five minutes in the mainland regions and ten minutes in Tasmania.

Where the frequency was outside the containment frequency band.

Figure 4-1 Frequency excursions in the mainland regions by event type

34 AEMC. Availablehttp://www.aemc.gov.au/Panels-and-Committees/Reliability-Panel/Guidelines-and-standards.html. Viewed 26 July 2012.35 See note 29.

0

2

4

6

8

10

12

Number

ofevents

Year

Generation event - Met frequency operating standards Generati on event - Di d not m eet frequency operating standards

Load event - Met frequency operating standards Load event - Did not meet frequency operating standards

Network event - Met f requency operating standards Network event - D id not meet frequency operating standards

Multiple Contingency event -Met frequency operating standards Multiple Contingency event -Did not meet frequency operating standards

Sepera ti on event - Me t f requency ope rati ng standards Separati on even t - Di d not mee t f requency ope ra ti ng standards

Norm al event - Met f requency operating standards Norm al event - Did not m eet frequency operating standards
http://www.aemc.gov.au/Panels-and-Committees/Reliability-Panel/Guidelines-and-standards.htmlhttp://www.aemc.gov.au/Panels-and-Committees/Reliability-Panel/Guidelines-and-standards.htmlhttp://www.aemc.gov.au/Panels-and-Committees/Reliability-Panel/Guidelines-and-standards.html


31/44

AEMO 2012 Review of trends 4-3

Figure 4-2 Frequency excursions in Tasmania by event type

0

50

100

150

200

250

300

Numberofevents

Year

Generati on even t - Met frequency ope ra ti ng standards Genera tion event - D id no t mee t f requency ope rati ng standards

Load event - Met frequency operating standards Load event - Did not m eet frequency operating standards

Network event - M et frequency operating standards Network event - D id not meet f requency operating standards

Multiple Contingency event -Met frequency operating standards Multiple Contingency event -Did not meet frequency operating standards

Se pe ra ti on e ve nt -M et fre qu en cy o pe ra ti ng stan da rd s Sep arati on e ven t -D id no t m ee t f re qu ency o pe ra ti ng stan da rd s

Norm al event -Met frequency operating standards Norm al event - Did not meet frequency operating standards


32/44


4-4 Review of trends AEMO 2012



33/44

AEMO 2012 Inputs and assumptions 5-1

CHAPTER 5 - INPUTS AND ASSUMPTIONS

5.1 Maximum demand projectionsThe PSA assessments maximum demand projections are consistent with the medium scenario maximum demand

projections developed for the 2012 NEFR.

Table 5-1 lists the 10% and 50% POE maximum demand projections for each region.

Table 5-1 Regional maximum demand projections (MW)

Region

10% POE 50% POE

Summer

201213

Winter

2013

Summer

201314

Winter

2014

Summer

201213

Winter

2013

Summer

201314

Winter

2014

Queensland 9,299 8,880 9,558 9,200 9,007 8,510 9,262 8,818

New South Wales 14,065 14,032 14,289 14,115 13,399 13,511 13,609 13,581

Victoria 10,624 8,849 10,877 8,972 9,690 8,576 9,921 8,707

South Australia 3,271 2,596 3,332 2,627 2,990 2,487 3,045 2,516

Tasmania 1,412 1,813 1,420 1,851 1,371 1,763 1,381 1,799

Low demand

The PSA assessments low demand estimates are based on low demand periods over the last two years. The

interconnector capability and voltage control studies used low demand figures from 26 December 2011.

Table 5-2 lists the low demand figures for each region.

Table 5-2 Interconnector capability and voltage control study low demand snapshots (MW)

Region Low demand

Queensland 4,021

New South Wales 5,550

Victoria 3,842

South Australia 893

Tasmania 804


34/44


5-2 Inputs and assumptions AEMO 2012

Frequency control study demand

The frequency control study used selected historical demand snapshots observed the past 2 years:

The high demand, high export study used high demand cases corresponding to periods of high interconnector

export.

The high demand, high import study used high demand cases corresponding to periods of high interconnector

import.

The low demand, high export study used low demand cases corresponding to periods of high interconnector

export.

The low demand, high import study used low demand cases corresponding to periods of high interconnector

import.

Table 5-3 lists the high and low demand cases.

Table 5-3 Frequency control study demand cases (MW)

RegionHigh demand, high

importHigh demand, high

exportLow demand, high

importLow demand, high

export

Queensland 8,249 7,951 5,322 4,118

Victoria and SouthAustralia

12,950 8,489 6,543 4,692

South Australia 3,385 2,217 1,084 988

Tasmania 1,607 1,616 902 1,009

5.2 Demand-side participation and non-scheduled

generationThe 2012 PSA incorporates analysis involving the expected level of demand-side participation (DSP)

36published in

the 2011 ESOO, and the contribution from non-scheduled generation in each region consistent with the generation

forecasts provided in the 2012 NEFR. Table 5-4 summarises the forecasts of the contribution from DSP and non-

scheduled generation during summer peaks.

Table 5-4 Regional demand-side participation and non-scheduled generation contribution (MW)

RegionDemand-side participation Non-scheduled generation

201213 201314 201213 201314

Queensland 61 63 163 169

New South Wales 98 100 134 137

Victoria 100 100 55 56

South Australia 49 52 42 43

Tasmania 0 0 91 95

36 The DSP values published in the 2012 NEFR were not available when the studies for the 2012 PSA were conducted.


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AEMO 2012 Inputs and assumptions 5-3

5.3 Minimum reserve levels

The Reliability Panel has determined that no more than 0.002% of demand in any region should be interrupted due

to a lack of available supply. AEMO translates this requirement into an MRL for each region, which is used in

operational forecasts. Table 5-5 lists the MRLs, last updated by AEMO in mid-2011.

Table 5-5 Minimum reserve levels (MW)

Queensland New South Wales Victoria and South Australiaa

Tasmania

201213 and201314

913 -1,564

VIC Reserve >= 205.00

5.88 * VIC Reserve + SA Reserve >= 1,237.88

1.33 * VIC Reserve + SA Reserve >= 228.00

0.43 * VIC Reserve + SA Reserve >= -40.53

0.23 * VIC Reserve + SA Reserve >= -147.55

SA Reserve >= -368.00

144

a. The MRLs for Victoria and South Australia are shared, dynamic MRLs. For more information see the AEMO website (availablehttp://www.aemo.com.au/electricityops/mrl.html.Viewed 24 July 2012).

5.4 Wind generation

The 2012 PSA considers scenarios involving high and low wind generation cases, based on current installed wind

generation capacity as well as committed wind generation projects scheduled forcommissioning within the PSAs

outlook period. Outputs were estimated by assuming all wind farms operating at full capacity for the high wind

generation case37

, and at zero output for the low wind generation case.

All the advanced proposals have estimated commissioning dates prior to the end of June 2014.

All the publicly announced proposals have estimated commissioning dates prior to the end of June 2015.

The wind farm contribution factors assumed for the reserve capacity studies are published in the 2011 ESOO,

Chapter 8, Table 8.7.38

5.5 Future projects and generation retirement

The 2012 PSA models all committed generation projects listed in the Generation Information Page that are due to

be commissioned during the PSAs outlook period (to the period ending 30 June 2014). Generation retirements

considered by the Expected scenario are also consistent with the Generation Information Page.

In the Sensitivity scenario, the withdrawal of 1,000 MW of older generation is assumed to occur on 1 July 2012, in

addition to any generation retirements identified by the Generation Information Page.

All committed transmission projects listed in the 2011 NTNDP, updated in May 2012, and due for completion before30 June 2014, have also been modelled.

37 High wind generation in South Australia is constrained by the requirement for a minimum number of synchronous units with power system

stabilizers in service in South Australia as per limit advice received from ElectraNet at the time the s tudies were conducted (which has since been

updated). High wind generation for a Tasmanian separation event may be constrained by the minimum fault level requirement in Tasmania to

avoid inverter commutation instability.38 AEMO. Available http://www.aemo.com.au/en/Electricity/Planning/~/media/Files/Other/planning/0410-0079%20pdf.ashx. Viewed 24 July 2012.
http://www.aemo.com.au/electricityops/mrl.htmlhttp://www.aemo.com.au/electricityops/mrl.html


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5-4 Inputs and assumptions AEMO 2012



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AEMO 2012 Important notice D1

IMPORTANT NOTICE

AEMO publishes this document to provide technical and market data and information regarding the supply anddemand balance in the National Electricity Market (NEM) for the next two years. In preparing this document, AEMO

has used information available as at 3 July 2012, unless otherwise specified. Some information available after 3

July 2012 might have been included in this publication where practical.

AEMO has made every effort to ensure the quality of the information in this publication but cannot guarantee that

information, forecasts and assumptions are accurate, complete or appropriate for your circumstances. This

publication does not include all of the information that an investor, participant or potential participant in the NEM

might require, and does not amount to a recommendation of any investment.

Anyone proposing to use the information in this publication (including information and reports from third parties)

should independently verify and check its accuracy, completeness and suitability for purpose, and obtain

independent and specific advice from appropriate experts.

Accordingly, to the maximum extent permitted by law, neither AEMO nor any of AEMOs advisers, consultants orother contributors to this publication (or their respective associated companies, businesses, partners, directors,

officers or employees):

a) makes any representation or warranty, express or implied, as to the currency, accuracy, or completeness of

the information in this publication; or

b) has any liability (whether by reason of negligence or otherwise) for any statements, opinions, information or

matter contained in or derived from, or for any omission from, this publication, or in respect of a persons use

of the information in this publication.

Copyright Notice

2012 Australian Energy Market Operator Limited. The material in this publication may be used in accordancewith the copyright permissions on AEMOs website.
http://www.aemo.com.au/en/About-AEMO/Copyright-Permissionshttp://www.aemo.com.au/en/About-AEMO/Copyright-Permissions


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D2 Important notice AEMO 2012



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AEMO 2012 List of NTNDP zones M1

LIST OF NTNDP ZONES

Abbreviation Zone

NQ North Queensland

CQ Central Queensland

SEQ South-East Queensland

SWQ South-West Queensland

NNS Northern New South Wales

NCEN Central New South Wales

SWNSW South-West New South Wales

CAN Canberra

NVIC Northern Victoria

LV Latrobe Valley

MEL Melbourne

CVIC Country Victoria

TAS Tasmania


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M2 List of NTNDP zones AEMO 2012



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AEMO 2012 List of measures and abbreviations M3

LIST OF MEASURES AND ABBREVIATIONS

Units of measure

Abbreviation Unit of Measure

CO2-e carbon dioxide equivalent

GWh Gigawatt hours

KT Kilotonnes

MW Megawatts

MWh Megawatt hours

TWh Terawatt hours

t CO2-e/MWh Tonnes of CO2-e per megawatt hour

Abbreviations

Abbreviation Expanded Name

AEMC Australian Energy Market Commission

AEMO Australian Energy Market Operator

CCGT Combined-cycle gas turbine

CFC Contracts for Closure

DSP Demand-side participation

EAAP Energy Adequacy Assessment Projection

ESOO Electricity Statement of Opportunities

GPG Gas powered generation

MD Maximum demand

MRL Minimum Reserve Level

MT PASA Medium-term Projected Assessment of System Adequacy

NEM National Electricity Market

NER National Electricity Rules

NTNDP National Transmission Network Development Plan

OCGT Open-cycle gas turbine

PASA Projected Assessment of System Adequacy

POE Probability of exceedence

PSA Power System Adequacy Two Year Outlook

RERT Reliability and Emergency Reserve Trader


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M4 List of measures and abbreviations AEMO 2012

Abbreviation Expanded Name

USE Unserved energy


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AEMO 2012 Glossary G1

GLOSSARY

Term Definition

Demand-side participation (DSP)The situation where customers vary their electricity consumption in

response to a change in market conditions, such as the spot price.

Electricity Statement of

Opportunities (ESOO)

Document published by AEMO each year that provides supply and

demand balance forecasts for each region for a 10-year outlook period.

Before 2012, the ESOO included annual energy and maximum demand

projections that are now published in the National Electricity Forecasting

Report (NEFR).

Energy Adequacy Assessment

Projection (EAAP)

A tool used by AEMO to perform a quarterly assessment of energy

limitation impacts in the NEM due to factors such as drought and fuel

shortages.

Energy limitedA generating unit that cannot operate at full capacity over the long term

due to fuel or other energy source limitations.

Frequency control ancillary services

(FCAS)

This refers to the ability to automatically control generation or load in

response to deviations in power system frequency. AEMO ensures there

is sufficient FCAS enabled at all times to maintain power system

frequency within the Reliability Panels frequency operating standards.

Frequency operating standards

System standards determined by the Reliability Panel and published by

the Australian Energy Market Commission (AEMC), which specify the

frequency levels for power system operation.

Maximum demand

The highest amount of electrical power delivered, or forecast to be

delivered, over a defined period (day, week, month, season, or year)

either at a connection point, or simultaneously at a defined set of

connection points.

Medium-Term Projected

Assessment of System Adequacy

(MT PASA)

A tool used by AEMO to perform a weekly assessment of the reserve

capacity outlook for the next two years.

Minimum reserve level (MRL)

The reserve margin required in a region to meet the Reliability Standard

as calculated using 10% probability of exceedence (POE) scheduled

maximum demand conditions.

National Electricity Forecasting

Report (NEFR)

Document published by AEMO each year that provides annual energy

and maximum demand projections for each region for a 10-year outlook

period.


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Term Definition

Network control ancillary service

A service identified in clause 3.11.4(a) (of the National Electricity Rules)

which provides AEMO with a capability to control the real or reactive

power flow into or out of a transmission network in order to: Maintain the transmission network within its current, voltage or stability

limits following a credible contingency event, or Enhance the value of spot market trading in conjunction with the

central dispatch process.

Probability of exceedence (POE)

Statistical likelihood that an estimate may be met or exceeded, and used

to express long-term demand projections where a number of factors

influence the actual outcome.

For example, a 10% POE maximum demand projection is expected to be

met or exceeded, on average, 1 year in 10.

Reactive Power Ancillary Services

(RPAS)

RPAS

Power System Adequacy 2012

Documents

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