SLIDE 1

ANTICIPATING AND ADDRESSING

SECURITY CHALLENGES IN AN

EVOLVING POWER SYSTEM

10th October 2016

PRESENTED BY JENNY RIESZ

SLIDE 2

AGENDA

1. Future Power System Security Program

2. Identifying future challenges

3. High priority challenges:

• Frequency control

• Management of extreme power system conditions

• System strength

• Information, models and tools

For each challenge:

• Non-technical introduction

• AEMO’s work program

SLIDE 3

FUTURE POWER SYSTEM SECURITY

• The power system is changing

Conventional generation

Wind & PV

- Variable availability

- Non-Synchronous

Centralised Distributed resources

• What challenges will we encounter?

• How do we maintain power system security?

SLIDE 4

FUTURE POWER SYSTEM SECURITY

(FPSS) PROGRAM

Short-termTo be transparent in how

AEMO intends to meet its

obligations

Long-termTo identify, rank and promote

resolution of long-term

technical challenges

Adapt AEMO’s functions and processes to deliver ongoing

power system security and reliability

SLIDE 5

TIMELINE

2017 →Dec 2016May 2016Dec 2015

Identify challengesAnalysis to define operational bounds

and risks

Identify technical solutions

Develop solution

frameworks

Analysis of other

technical challenges

Where are we at now?

• Identified challenges

• Quantitative analysis underway

• Analysing technical solutions

• Commencing work on implementation frameworks

SLIDE 6

IDENTIFYING CHALLENGES

• Power Systems Issues Technology Advisory Group (PSI-TAG)

o Stakeholder consultation group

o Formed a comprehensive list of challenges

o Prioritised the challenges requiring immediate focus

SLIDE 7

HIGH PRIORITY CHALLENGES

Frequency control

Management of extreme power system

conditions

Visibility of the power system

(information, data and models)

System strength

SLIDE 8

FREQUENCY CONTROL

SLIDE 9

WHAT IS FREQUENCY CONTROL?

LOAD GENERATION

50.0

ImbalanceFrequency changes

Contingency FCAS

• Corrects the generation / load imbalance following major contingency events

Regulation FCAS

• Continually corrects the generation / load imbalance in response to minor deviations

Maintain balance with FCAS:

Frequency Control Ancillary Services

SLIDE 10

FREQUENCY CONTROL ANCILLARY

SERVICES

• Will there be sufficient FCAS in future?

Increased variability in supply and demand may

lead to increasing need for FCAS services

Only conventional units registered to provide FCAS

(retirements anticipated)

Reducing

supply

Increasing

need

SLIDE 11

INERTIA

DEMAND GENERATION

50.0

INERTIA acts

as a “brake”

High inertia → frequency changes slowly

Synchronous generators contribute inertia

(coal, gas, hydro)

NO inertia from non-

synchronous generators

(wind, PV)

As wind & PV displace synchronous

generators, inertia reduces, and the

frequency changes more quickly

SLIDE 12

RATE OF CHANGE OF FREQUENCY

• Following a contingency event (unexpected loss of generation)

o Imbalance causes system frequency to fall

• If “Rate of change of Frequency” (RoCoF) is too high:

o Could result in cascading trip of load or generation

o Emergency control schemes may not prevent system collapse

Contingency event

RoCoF

SLIDE 13

CHALLENGES IDENTIFIED

Challenges: Work Program:

Projecting FCAS Supply-Demand Balance

Review of FCAS Specifications

International Review of Frequency Control Adaptation

Advising on RoCoF System Limits

RoCoF Withstand Capabilities of South Australian Generators

Fast Frequency Response Specification

Insufficient FCAS

High RoCoF

SLIDE 14

MANAGEMENT OF EXTREME POWER

SYSTEM CONDITIONS

SLIDE 15

TWO TYPES OF CONTINGENCY EVENTS

Credible

• Reasonably possible

• Eg: loss of a single transmission line or generating unit

• AEMO must manage proactively

Non-credible

• Less likely

• Eg: loss of multiple transmission lines or generating units

• AEMO has limited powers to manage proactively

UFLS:(Under Frequency Load Shedding)

- “Emergency” mechanism

- Trip load at 49Hz to prevent

complete system collapse

SLIDE 16

CHALLENGES IDENTIFIED

Challenges: Work Program:

UFLS re-design

Exploring OFGS design

Reviewing procedures to operate SA as an island

Rule change proposal

• Broader and more flexible provisions for ‘smarter’ emergency frequency control schemes

• Clarifying obligations, roles and responsibilities

UFLS• May not work properly with high

RoCoF

• May not work properly with DER

OFGS• No emergency scheme for over-

frequency events

Non-credible events• Now more serious consequences,

but AEMO has limited powers to

act pre-emptively

SLIDE 17

SYSTEM STRENGTH

SLIDE 18

SYSTEM STRENGTH

• System strength is a measure of power system stability

• Related to “fault current”

• Synchronous generators contribute fault current (coal, gas, hydro)

• Non-synchronous generators do not (wind, PV)

Wind & PV displace

synchronous generators

Less fault current

System strength reduces

Fault occursSynchronous

generators contribute fault current

Triggers protection systems to detect &

isolate the fault

SLIDE 19

CHALLENGES IDENTIFIED

Challenges: Work Program:

Protection systems• May not work properly in weak

systems

Inverter-connected plant• May not operate as designed in a

weak system

Modelling challenges• Weak systems not always easy to

identify/model

International engagement to identify suitable metrics

Rule change for revision of Generating System Model Guidelines

• Expand the scope of data about plant performance, to improve modelling

Refining power system models

Modelling of the NEM to identify timing and location of challenges

Working with the AEMC on regulatory/frameworks challenges

• Who has responsibility for maintaining system strength?

• What if a retirement causes system strength issues?

Voltages• Greater difficulty maintaining stable

voltages in weak systems

SLIDE 20

INFORMATION, MODELS AND TOOLS

SLIDE 21

INFORMATION, MODELS & TOOLS

Distributed resources displace scheduled

generation

Fewer levers to maintain system

security

Visibility increasingly important

Distributed storage?

Changing customer

behaviour?

Distributed PV?

Electric vehicles?

SLIDE 22

CHALLENGES IDENTIFIED

Challenges: Work Program:

Modelling tools• May not be accurate for the future

power system

Other data gaps• Eg. RoCoF withstand capabilities

Distributed energy

resources• Not visible to AEMO (or

controllable)

• Not well-represented in AEMO’s

models

Assessing requirements for representation of distributed resources in AEMO’s models

Developing tools and capabilities roadmap

Surveying requirements for standing and real-time data

SLIDE 23

SUMMARY

• Future Power System Security (FPSS) Program

• Four work streams:

o Frequency Control

o Managing extreme system events

o System Strength

o Visibility of the power system (information, data and tools)

• We welcome stakeholder engagement