SOME NSW SYSTEM PLANNING ISSUES

Dr Col ParkerManager/System Planning & Analysis

David Hill’s Contributions from a NSW planning perspective

• Dynamics of voltage collapse• Modelling of loads and load dynamics • Direct methods of transient stability• Stability - theory• Excitation system control• Power system analysis • Contributions via:

– Papers– Discussion– Joint R&D work with TransGrid– Research leader to later generations

Contents

• Background - NSW system• 500 kV system developments• Damping issues• Wind generation• Load dynamics• Transient stability capability• Diverse sources of generation

Background- NSW main system

NSW is part of the interconnected eastern Australian electricity system

4800 km AC mainland system

HVDC cable To Tasmania

HVDC link NSW - Qld

HVDC link Vic - SA

0

2000

4000

6000

8000

10000

12000

14000

16000

Qld NSW Vic SA Tas

Forecast power demands (MW) summer 2009/10

NSW main systemLismore

Armidale

Tamworth

Muswellbrook

Liddell/BayswaterWellington

Mt Piper/W’Wang

Newcastle

Eraring/Vales/Munmorah

Sydney

WollongongMarulan

Bannaby

Yass

Wagga

JinderaT3

T1/T2

Murray

Canberra

Kangaroo Valley

Tuggerah

CoffsHarbour

Load 15,000 MWCoal fired generation 11,900 MWGas turbines 1,800 MWSnowy import 3200 MWImport from Qld 1250 MW

500, 330, 220, 132 kVTransmission (12500 km)

Major power station centresLismore

Armidale

Tamworth

Muswellbrook

Liddell/BayswaterWellington

Mt Piper/W’Wang

Newcastle

Eraring/Vales/Munmorah

Sydney

WollongongMarulan

Bannaby

Yass

Wagga

JinderaT3

T1/T2

Murray

Canberra

Kangaroo Valley

Tuggerah

CoffsHarbour

GTs

Coal

Snowyhydro

Mt Piper Power Station (2 x 700 MW units)

Tallawarra GT station (422 MW co-generation)

Interconnection capability(MW)

Lismore

Armidale

Tamworth

Muswellbrook

Liddell/BayswaterWellington

Mt Piper/W’Wang

Newcastle

Eraring/Vales/Munmorah

Sydney

WollongongMarulan

Bannaby

Yass

Wagga

JinderaT3

T1/T2

Murray

Canberra

Kangaroo Valley

Tuggerah

CoffsHarbour

Up to 400

To 1250

10001900Transfer limitations:•Line ratings•Voltage control•Response to large disturbances•Damping of small oscillations

500 kV Developments

Present Core System

Muswellbrook

Liddell /BayswaterWellington

Mt Piper / Wallerawang

Sydney

Wollongong

Kangaroo ValleyYass

Canberra

Murray

Lower Tumut

Newcastle

Eraring / Vales Pt/ Munmorah

Tuggerah

Marulan

Upper Tumut

To Northern NSW and QLD

To Victoria

Muswellbrook

LiddellWellington

Mt Piper / Wallerawang

Sydney

Wollongong

Kangaroo ValleyYass

Canberra

Murray

Lower Tumut

Newcastle

Eraring / Vales Pt/ Munmorah

Tuggerah

330 kV Switchyard / Substation

330 kV Line

500 kV Line Operating at 330 kV

Legend

Marulan

Upper Tumut

To Northern NSW and QLD

To Victoria

Bannaby

Bayswater

Western 500 kV Upgrade

(Complete early2010)

Lismore

Armidale

Tamworth

Muswellbrook

Liddell/BayswaterWellington

Mt Piper/W’Wang

Newcastle

Eraring/Vales/Munmorah

Sydney

WollongongMarulanYass

Wagga

JinderaT3

T1/T2

Murray

Canberra

Kangaroo valley

Tuggerah

CoffsHarbour

10,000 MW75% of NSW Demand1/3rd of NEM demand

Power from Queensland

Power from Victoria and Snowy

Power from NSW Generators

0.50.60.70.80.9

11.1

0 20 40 60 80 100

Seconds

Volts

pu

132 kV

330 kV

Line trip

Sydney voltage levels

Voltage control

Emerging Issues

• Part of the need for system reinforcement is to provide adequate voltage control

• Voltage stability determined by the dynamic response of the load to disturbances

• Potential to co-ordinate control of generators, SVCs and capacitor bank switching

• New SVCs – how much reactive support needs to be dynamic and how much can be static

LiddellWellington

Mt Piper / Wallerawang

Sydney

WollongongYass

Canberra

Murray

Lower Tumut

Newcastle

Eraring/ Vales Pt / Munmorah

Marulan

Upper Tumut

To Northern NSW and QLD

To Victoria

Bannaby

Bayswater

Bannaby –Sydney 500 kV

QLD

NSW

VICSA Dederang

System Oscillatory Damping

First Synchronisation of Queensland System 1/12/2000

QNI

140

150

160

170

180

190

0 20 40 60 80 100 120 140 160

Seconds

MW

Measured power flow on one Dederang - South Morang 330kV circuit in Victoria at the time of the first synchronisation of Queensland to the rest of the eastern Australian system.

Measured power flow on one Dederang - South Morang 330kV circuit in Victoria at the time of the first synchronisation of Queensland to the rest of the eastern Australian system.

First synchronisation on QNI

CentralQueensland

SouthernQueensland

LatrobeValley

Port Augusta

Adelaide Metro

Snowy Hydro

Hunter ValleyCentral CoastCentral West

Brisbane

Sydney

Melbourne

Adelaide

275kV

330kV

500kV

275kVCanberra

Springs and masses analogy

500/330 kV

Damping - Progress• Interconnector testing has been undertaken over last 8 years to

understand the damping issues and to measure the damping• Steady-state stability modelling indicates that the damping should

be better than as measured.• Generator Power System Stabilisers have been tuned• Power Oscillation Dampers fitted to SVCs near QNI• QUT and Don Geddey’s work on deriving damping information from

continuous voltage-angle measurements from GPS-synchronised on-line recorders at:– South Pine in Qld, – Sydney West in NSW, – Rowville in Victoria; and – Para in South Australia

• On-line measurement is based on the QUT/Geddey (TransGrid) algorithm

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 50

1

2

3

4

5

6

7

8

9

10

11Magnitude spectra of (S−B) dΘ/dt signals during 28−29/5/02

Frequency (rad/s)

Mag

nitu

de o

f FT

10:00 − 14:00 28/518:00 − 22:00 28/502:00 − 06:00 29/5

SYDNEY - BRISBANE

Sample magnitude spectra of Sydney – Brisbane voltage-angle differences

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 50

1

2

3

4

5

6

7Magnitude spectra of (M−A) dΘ/dt signals during 28−29/5/02

Frequency (rad/s)

Mag

nitu

de o

f FT

10:00 − 14:00 28/518:00 − 22:00 28/502:00 − 06:00 29/5

Sample magnitude spectra of Melbourne - Adelaide voltage-angle differences

Melbourne –Adelaide

Victorian generators

Queensland generators

NSWgenerators

SA generators

3.5 rad/sec mode eigenvectors (speed states)Victorian vs SA generators

Queensland generators

NSWgenerators SA

generators

2.5 rad/sec mode eigenvectors (speed states)NSW vs SA & Qld generators

Queensland generators

Victorian generators

Queensland generators

SA generators

1.8 rad/sec (QNI) mode eigenvectors SA & Victoria vs Qld generators

QNI(1.8 rad/s) mode damping (measured and simulated) 

‐0.9

‐0.85

‐0.8

‐0.75

‐0.7

‐0.65

‐0.6

‐0.55

‐0.5

‐0.45

‐0.4

‐0.35

‐0.3

‐0.25

‐0.2

‐0.15

‐0.1

‐0.05

0

1/03 0:00

1/03 12:00

2/03 0:00

2/03 12:00

3/03 0:00

3/03 12:00

4/03 0:00

4/03 12:00

5/03 0:00

5/03 12:00

6/03 0:00

6/03 12:00

7/03 0:00

7/03 12:00

8/03 0:00

8/03 12:00

9/03 0:00

9/03 12:00

10/03 0:00

10/03 12:00

11/03 0:00

real part (Np/s)

Original Data OSM

No damping

Well damped

Measured

Modelled

Continuing work

• Complete checking of all NEM generator models

• Switching the SVC Power Oscillation Dampers on and off – to measure their impact

• Analysis to estimate the “effectiveness” of the generator Power System Stabilisers and SVC Power Oscillation Dampers

QNI(1.8 rad/s) mode damping(measured and modified simulated) 

‐0.9

‐0.85

‐0.8

‐0.75

‐0.7

‐0.65

‐0.6

‐0.55

‐0.5

‐0.45

‐0.4

‐0.35

‐0.3

‐0.25

‐0.2

‐0.15

‐0.1

‐0.05

0

1/03 0:00

1/03 12:00

2/03 0:00

2/03 12:00

3/03 0:00

3/03 12:00

4/03 0:00

4/03 12:00

5/03 0:00

5/03 12:00

6/03 0:00

6/03 12:00

7/03 0:00

7/03 12:00

8/03 0:00

8/03 12:00

9/03 0:00

9/03 12:00

10/03 0:00

10/03 12:00

11/03 0:00

real part (Np/s)

Modified Paramater: Glad PSS: 0.42; Blackwall POD: 0.38

OSM

Measured

Modelled with modifications

Wind generation –connection and impact

SWQ

FNQ

SEV

CS

SWV

NWV

WIND FARM RESOURCELOCATIONS

FNQ – Far North QueenslandNQ – North QueenslandCQ – Central QueenslandSWQ – South West Queensland

FWN – Far West NSWMRN – Murray NSWSEN – South East NSWWN – West NSWMRN – Marulan NSWHUN – Hunter NSWNEN – New England NSW

NWV – North West VictoriaSWV – South West VictoriaSEV – South East Victoria

CS – Central SouthWCS – West Coast SAEPS – Eyre Peninsula SAYPS – Yorke Peninsula SAMNS – Mid North SAFLS – Fleurieu SA

NWT – North West TASNET – North East TASWCT – West Coast TASST – Southern TAS

WCS

EPSYPS

FLS

MNS

NWT

WCT

NET

ST

FWN

MRN

WEN

HUN

NEN

MRN

SEN

NQ

CQ

NEM wind areas

FWN

MRN

WEN

HUN

NEN

MRN

SEN

NSW wind areas

Lismore

Armidale

Tamworth

Muswellbrook

Liddell/BayswaterWellington

Mt Piper/W’Wang

Newcastle

Eraring/Vales/Munmorah

Sydney

WollongongMarulanYass

Wagga

JinderaT3

T1/T2

Murray

Canberra

Kangaroo valley

Tuggerah

CoffsHarbour

NSW wind Farms – operating – 170 MW

Capital 141 MW

Cullerin Range 30 MW

Lismore

Armidale

Tamworth

Muswellbrook

Liddell/BayswaterWellington

Mt Piper/W’Wang

Newcastle

Eraring/Vales/Munmorah

Sydney

WollongongMarulanYass

Wagga

JinderaT3

T1/T2

Murray

Canberra

Kangaroo valley

Tuggerah

CoffsHarbour

Wind Farms – inquiries to TransGrid(> 4500 MW)

1200 MW

900 MW

1600 MW

>1000 MW

Lismore

Armidale

Tamworth

Muswellbrook

Liddell/BayswaterWellington

Mt Piper/W’Wang

Newcastle

Eraring/Vales/Munmorah

Sydney

WollongongMarulanYass

Wagga

JinderaT3

T1/T2

Murray

Canberra

Kangaroo valley

Tuggerah

CoffsHarbour

Wind generation – import to NSW

Capital 141 MWCullerin Range 30 MW

Import from Victoria and South Australia

TransGrid Wind Farm planning activities• Assessing connection applications • System planning is based on scenario analysis

for the future – this includes wind farm development scenarios across NSW

• Other work on:– Network modelling and wind traces for market

simulations– Developing a wind expansion plan from the market

modelling – Aim in the longer-term to rank sites according to

connection costs, deep network costs and generation revenue

0

10

20

30

40

50

60

70

80

90

100

0 10 20 30 40 50 60 70 80 90 100

% of time

% o

f ins

talle

d ca

paci

tyTypical wind farm generation duration curve

2% of energy output above 75% of capacity

Output at time of NSW peak demand

HV bus LV bus

Wind Farm

Wind Farm performance with system disturbances

Main systemloads

Wind Farm MW output

HV bus fault

LV bus fault

HV bus fault

LV bus fault

Wind Farm voltage

Wind farm trips

Planning issues for wind farm connection

• How much transmission should we build to: – connect wind farms, – transfer power to the load; and – import wind energy to NSW

• Capability of single wind farms to ride through faults

• NSW system-wide impact of high wind penetration (ride through and inertia)

• Statcoms / SVCs – distributed or centralised

Load Dynamics

• Planning studies range from steady-state analysis to dynamic analysis

• Example of supply to a paper mill load in NSW

80 km 10 km 90 km

Rural substation

Paper mill substation

Yass330/132 kV substation

Wagga330/132 kV substation

External parallel 330 kV and 132 kV system

132 kV system

42- j41 39-j3 80 +j25

Paper mill substation

132 kV system

Normal power flows

-30

-25

-20

-15

-10

-5

0

5

10

15

0.78 0.8 0.82 0.84 0.86 0.88 0.9 0.92 0.94 0.96

Volatge pu

Mva

r gen

erat

ion

Outage of a 132 kV line – Steady-state QE relationship

After tap changers operate

Before tap changers operate

Voltage indices 1 and 3

0

0.2

0.4

0.6

0.8

1

1.2

0 20 40 60 80 100 120 140 160 180 200

Time (cycles)

Volta

ge (p

u)

Line opening without a fault

Rural substation 132 kV bus

Paper mill 11 kV

0

0.1

0.2

0.3

0.4

0.5

0.6

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0

Time (seconds)

Reac

tive

pow

er (p

er u

nit)

Reactive power demand at the supply point

0

0.2

0.4

0.6

0.8

1

1.2

-10 10 30 50 70 90 110 130 150

Time (cycles)

Vol

tage

(per

uni

t)3-phase fault on a connecting 132 kV line

Rural substation 132 kV bus

Paper mill 11 kV

0

0.2

0.4

0.6

0.8

1

1.2

-10 10 30 50 70 90 110 130 150

Times (cycles)

Vol

tage

(oer

uni

t)3-phase fault – remote 132 kV line

Paper mill 11 kV

Rural substation 132 kV bus

Transient Stability Capability• Transient stability governs power transfer

capability at times:– From NSW to Queensland– Queensland to NSW– NSW to Victoria / SA– Victoria to NSW

• Also necessary to ensure that:– Line protection systems are adequate within NSW to

avoid degradation of inter-state transfer limits; and – Subsystem lines do not trip during system swings.

Analysis

• Detailed generator modelling• Loads represented by composite models including

induction machines• Detailed network model• Numerous critical disturbances with different outcomes• Expected fault clearance times• Applies a time domain simulation of algebraic-differential

equations describing the network and machine dynamics• Modes of instability – system separation along different

network cutsets

Present load model

HV

LV

Impedance

Induction motor

SaturationResistive

load Shunt capacitors

Bus at 1pu voltage

Technical envelope

NSW to Queensland

NSW to Victoria

Victoria to NSW

Queensland to NSW

Stable region

Limit with safety margin

Hunter Valley 330 kV line faultLismore

Armidale

Tamworth

Muswellbrook

Liddell/BayswaterWellington

Mt Piper/W’Wang

Newcastle

Eraring/Vales/Munmorah

Sydney

WollongongMarulan

Bannaby

Yass

Wagga

JinderaT3

T1/T2

Murray

Canberra

Kangaroo Valley

Tuggerah

CoffsHarbour

2-phase line-to-ground fault

780 MW

-80

-60

-40

-20

0

20

40

60

80

0 1 2 3 4 5 6 7 8 9 10

Time (sconds)

Angl

e (d

egre

es)

Bayswater

Generator rotor angles

Tarong (in Qld)

Outcome is dependent on:• Fault clearance times (protection and

circuit breaker)• Generator inertia (including embedded

sources)• Excitation system performance • Load drop compensation setting• Load modelling• Generator models need to match reality

-200

-150

-100

-50

0

50

100

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0

Time (seconds)

Ang

le (d

egre

es)

Delayed fault clearance - unstable outcome

Bayswater

Tarong (in Qld)

0

20

40

60

80

100

120

140

160

180

200

0 1 2 3 4 5 6 7 8 9 10

Time (seconds)

Ang

le d

iffer

ence

(deg

rees

)

Stability outcomes are dependent on system parameters

Nominal trajectory

Uncertainties and sensitivities

Ian Hisken’s work on Trajectory Sensitivity– Identify variations from the nominal trajectory

of the system following a disturbance– Ranking relative influence of parameters (load

and generator)– Setting safety margins

Issues with diverse generation

• Wind farm models developed by proponents (translated to models to match TransGrid software)

• Reactive supply (wind farms vs coal-fired stations)• Wind farm ability to ride-through line faults• Wind displacing coal – inertia impacts on transient stability• High penetration implies variable flows – what voltage control is

required?• Interconnection capability and variable flows from the south of NSW• Future load modelling with embedded generation• Transmission investment – how much and when?• Line ratings – correlation with wind output• Opportunities to maximise capability by co-ordinating controls• Technical envelope:

– Extra variables– Renewables and controls must be modelled (or can simplified

equivalent models be used?)

The light on the hill• Full understanding of load parameters

for– transient stability, voltage control, steady-

state stability• Co-ordinated control of diverse sources

– maximising power transfer capability• Direct methods of transient stability –

ability to directly define the technical envelope

• Damping – modelled outcome to match measured