Wind Generation in New Zealand

Kieran Devine, Doug Goodwin

System Operations

Transpower New Zealand Limited

Overview

• New Zealand and the Power System

• New Zealand’s Energy Strategy

• The Electricity Market

• Wind Generation in New Zealand

• Wind Integration Investigations

New Zealand’s Place in the World

No opportunity for interconnection

Have to meet all our own electricity needs

New Zealand power system• Two AC island power systems

connected by an HVDC link

• Peak/Minimum demand– North Island 4500/1680 MW (37%)

– South Island 2250/1300 MW (58%)

• Installed capacity (generation)– North Island 5300 MW

– South Island 3400 MW

• Total Energy, 42,000 GWhr

NZ Energy Strategy (2008)

• Generation will be 90% renewable by 2025

• Currently 65% renewable: 54% hydro, 8% geothermal, 3% wind

• Wind is expected to be the main contributor to achieving the 90% target

• No new baseload thermal (coal or gas) generating plantallowed for 10 years

• Emissions trading regime has been introduced

New Zealand Electricity Market

• Security constrained economic dispatch– Gross pool, energy market, no capacity payments– Compulsory market, but no compulsion to offer– Locational nodal prices, no price caps– Energy and reserves co-optimised– No rights to transmission capacity

Te Apiti (91 MW)Tararua (161 MW)Te Rere Hau (48 MW)

White Hill (57 MW)West Wind (143 MW)from 2009

Wind resource

Existing 357MWImminent 143MWProposed 2014MW

Hawkes Bay Wind Farm (225 MW)Titiokura (48 MW)Te Waka (102 MW)

Mill Creek (71 MW)

Mount Cass (69 MW)

Project Hayes (630 MW)Kaiwera Downs (240 MW)Mahinerangi (200 MW)

Motorimu (110 MW)

Waverley (135 MW)

Te Uku (84 MW)Taharoa (100 MW)

Transmission and Demand

0

500

1,000

1,500

2,000

2,500

3,000

3,500

1920s 1930s 1940s 1950s 1960s 1970s 1980s 1990s since2000

leng

th o

f tr

ansm

issi

on li

nes

built

(km

)

0

5,000

10,000

15,000

20,000

25,000

30,000

35,000

40,000

45,000

50,000

length built Generated

elec

tric

ity g

ener

atio

n (G

Wh)

mid

-dec

ade

Wind in the Market

• Electricity market and ancillary service market rules are based around

non-intermittent generation• Wind Offers into the market for next day• Currently there is no national wind forecast• Persistence Offer within 2 hour gate closure:

– Offer for next 5 minutes is current output• Wind is occasionally constrained off for

system security reasons.

Te Apiti Constraint - 4 August 2007

-400

-300

-200

-100

0

100

200

20:24:00 21:36:00 22:48:00 00:00:00

Time

Ou

tpu

t o

r tr

ansf

er (

MW

)

Te Apiti HVDC Te Apiti potential

Constrained wind generation

Total NZ Wind Generation (MW)

0

50

100

150

200

250

300

19-Jul-2007 00:00 21-Jul-2007 00:00 23-Jul-2007 00:00 25-Jul-2007 00:00 27-Jul-2007 00:00 29-Jul-2007 00:00 31-Jul-2007 00:00

Date

Ou

tpu

t (M

W)

As variable as ever

Daily NZ wind generation production

0

1000

2000

3000

4000

5000

6000

7000

1/07/2007 31/07/2007 30/08/2007 29/09/2007 29/10/2007 28/11/2007 28/12/2007 27/01/2008 26/02/2008 27/03/2008 26/04/2008 26/05/2008 25/06/2008

Day

Pro

du

cti

on

(M

Wh

)

MWh 30 per. Mov. Avg. (MWh)

Low output in first half of 2008

Hydro Inflows 38% 0f average

28 December 2007

0

10

20

30

40

50

60

70

80

90

100

00:00:00 04:48:00 09:36:00 14:24:00 19:12:00 00:00:00

Time

Ou

tpu

t (M

W)

Te Apiti Tararua III

`

Correlation of wind generation

Correlation over 3 years,

r2=0.68

31 January 2008

0

50

100

150

200

250

00:00:00 06:00:00 12:00:00 18:00:00 00:00:00

Time

Win

d g

en

era

tio

n o

utp

ut

(MW

)

Manawatu wind generation White Hill

`

Correlation of wind generation

Correlation over 12 months, r2=0.17

Wind Generation Investigation Project (WGIP)

• Four phases

Wind Generation

Development Scenarios

ImplicationsPossible Options

Preferred options

What may happen with wind generation development in NZ

What will the effects be?

What can we do?

What are the preferred options

WGIP Recommendations

• Wind generation capability:– Review ancillary services cost allocations– Review ride through capability requirements– Need for tested wind farm models

• Pre-dispatch processes– Incorporation of wind generation forecasts– Ability to meet large sudden unpredicted changes

• Continue to monitor, currently only 3 years data

Amount of wind generation

1000 MW100 MW 10000 MW

Effect

Noticeable

Critical

Lack of frequency support:- Increased reserves costs

Lack of voltage support:- Increased costs- More transmission reactive devices

Variability:- Increased frequency regulation costs

Unpredictability:- Market outcomes- Security

Conclusions (Part 1)

• Most of the potential issues are moderate in impact or will occur 5-10+ years in the future

• No immediate need to limit the connection of wind generation

• No defined technical upper limit to wind generation

• The lack of operational experience and the initial geographic concentration of wind generation in NZ places limitations on the analysis carried out

Conclusions (Part 2)

• Main issues for immediate further attention arise from effect of variability on pre-dispatch processes

• Technical capability of wind generation much improved over last few years

• Some areas for standards and code changes:– Ride through capability– Effect of variability and capability on ancillary services

requirements

• Other issues are less urgent and may be dealt with by normal regulator processes used to develop codes.