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 plant allowed 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 357MW Imminent 143MW Proposed 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 ,000 1,500 2,000 2,500 3,000 3, s1930s1940s1950s1960s1970s1980s1990ssince 2000 length of transmission lines built (km) 0 5,000 10,000 15,000 20,000 25,000 30,000 35,000 40,000 45,000 50,000 length builtGenerated electricity generation (GWh) mid-decade

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.

Constrained wind generation

As variable as ever

Low output in first half of 2008 Hydro Inflows 38% 0f average

Correlation of wind generation Correlation over 3 years, r 2 =0.68

Correlation of wind generation Correlation over 12 months, r 2 =0.17

Wind Generation Investigation Project (WGIP) Four phases Wind Generation Development Scenarios Implications Possible 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 MW10000 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 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.