Principles and Issues Relating to the Interconnection of Wind Power Power System Conference, Clemson, South Carolina, March 8-11, 2005 Zhenyu Fan & Johan Enslin KEMA T&D CONSULTING 3801 Lake Boone Trail, Suit 200 Raleigh, NC 27607
Overview: • Study Background • Key Issues • Objectives & Scope • Case Studies • Summary
Wind Power is growing! • Germany: 12,001 MW • Spain: 4830 MW • US: 4275 MW • Denmark: 2880 MW • India: 1702 MW Source: AWEA’s Global Market Report
Region Peak Load MW Installed WindMW Penetration Denmark 5,000 3,100 62% Germany 77,000 14,600 19% Spain 36,000 6,200 17 % The Netherlands 14,000 1,000 7% Continental USA 808,000 6,740 0.8% Texas 63,000 1,288 2% New Mexico 1,500 265 17% Table 1: Example of wind systems and installed penetration levels
Wind Power Interconnection Studies • Interconnection procedures are not uniform • In general, interconnection procedures require: • to apply for a queue position; • system feasibility, system impact, and facilities studies; • interconnection and construction agreements; • construction of interconnection facilities, and network upgrades if required. • FERC governs the generation interconnection process
Interconnected Issues: • Power Flow • Short Circuit • Transient Stability • Electromagnetic Transient
Interconnected Issues (Cont.): • Protection • Power Leveling and Energy Balancing • Power Quality
Network Interface Options • A – Direct link, no compensation • B – SVC, reactive power, voltage • C – STATCOM, added power quality • D – STATCOM with battery, added power balance, trading, UPS, • Black-start, etc.
Case Studies: • California ISO System • Dutch Project
California ISO System: • CA Wind Resources • Areas designated "Good" are roughly equivalent to an estimated mean annual power at 10 meter height of 200 Watts/square meter to 300 W/m2 and "Excellent" to above 300 W/M2. • In the year 2000, wind energy in California produced 3,604 million kilowatt-hours of electricity, about 1.27 percent of the state's total electricity. That's more than enough to light a city the size of San Francisco.
California ISO System: • CA Electricity Market • The CA ISO 2004 Summer peak load is 44,422 MW with a minimum projected planning reserve of 16.4% and a corresponding operating reserve of 2,750 MW. Approximately 32,700 MW are thermal units, 2,600 MW are wind with the remaining 18,700 MW consisting of a mix of hydro, pumped storage and solar. • The 2004 base scenario forecast wind capacity for California during summer peaks is only 235 MW (9.0% of the installed wind capacity).
Wind Power Operating Reserve and Regulation Impact • Load forecasting error affects operating reserves while short-term fluctuations in load affect regulation • Forecasting errors should be considered in combination • Geographical dispersion of wind resources tend to reduce the amount of incremental load following requirements
Wind Power Impact on Reliability and System Operation • Hydro-power resources can be used for power balancing wind power plants, • Thermal units on the system would still be used for operating reserves. • System reliability and load following capability will not be affected significantly by the addition of a significant amount of wind generation.
Wind Power Impact on Generation • The decision to build a wind plant depends on many factors. • Capacity factor of CA ISO is 9% on an annual basis, new wind project are likely to have capacity factors in the 35-40% range. • The addition of large amounts of wind generation to a system would have some economic and physical impact on merchant plants in the medium to long run.
Netherlands Project Major Dutch HV Network Upgrades for interconnection of a 6,000 MW offshore wind park in the North Sea
Offshore Wind Energy In Netherlands • 12% of energy within EU should be provided by renewables by the year 2010, with a possible installed wind capacity of at least 40 GW • 6000 MW by 2020 wind power studies • An energy storage system integrated with high power electronics can mitigate interconnection problems
Storage Options for 6 GW Wind Farm VSC Interface • Based on Flow-battery technology • 6,000 M€, 30 years NPV, 1x1 km size • Not feasible by factor 10 as a single solution
Energy Storage • A 2500 MW battery plant will be required • Total capacity is 62 GWh • Based on the difference between low and high APX-values, the profits of the reduction of the number of start/stops, and avoiding the investment cost of the stabilization system, and avoiding of the unbalance cost, the project becomes feasible. • In this case, a seven- to eight-year break-even can be achieved,
Summary • Large-scale wind park requires a different integration approach from those used for smaller wind farms. • Mitigation devices are needed for the interconnection issues with distributed power • Key technologies can minimize the impact on the network • Several functions should be integrated into the functionality of the energy storage system