Overview of Major US Wind Integration Studies and Experience

Transcription

1 Overview of Major US Wind Integration Studies and Experience Presented at NCSL Midwest Wind Policy Institute Ann Arbor, MI June 14-15, 2007 J. Charles Smith Executive Director UWIG

2 Outline of Topics Building and Validating Wind Plant Models Recent Studies Dealing With Cost Impacts of Variability and Uncertainty MN NY CA Conceptual EHV Transmission Plan Transmission Recommendations Study Overview -- 2

3 Building and Validating Wind Plant Models Why? Operating characteristics of wind plants are not well known in power system engineering circles Essential for range of electrical-side studies How? Conservative estimates Extrapolations from measurement data + NOAA archive data (wind speed) Meteorological modeling From volumes of historical data and experience (Be Careful!) Better Likely the best for now Have to wait for this Study Overview -- 3

4 Wind Plant Modeling Approach: Re-creating the Weather Use meteorological modeling to simulate weather for historical years e.g. MM5 model used for weather forecasting zoom in for both space and time (e.g. 5 min, 2 mi x 2 mi) Use actual weather to guide simulation, nudge back to reality Save important weather variables at points of interest Wind speed and hub height Temperature Pressure Convert time series of wind speed data to generation using turbine power curves Study Overview -- 4

5 Validation Delta Sector Tower 24 Selected comparisons with measured data Good pattern match at hourly level High correlation between time series Applications to date Xcel/MN Xcel/PSCo NYISO Power (kw) Power (kw) Time Step (1 hr) Delta Sector Tower Time Step (1 hr) Study Overview -- 5

6 Advantages Captures all important aspects of large wind generation scenario for power system studies Common, realistic meteorology for region Effect of geographic separation for points of interest is captured to high degree of accuracy Seasonal and diurnal variability also characterized Historical nature of data simplifies power system analysis Most grid-side quantities for period are known, available from archives (load, line flows, generation, etc.) Any correlations between wind generation and load are embedded in data (if synchronized) Meaningful study scenarios can be readily constructed Downside Computationally intensive Relatively expensive Study Overview -- 6

7 Time Scales of Interest System Load (MW) Time (hour of day) Days Unit Commitment seconds to minutes Regulation tens of minutes to hours Load Following day Scheduling Study Overview -- 7

8 MN 2006 Study Assumptions Meet 15, 20, or 25 percent of MN retail load in 2020 with wind energy Consolidation of 8 MN BAs into 1 MN peak load of 19,000 MW in 2020 In-state capacity of 23,500 MW in 2020 Wind plants distributed in 4 regions of 3 states inside a 450 mi square 5,700 MW wind capacity at 25% energy penetration Transmission interconnection capacity of 6,700 MW as planned, allows for robust market operation Study Overview -- 8

9 Additional Assumptions MISO market currently has 133 GW generation, estimated to be 170 GW by 2020 Minnesota BA assigned responsibility for all reserves and intra-hour resources for balancing Participate in MISO day ahead and hourly markets Day-ahead markets and in-the-day re-dispatch at the hourly level were administered by MISO for the entire footprint. Within the hour balancing assumed done with instate resources Study Overview -- 9

10 Aggregation Reduces Variability Annual histogram of hourly capacity factor for four levels of geographic dispersion. Source: Study Overview MN -- DOC 10

11 Impact on Reserves Reserve Category Base 15% Wind 20% Wind 25% Wind MW % MW % MW % MW % Regulating % % % % Spinning % % % % Non-Spin % % % % Load Following % % % % Operating Reserve Margin % % % % Total Operating Reserves % % % % Estimated Operating Reserve Requirement for MN BAs 2020 Load Source: MN DOC Study Overview -- 11

12 Regulation Requirements Regulation Capacity (% of peak load) Peak Load (MW) Regulation (MW) Approximate regulating requirements for a BA as a function of peak demand. Source: MN DOC Study Overview -- 12

13 Regulating Reserves Balancing Authority Peak Load Regulating Requirement (from chart) Regulating Requirement (% of peak) GRE 3443 MW 56 MW 1.617% MP 2564 MW 48 MW 1.874% NSP MW 104 MW 0.863% OTP 2886 MW 51 MW 1.766% Sum of Regulating Capacity 259 MW Combined MW 137 MW 0.655% Estimated Regulating Requirements for MN BAs Source: MN DOC Study Overview -- 13

14 Impacts Within the Hour QUESTIONS Is control area demand more variable within the hour with wind? What are the consequences? ANSWERS Effect is confined mostly to tail Impact on CPS2 Increase of 1-2 MW/min in loadfollowing capability Study Overview -- 14

15 MN 2006 Study Findings For 3500 to 5700 MW of wind generation delivered to MN load (15 to 25% of retail electric energy sales in 2020): An increase of 12 to 20 MW of regulating capacity No increase in contingency reserves An increase of 5 to 12 MW in five minute variability Incremental operating reserve costs of $0.11 per MWh of wind generation (20% wind case) Variability inside the hour was not a significant cost element in the study No significant congestion issues attributable to wind generation and no periods of negative LMPs under the assumed transmission expansion Study Overview -- 15

16 Integration Cost Unit Commitment Costs $5.00 Integration Cost ($/MWH Wind Energy) $4.00 $3.00 $2.00 $1.00 $ % Wind 20% Wind 25% Wind Penetration Level Unit commitment costs for three penetration levels and pattern years. Cost of incremental operating reserves is embedded. Source: MN DOC Study Overview -- 16

17 MN 2006 Study Summary Electric power system can reliably accommodate addition of wind generation to supply up to 25% of Minnesota retail electric energy sales Total integration operating cost for up to 25% wind energy delivered to Minnesota customers is less than $4.50 per MWh of wind generation Key drivers include: Sufficient transmission Geographically diverse wind scenario Functional consolidation of balancing areas Large MISO energy market; wind forecasts important for market efficiency Since real-time market operates on five-minute increments, further efficiencies could be obtained if out-of-state resources were assumed available to balance within the hour Study Overview -- 17

18 Utility Scale Wind Energy Forecasting Funded in 2005 by Xcel Renewable Development Fund (RDF) Team members: WindLogics EnerNex AREVA Utility Wind Interest Group (UWIG) Goal: Define, design, build and demonstrate a complete wind power forecasting system for use by Xcel system operators. A key objective is to optimize the way that wind forecast information is integrated into the control room environment, and to evaluate the impact of the wind forecast on control room operations. Study Overview -- 18

19 Summary of NYS/GE Operating Cost Impacts Annual Operating Cost Impacts for 2001 Wind and Load Profiles Unit Commitment Total variable cost reduction (includes fuel cost, variable O&M, start-up costs, and emission payments) Total variable cost reduction per MW-hour of wind generation With Day-Ahead Wind Forecasting $ 95M Without Wind Forecasting $ 430M $ 335M $48 / MWh $38 / MWh Wind revenue $ 315M $ 305M Non-wind generator revenue reductions $ 795M $ 960M Load payment reductions (calculated as product of hourly load and the corresponding locational spot price) $ 515M $ 720M Source: GE/NYSERDA Study Overview study -- 19

20 CA IAP Results 2007 Day-ahead unit commitment observations Economically rational unit commitment that includes intermittent resource forecasts results in sufficient flexibility for successful operation Forecasting increases value of intermittent resources by $4.37/MW-hr Load payment reduction is $2.91/MW-hr of load in CA 80% of the value of forecasting is obtained with state-ofthe-art forecasts Regulating reserve observations Incorporating hourly wind forecast into economic dispatch algorithm results in greatly reduced regulation offset and CPS2 violations Study Overview -- 20

21 Additional Studies of Note Recently Completed Ontario Hydro Manitoba Hydro Hydro Quebec SaskPower AESO Avista and Idaho Power Northwest Wind Integration Action Plan, Phase I California IAP Xcel/Colorado Underway or Nearing Completion Arizona Public Service Arizona Power Authority Nevada Power Sacramento Municipal Utility District Public Service New Mexico ERCOT Xcel/SPS Study Overview -- 21

22 Conceptual EHV Transmission Overlay Study Overview -- 22

23 Transmission Planning Recommendations Develop adequate transmission capacity Comprehensive regional planning processes Federal leadership in developing transmission in the national interest Reassessment of transmission financing approach Customers in remote regions can t afford it load pays in the end More certainty of transmission cost recovery More robust and flexible smart grid Study Overview -- 23

24 For More Information Visit Phone Fax Charlie Smith Mail Utility Wind Integration Group PO Box 2787 Reston, VA USA Study Overview -- 24