PV Forecasting RFP Bill Blevins Sep. 24, 2014 Projected Installed Capacity of PV in ERCOT Projected Intalled Capacity of PV (MW) 4,000 3,500 3337 3,000 2,500 2214 2,000 1,500 1,000 500 325 0 2014 2015 2016 2 PV Short-term Forecast Value of solar forecasts to bulk power system reliability • To assist the balancing area operators in performing their duties • To enhance the economic efficiency and manage bulk power system reliability operational affects on the remainder of the generation fleet Key Features: • Address photovoltaics (PV) only • Centralized solar forecast • Benefits of size • Different forecasts for different uses and time periods • Next hours forecast • Next day forecast • Unbiased forecast typically the 50% POE (probability of exceedance) 3 Experiences with Wind Forecast at ERCOT and Potential Needs for PV Forecast Short Term Wind Power Forecast • Delivery: Hourly - 15 minutes after the hour (may change this) • Forecast period: rolling 48 hour ahead forecast • Forecast parameters for each WGR - Average hourly MW 50% POE MW (labeled as STWPF used for COP) 80% POE MW (labeled as WGRPP) 4 NPRR 615 PVGR Forecasting PVGRPP STPPF PVGR PhotoVoltaic Generation Resource Production Potential Short-Term PhotoVoltaic Power Forecast PhotoVoltaic Generation Resource Approved by Board of Directors on Aug. 12, 2014 5 Solar Power Forecast Challenge Factors that Affect Solar Power • • • • Global Solar Irradiance (~90%), Temperature (~10%), Wind (<1%) Type of Plant – Determines exact impact of all three factors – Categories of plants: (1) PV, (2) Concentrating PV, (3) Solar thermal (also concentrating) – PV is sensitive to Global Irradiance – Concentrating types (thermal and PV) are sensitive to Direct Normal Irradiance – Also significant sensitivity variations within basic categories 6 Making the Best Forecast for Various Time Scales Minutes Ahead • • • • • • Cumulus clouds, small-scale cloud structures, fog Rapid and erratic evolution; very short lifetimes Mostly not observed by current sensor network Tools: persistence, skycams, local irradiance trends Very difficult to beat a persistence forecast Need: Data & tools to handle development & dissipation Hours Ahead • Frontal bands, mesoscale bands, fog, thunderstorms • • • • Rapidly changing, short lifetimes Current sensors detect existence but not structure Tools: satellite-based cloud advection and NWP Need: Better forecasts of development & dissipation Days Ahead • • • • • • “Lows and Highs”, frontal systems Slowly evolving, long lifetimes Well observed with current sensor network Tools: NWP with statistical adjustments > ~ 10 days- climatology and climate trends Need: better NWP performance & improved MOS 7 Timelines of PV Forecasting RFP 7/23/2014 Optional Notice of Intend to Propose Due 7/16/2014 RFP release 09/30/2014 Vendor Presentations 08/18/2014 Vendor Proposals Due 12/01/2014 Anticipated Contract Award 01/01/2015 Anticipated Contract Start Date Proposed/ Current timeline. May be modified based on expected ability of respondents and ERCOT to complete necessary RFP evaluations. 8 Data Flow and Dependencies of Renewable Production (PVGR) Potential Forecast Market Information Systems (MIS) Secure Area MIS Certified Area RPP forecasts to QSEs STPPF/ PVGRPP Renewable Production Potential Forecast Supervisory Control and Data Acquisition (SCADA ) Mid-Term PV Generation Forecast Data from PV Generation Resources 9 PVGRs Telemetry Meteorological Data Points Element Plane of Array Irradiance Back Panel Temperature (Degree C) Air Temperature (Degrees Celsius) Device(s) Needed Pyranometer or Equivalent Temperature probe for back panel temperature Temperature probe & shield for ambient temp Anemometer, wind vane and wind mast Anemometer, wind vane and wind mast Wind Speed (Meter / Second) Wind Direction (Degrees - Zero North 90CW) Barometric Pressure Barometer (hecto Pascals) Units W/m² ⁰C ⁰C m/s Degrees hPA Plane of Array Irradiance (POA irradiance) is a measure of the total amount of solar energy that is available to an array, based the location of the array and the direction of the modules. POA irradiance is calculated at the module level, and averaged across modules to generate system-level values. 10 PVPF Process Inputs Source Registration system Data 1.           1. Energy Management System (EMS) Telemetry value Resource Parameters Resource Name Location of PVGR (latitude and longitude or equivalent for the center point of PVGR) Location of the meteorological station (latitude and longitude or equivalent) Type (manufacturer/model) and number of PV panels Panel Power Rating Number of inverters Inverter ratings Tracking/Single or Dual Axis Tracking Tracker Manufacturer Tracker Model Resource Commercial Operation Date 1. Most recent Resource (PVGR) status with date/time 2. Most recent MW output of PVGR with date/time 3. Most recent meteorological measurement from one meteorological station with date/time 4. Temperature and barometric pressure on the meteorological station SCADA telemetry values are sent every 5 minutes from EMS to the PV forecast service provider (all of these are Unit specific information with their Qualified Scheduling Entities (QSE) mapping) 1. MW Average 2. Wind Speed 3. Wind Direction 4. Temperature 5. Barometric Pressure 6. Back Panel Temperature(*) 7. Plane of Array Irradiance(*) 8. HSL Average 9. Num of Panels ON 10. Num of Panels Off 11. Num of Panels Unknown 12. Curtailment Flag 11 PV Forecasting RFP Requirement • STPPF/PVGRPP will be delivered to ERCOT hourly, providing a rolling 48-hour hourly forecast of production potential for each PVGR or the entire ERCOT systems • MTPVGF is an hourly forecast service for PVGR generation and the ERCOT system for the current day and the next 7 days. • The performance of PV forecasting is evaluated based on both accuracy and reliability MAE  1 N  N  pi  pi i 1 12 Progress on RFP • More than 60 questions were clarified • 8 respondents received in response to RFP • 6 proposals were selected for presentation to narrow down the participants in the RFP • ERCOT is identifying parties to provide presentations on their approach as the next step in commencing solar forecasting. 13 Bill Blevince Manager Operations Planning Electric Reliability Council of Texas, Inc. 2705 West Lake Drive Taylor, Texas 76574 Bill.Blevins@ercot.com 14