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OPNs

OPNs. Offtake Arrangement Workstream – OAD Section I Review Group 316. OPNs - Agenda. OPN processes – walkthrough process flow diagrams of OAD section I/UNC section J DN inputs DN processes that feed into OPNs Operational constraints NTS Processes

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OPNs

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  1. OPNs Offtake Arrangement Workstream – OAD Section I Review Group 316

  2. OPNs - Agenda • OPN processes – walkthrough process flow diagrams of OAD section I/UNC section J • DN inputs • DN processes that feed into OPNs • Operational constraints • NTS Processes • Overview of the NTS processes that currently feed off OPNs • NTS Manual work-arounds (including information on METGAS screen) • OPN accuracy • NTS Exit Reform (0195AV) Processes & NTS Risk Management tools  - short preview of session 2 (November 2nd 2010)

  3. OPN Usage

  4. Data Provision Definitions The rates of the offtake set out in the OPN shall reflect as accurately as reasonably practicable The quantities, rates and times at which the DNO intends /expects to flow. (OAD I 2.1.5 a)

  5. OPN Revision Requirements

  6. DN inputs

  7. Overview of the NTS processes that currently feed off OPNs

  8. Key times in the current system process LDZ Take Data (Metgas Screen) and previous days OPNs used in GNCC processes due to OPN accuracy / timing issues. • Demand Forecaster Run Times: • Day-1 • Calibration Runs • 13:00 • 16:00 • 24:00 • Day • Every hour after 06:00

  9. NTS Manual Workarounds – METGAS

  10. METGAS information • Forecast LDZ take provided by DNs via METGAS screens within GTMS • NTS ‘take’ = Demand Forecast + VLDMCs - (Interruption, LNG Boil Off, On Shore Fields) +/- Stock Change & Inter LDZ transfers • The METGAS screen provides a breakdown of the forecast NTS take, by LDZ and Total Take. It shows both within day and day ahead values and gives the time when the latest forecast was generated.

  11. METGAS information (1) – Demand Forecast • NTS Demand Forecast: • An NTS Total system demand forecast comprises of data from all offtakes, i.e. direct connects, interconnector, LDZs, etc • LDZ NTS take • OPF process will substitute (last approved from previous day) OPN data that is not provided

  12. METGAS information (2) – System balancing • National Grid NTS calculate Predicted Closing Line Pack (PCLP) and undertake balancing actions based on input and output information • Input Notifications from Delivery Facility Operators • Output Notifications provided to NTS by both Users (Direct Connects) & DNs respectively • For LDZ NTS take, NTS may use the following (depending on timing of PCLP calculation) • METGAS information • Offtake Profile Notifications

  13. OPN Accuracy & Timing

  14. Offtake Tolerances • OAD Section I • 3.1.2 • The tolerance, in respect of the offtake of gas at an Offtake is 10% of the prevailing offtake rate • 3.1.3 • The tolerance, in respect of the offtake of gas in aggregate at all of the Offtakes which serve an LDZ, is 3% of the aggregate of the Prevailing Offtake Rates.

  15. Proportion of OPNs breaching the 10% tolerance

  16. Distribution of Forecast Error by LDZ

  17. Distribution of Forecast Error by hour

  18. Evolution of Forecast Error over time from sample offtakes

  19. Summary • Evidence provided that some OPNs are outside of the 10% offtake tolerance and the 3% LDZ tolerance • DN OPN processes run later than NTS demand forecast round up times?

  20. Benefits associated with good quality OPNs (Current processes) • Continuous Improvement of Forecasting (Forecaster) • Enhanced Network Balancing • Physical • Safe Operation of the NTS • Efficient Use of the NTS • Delivery of Assured Pressures • Constraint management • Environmental Impact due to Compressor Usage • Reduced Emissions • Less Venting • Better energy procurement • Lower Cost to the community • Commercial • Efficient System Balancing Actions • Lower Cost to the Community • Better informs the Shippers balance position

  21. Preview of session 2 (November 2nd 2010)

  22. NTS Exit Reform/Risk Management Processes

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