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Overview IDC – Interchange Distribution Calculator Market Flow Calculator

Overview IDC – Interchange Distribution Calculator Market Flow Calculator Revenue Uplift / Schedule Infeasibility CAT – Curtailment Adjustment Tool.

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Overview IDC – Interchange Distribution Calculator Market Flow Calculator

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  1. Overview • IDC – Interchange Distribution Calculator • Market Flow Calculator • Revenue Uplift / Schedule Infeasibility • CAT – Curtailment Adjustment Tool

  2. LODF = Line Outage Distribution Factor indicated % of the flow of the Contingency element that will end up on Monitored element if Contingency trips. Every flowgate has a rating provided by owner of the monitored element. Rating is called SOL (System Operating Limit).NERC Standards require action by RC to maintain flow of flowgate below SOL limit. Some flowgates have a second rating that is called IROL. Those flowgates are critical facilities and if they trip can cause cascade outages. The IROL limit is calculated by off line stability studies.NERC Standards require action if flowgate flow > IROL limit and relief need to be provided within 30 minutes. What is a flowgate?

  3. Elements of a Flowgate • A Flowgate is either a PTDF or OTDF type • PTDF is a Power Transfer Distribution Flowgate that is typically controlling monitored transmission elements to a total real-time flow • OTDF is an Outage Transfer Distribution Flowgate that is controlling transmission elements in a ‘what-if’ n-1 situation; The Reliability Coordinator controls the flowgate of a monitored element such that if a contingent element trips, the element monitored is not overloaded

  4. PTDF Flowgate Example • A collection of Transmission system elements grouped together and controlled to a collective rating • Flowgate examples: SPPSPSTIES, SPSSPPTIES, GENTLMREDWIL

  5. OTDF Flowgate Example • What if situation: one line for the loss of another; for example: LAKALASTJHAW • Lake Road -> Alabama 161kV ftlo St Joe -> Hawthorn 345kV • If the contingent element trips, a portion (0-100%) of the power flows onto the monitored element • Classic n-1 contingency; most flowgates fall in this category

  6. Permanent & Temporary Flowgates • Permanent Flowgates are previously identified constrained paths on the SPP Transmission system as well as external areas to SPP that may be impacted by SPP serving load • Temporary Flowgates are built ‘on-the-fly’ to control the unknown or short-term issues • These may be due to planned or unplanned outages • Unforeseen loading may cause a temporary

  7. Monitoring Real Time loading of flowgates Real Time loading flowgate

  8. IDC/CAT Curtailment / Adjustment Responsibilities • NERC IDC Curtailments based on TDF (Gen to Gen) • Tagged Interchange Transactions that leave or enter SPP Market footprint. • Tagged Interchange Transactions from Self-Dispatched units • Other Tagged Transactions external to SPP • Network and Native Load (NNL) external to SPP market footprint • Market Flow • SPP CAT Curtailments/Adjustments based on GLDF (Gen to Load) • Tagged Interchange Transactions from units that are not Self-Dispatched. (Inter Control Area) • Intra-BA Schedules from Market-Dispatched units (NLS or Tagged) • Intra-BA Schedules from Self-Dispatched units (NLS or Tagged)

  9. Interchange Distribution Calculator

  10. History of NERC and NERC Standards • IRO-006-4 Reliability Coordination — Transmission Loading Relief • IDC Background • IDC Inputs • TLR Levels • IDC Factors

  11. Transmission Loading Relief (TLR) • The Reliability Coordinators of the Eastern Interconnect use a Transmission Loading Relief tool that is called NERC IDC. • In case of an overload on the Eastern Interconnect Transmission System, a Reliability Coordinator can call a Transmission Loading Relief (TLR) event on NERC IDC. • The Transmission Loading Relief (TLR) event triggers a calculation by NERC IDC Software that results in: • Tag curtailments assigned to Tags and Schedules that have more than 5% impact on the constrained facility that is in TLR • Market Flow relief assigned to the SPP Market, MISO Market and PJM Market if they impact the constrained facility. • NNL Obligation assigned to Non-Market Balancing Authorities that require them to re-dispatch generation to accomplish the assigned relief amount. • NERC IDC will send out the curtailment and relief information to the Etagging Systems and other Systems of Reliability Coordinators.

  12. NERC Links • NERC’s Website • http://www.nerc.com/ • NERC Reliability Standards • http://www.nerc.com/page.php?cid=2|20 • FERC Approved Standards • http://www.nerc.com/filez/standards/Mandatory_Effective_Dates_National_Energy_Board.html

  13. Standard IRO-006-4 — Reliability Coordination — Transmission Loading Relief • A. Introduction • 1. Title: Reliability Coordination — Transmission Loading Relief (TLR) • 2. Number: IRO-006-4 • 3. Purpose: The purpose of this standard is to provide Interconnection-wide transmission loading relief procedures that can be used to prevent or manage potential or actual SOL and IROL violations to maintain reliability of the Bulk Electric System. • 4. Applicability: 4.1. Reliability Coordinators. 4.2. Transmission Operators. 4.3. Balancing Authorities.

  14. NERC Standard IRO-006-4 TLR • R1. A Reliability Coordinator experiencing a potential or actual SOL or IROL violation within its Reliability Coordinator Area shall, with its authority and at its discretion, select one or more procedures to provide transmission loading relief. These procedures can be a “local” (regional, interregional, or sub-regional) transmission loading relief procedure or one of the following Interconnection-wide procedures

  15. NERC Standard IRO-006-4 TLR • R1.1. The Interconnection-wide Transmission Loading Relief (TLR) procedure for use in the Eastern Interconnection provided in Attachment 1-IRO-006-4. The TLR procedure alone is an inappropriate and ineffective tool to mitigate an IROL violation due to the time required to implement the procedure. Other acceptable and more effective procedures to mitigate actual IROL violations include: reconfiguration, redispatch, or load shedding

  16. NERC Standard IRO-006-4 TLR • R3. Each Reliability Coordinator with a relief obligation from an Interconnection-wide procedure shall follow the curtailments as directed by the Interconnection-wide procedure. A Reliability Coordinator desiring to use a local procedure as a substitute for curtailments as directed by the Interconnection-wide procedure shall obtain prior approval of the local procedure from the ERO.

  17. NERC Standard IRO-006-4 TLR • R4. When Interconnection-wide procedures are implemented to curtail Interchange Transactions that cross an Interconnection boundary, each Reliability Coordinator shall comply with the provisions of the Interconnection-wide procedure.

  18. Interchange Distribution Calculator • IDC was created to implement the TLR process explained in IRO-006 Attachment 1 • Procedures for curtailment and reloading of Interchange Transaction to relieve overloads on transmission facilities modeled in the IDC • IDC is a NERC Tool for the Eastern Interconnect • The IDCWG is a NERC working group that is responsible for implementing IDC and other tools in support of the NERC RC’s. • The IDCWG reports to the Operating Reliability Subcommittee (ORS)

  19. Inputs to IDC • Monthly Model developed by the IDCWG • System Data Exchange (SDX) every 20 minutes • eTag • Marginal Zones from PJM (every 5 min) and MISO (quarterly) **Not used** • Market Flow SPP/PJM/MISO • Phase shifter Tap settings

  20. TLR Levels • TLR Level 1 — Notify Reliability Coordinators of potential SOL or IROL Violations • TLR Level 2 — Hold transfers at present level to prevent SOL or IROL Violations • TLR Level 3a — Reallocation of Transmission Service by curtailing Interchange Transactions using Non-firm Point-to-Point Transmission Service to allow Interchange Transactions using higher priority Transmission Service • TLR Level 3b — Curtail Interchange Transactions using Non-Firm Transmission Service Arrangements to mitigate a SOL or IROL Violation

  21. TLR Levels Continued • TLR Level 4 — Reconfigure Transmission • TLR Level 5a — Reallocation of Transmission Service by curtailing Interchange Transactions using Firm Point-to-Point Transmission Service on a pro rata basis to allow additional Interchange Transactions using Firm Point-to-Point Transmission Service • TLR Level 5b — Curtail Interchange Transactions using Firm Point-to-Point Transmission Service to mitigate an SOL or IROL violation • TLR Level 6 — Emergency Procedures • TLR Level 0 — TLR concluded

  22. What is a Schedule? • A schedule represents a physical transaction on the Transmission System between a Source and a Sink. • All schedules that cross BA boundaries require a Tag in the Etagging System of the Eastern Interconnect. (Source and Sink of the schedule are in different Balancing Authority Areas). • Schedules typically have an hourly profile, although it is possible to have 5 minute granularity. • A Balancing Authority will add up all import and export schedules from its Control Area to determine the Net Scheduled Interchange value (NSI value) for a particular hour for his BA area. • Tags / Schedules need to be submitted at least 20 minutes and in some cases 30 minutes before they are supposed to be flowing

  23. How a Schedule is created? • Confirmed TSR (Transmission Service Request) on the transmission system for full path of the intended Schedule / Tag. • The Transmission Rights and TAG on the approved path may be used by customer between the Source BA and Sink BA. • The schedules are then created in E-Tag System and other SPP scheduling System (RTOSS) • Scheduling systems (RTOSS for SPP) validates the Schedule against Transmission Rights and approve the schedule. • Net Scheduled Interchange for a BA is calculated from the set of schedules that is available in the Scheduling System.

  24. Priority of Transmission Rights determine sequence of curtailing in case of an over load situation that required calling TLR on NERC IDC • Secondary Non-Firm (late redirect from Firm) NS1 • Non-Firm PTP Hourly NH2 • Non Firm PTP Daily ND3 • Non Firm PTP Weekly NW4 • Non Firm PTP Monthly NM5 • Non Firm Network (Non-designated) NN6Voluntarily dispatch before going to TLR Level 5 • Firm PTP (All) F7 • Firm Network (designated Resources) NF7(accomplished by re-dispatching Units) • Load shedding TLR Level 3 TLR Level 4 TLR Level 5

  25. How is the priority of schedules determined • Schedule priority is determined by the priority of the TSR (Transmission Service Right) purchased by the Transmission customer. • The higher the priority the more the schedules are “protected” against curtailments by NERC IDC and CAT in case of a TLR event.

  26. Introduction to IDC Factors • TDF –Transfer Distribution Factor • GSF –Generation Shift Factor • LSF –Load Shift Factor • GLDF –Generation-to-Load Distribution Factor • LODF –Line Outage Distribution Factor • PTDF & OTDF Flowgates

  27. Transfer Distribution Factors • Transfer Distribution Factors (TDF’s) represent the impact of an Interchange Transaction on a given flowgate. • TDF is the measure of responsiveness or change in electrical loading on system facilities due to a change in electric power transfer from one area to another expressed in percent (up to 100%) of the change in power transfer. • TDFs address the question, “What portion of a power transfer shows up on flowgate X?”

  28. TDFs used in the IDC • TDFs are used to determine which Interchange Transactions are eligible for TLR curtailment in the IDC. • Only those Interchange Transactions with a TDF of 5% or greater are subject to TLR Curtailments. • If a tag indicates a TDF of 8.3% on flowgate X, this means that 8.3% of the transfer amount on that tag flows on flowgate X. • Use the following formula to calculate the MW impact on a flowgate for a particular Interchange Transaction: MW impact = (Interchange transaction MW) x (TDF)

  29. Generation Shift Factors • Generation Shift Factors (GSF) describe a generator’s impact on a flowgate • The Generation Shift Factors (GSF) represent the change in flow on a flowgate due to an incremental injection at a generator bus, and a corresponding withdrawal at the swing bus • IDC disregards losses ⇒the principles of superposition applies. • GSF between any two generators is the difference between the generators’ GSF to the swing bus • GSFk→m= GSFk→swing–GSFm→swing

  30. GSF Used in the IDC • GSFs are the most basic IDC calculation –used in TDF calculations (all TLR levels) and GLDF calculations (TLR level 5) • GSFs on the Flowgate GSF display in the IDC indicate which generators contribute to or relieve congestion on a selected flowgate. • If a generator indicates a GSF of 10% on flowgate X, this means that 10% of the generator’s output flows on flowgate X, provided the injection is withdrawn at the swing bus • Use the following formula to calculate the MW impact on a flowgate for a particular generator: • MW impact = (Gen MW) x (GSF)

  31. Load Shift Factors • Load Shift Factors (LSF) describe how changes in system loading impacts a flowgate.

  32. LSF Used in the IDC? • LSFs are used to calculate GLDFs, which are used to determine NNL obligations under a TLR Level 5. • LSFs are shown along with GSFs on the GLDF displays in the the IDC. • The LSFs alone are not used by the IDC – the LSF is a component of the Generation-to-Load Distribution Factor (GLDF)

  33. Generation-to-Load Distribution Factors • Generation-to-Load Distribution Factors (GLDF) describe a generator’s impact on a flowgate while serving load in that generator’s Balancing Authority Area • A GLDF is the difference between GSF and an LSF and determines the total impact of a generator serving its native Balancing Authority load on an identified monitored flowgate.

  34. GLDF Used in the IDC • GLDFs are used to determine NNL obligations under a TLR Level 5. • Only those generators with a GLDF of 5% or greater are subject to NNL obligations. • GLDFs are shown in the Flowgate GLDF display and the CA GLDF display in the IDC. • In the Flowgate GLDF display the user selects a flowgate and is shown a list of generators that contribute to flow as a byproduct of serving their own Balancing Authority Area load (i.e., the NNL impact). • In the CA GLDF display, the user is shown a listing of flowgates that are impacted by generators serving their own Balancing Authority Area load.

  35. GLDF Used in the IDC Continued • Use the following formula to calculate the NNL MW impact on a flowgate for a particular generator: • NNL MW impact = (Scaled MW) x (GLDF) x (% ownership) • Scaled MW is calculated according to the following formula: Scaled MW = (Load / Available Assigned Generation) x (Pmax) • If a generator indicates a GLDF of 9.7% on flowgate X, this means that 9.7% of the generator’s output flows on flowgate X as a byproduct of serving Balancing Authority Area native load. • The GLDF is calculated according to the following formula: • GLDF = GSF -LSF

  36. Line Outage Distribution Factor (LODF) • Line Outage Distribution Factor (LODF) represents the percentage of flow on a contingent facility that will flow on the monitored elements, if the contingent facility is outaged–Contingency Analysis • Post-Contingency Flow on Monitored Element = Pre-Contingency Flow on Monitored Element + (Pre-Contingency Flow on Contingent Element)*LODF • LODFs are not used in IDC TLR calculations

  37. PTDF & OTDF Flowgates • PTDF –Power Transfer Distribution Factor. PTDF Flowgates are Flowgates that do not consider contingencies during curtailment evaluation. With PTDF Flowgates the monitored branches alone are considered during evaluation. • OTDF –Outage Transfer Distribution Factor. OTDF Flowgates are Flowgates that take into account a predefined contingency during curtailment evaluation. With OTDF Flowgates the monitored branches are considered with a specific facility removed from service during evaluation.

  38. How are GSF, TDF, LSF and GLDF Calculated in the IDC? • All factors (GSF, TDF, LSF) are calculated from a master shift factor matrix of each bus and each flowgate every 20 min • This matrix is calculated by simulating an incremental injection in every bus (individually, one at a time) and a corresponding withdrawal at the swing bus. The term is loosely called GSF even though it is calculated for every bus, regardless of being attached to a generator. • The Balancing Authority’s TDFs are calculated as the weighted sum of the GSFs in a Balancing Authority Area for every in-service generator –the weighting factors are the generators’ MBASE in the PSSE base case model, adjusted for de-ration as provided via the SDX • TDF = Σ( GSF x MBASE x DE-RATION ) / Σ( MBASE x DE-RATION ) • The Balancing Authority’s LSFs are calculated as the weighted sum of the GSFs in a Balancing Authority Area for every connected load bus as defined in the PSSE base case –the weighting factors are the load MW amount on the buses. • LSF = SUM( GSF x LOAD ) / SUM( LOAD )

  39. How are GSF, TDF, LSF and GLDF Calculated in the IDC? • The TDF between two Balancing Authority Areas is the difference between the TDFs of the Balancing Authority Areas (principle of superposition): • TDFBA1 –BA2= TDFBA1–TDFBA2 • The TDF of a tag is the TDF between the source and sink Control Areas • TDFTag= TDFSourceBA–SinkBA= TDFSourceBA–TDFSinkBA • Tag path: • Every tag has a defined path: Source BA –TP1–TP2–…–TPn–Sink BA • The TDF of a tag is the sum of the TDFs of every segment on a tag –which is equivalent to the TDF between the source and sink BA: Segment 1:TDFSourceBA–TP1= TDFSourceBA–TDFTP1 Segment 2:TDFTP1–TP2= TDFTP1–TDFTP2 Last Segment:TDFTPn–SinkBA= TDFTPn–TDFSinkBA TDFTag= TDFSourceBA–TDFTP1+ TDFTP1–TDFTP2+ TDFTP2–TDFTP3+ …+ TDFTPn–TDFSinkBA= TDFSourceBA–TDFSinkBA

  40. How are GSF, TDF, LSF and GLDF Calculated in the IDC? • Tag path (continued): • Special case –segmented tag, or tags through controlled devices (phase shifters and DC ties): • 100% of the tag scheduled MW flows through the controlled device • TDF of tag is the sum of the TDF between the Source BA and the entry point to the controlled device, and the TDF between the exit point of the controlled device and the sink BA. • Example: • Tag 1 –segmented through DC/phase shifter: TDFTag1= TDFBA1–P1+ TDFP2–TDFBA2 • Tag 2 –AC tag between BA-1 and BA-2: TDFTag2= TDFBA1–TDFBA2 • TDFTag1≠TDFTag2 • See diagram on the following slide

  41. Transmission Service Priorities • Priority 0. Next-hour Market Service — NX* • Priority 1. Service over secondary receipt and delivery points — NS • Priority 2. Non-Firm Point-to-Point Hourly Service — NH • Priority 3. Non-Firm Point-to-Point Daily Service — ND • Priority 4. Non-Firm Point-to-Point Weekly Service — NW • Priority 5. Non-Firm Point-to-Point Monthly Service — NM • Priority 6. Network Integration Transmission Service from sources not designated as network resources — NN • Priority 7. Firm Point-to-Point Transmission Service — F and Network Integration Transmission Service from Designated Resources —FN

  42. Con’t • IDC Curtails on a pro-rata basis starting with the lowest service priority • Non Firm Service levels 0-6 • Firm Service level 7

  43. Example TLR 5 • 4 Firm Schedules (total of 400MW) • 3200 MW of generation serving Load within BA • RC Relief Requested 100MW on FG X. • IDC calculates relief as: • Total schedule Impact divided by (Total schedule impact + Total NNL impact). SI / (SI + NNL) • In this example there is no non firm interchange tags that have a TDF 5% or greater

  44. Example TLR 5 • TagsMWTDF%Total Schedule Impact on FG • A 100 10 10 • B 100 20 20 • C 150 5 7.5 • D 50 15 7.5 • Total 400 45 • GenMWGLDF%Total NNL Impact on FG • A 1500 8 120 • B 500 15 75 • C 400 5 20 • D 800 10 80 • Total 3200 295

  45. ExampleTLR 5 • In this example, the relief would be distributed by the above mentioned equation. • 45 / (45+295) which = 13%. • 13% * 100 = 13MW of relief from schedules. • The remaining 87MW of relief will come from NNL. • This 13 MW of relief from schedules is then distributed among all the schedules based on their TDF’s using the following equation: • ([Relief required] * [TDF] * [Tag MW]) divided by ([Sum of TDF^2] * [Tag MW]). Using the example schedules above in the calculation you will see how it is distributed.

  46. ([Relief required] * [TDF] * [Tag MW]) divided by ([Sum of TDF^2] * [Tag MW]) • Relief required = 13MW • ([Sum of TDF^2] * [Tag MW]) = (.1)^2(100) + (.2)^2(100) + (.05)^2(150) + (.15)^2(50) = 6.5 • Using the equation: • Tag A = (13(.1)(100))/6.5 = 20 • Tag B = (13(.2)(100))/6.5 = 40 • Tag C = (13(.05)(150))/6.5 = 15

  47. Therefore, 20mw would be curtailed from tag A, if you multiple that by .1 TDF you will get 2 mws relief. Tag B would provide 8 mws relief, tag C would provide .75 mws relief and tag D would provide 2.25 mws relief. This relief added together will result in 13 mws relief on the FG. Therefore, it took 90 MWs of schedule curtailments to provide the 13 mws of relief on the FG. The remaining 87MW of relief would have to come from NNL obligations.

  48. Re-Cap of NERC IDC logic • Reliability Coordinator (RC) issues (or re-issues) a TLR on a flowgate • When RC issues TLR event he enters the TLR Level (1, 2, 3A, 3B, 4, 5A, 5B) • 3A is Next hour Non Firm Curtailments • 3B is Current hour Non Firm Curtailments • 5A is Next hour Firm Curtailments • 5B is Current hour Non Firm Curtailments • When RC issues TLR he enters value for Operator Flow Change Request. (negative is asking for more curtailments and lower Market flow Target) • NERC IDC calculates required curtailments and Market Flow Target • NERC IDC is sending results to SPP CAT, SPP Constraint Manager and Etagging System

  49. SPP Congestion Management Tools

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