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Flowgate DefinitionConsists of a group of transmission elements that have been defined as a potential for congestion due to Thermal, Reliability and/or Stability concerns.Can Be Created Using Two Methods:� PTDF: Flowgate exists due to a pre-
contingent scenario and looks for relief on the monitored elements prior to a planned outage event
� OTDF: Flowgate exists due to a post-contingent scenario and looks for relief on the monitored element while simulating the contingency
Flowgate Definition
Elements of a Flowgate:- Monitored Element(s) : Power System
Element(s) that requires MW relief- Contingent Element(s) : Power System
Element that will have an action that causes the monitored element to become congested and/or unreliable (i.e. taking an element out of service) (OTDF Only)
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Flowgate Definition
- Total Transfer Capability (TTC)- The amount of MW flow that can occur on the
flowgate due to the limitation it defines.- Transfer Reliability Margin (TRM)
- The amount of MWs that must be reserved on the flowgate to protect against the next contingency, reserve sharing agreements, and uncertainties (load forecast etc.)
- Capacity Benefit Margin (CBM)- The amount of MW capability that is reserved by
the transmission provider for load-serving entities, whose loads are located on the transmission provider’s system
Flowgate Example
NPPD (B)
WAPA (A) MISO (C)
SWPP (D)
1
2
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Flowgate: West East 1Monitored: Element 3 and 4Contingent: None
Flowgate West Voltage 1Monitored: Element 1Contingent: Element 2
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Flowgates
NERC manages a central repository of the Flowgate Definitions for the Eastern Interconnect: Book of Flowgates (BoF)The BoF is updated by all NERC Reliability Coordination Regions and is used in Congestion Management and AFC procedures for the Eastern Interconnect.
AFC and ATC
The transfer capability remaining in the physical transmission network for further commercial activity over and above already committed uses.
� Available Transfer Capability (ATC)-SWPP� Available Flowgate Transfer Capacity (AFC)-MISO
Several methodologies exist to perform these calculations (i.e. assumptions and data used)
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JOA Flowgate Coordination
Problem: Flowgates are in TLR Solution: Mitigate overselling of Flowgates in the AFC/ATC realm. Increase accuracy of Congestion Management to create more efficient relief.
JOA Flowgate Coordination
Main Steps:� Allocate capacity of the defined Flowgates
between JOA parties for coordination� Adhere to this allocation of capacity when selling
transmission service. Don’t oversell your portion of the flowgate
� Act to remove excess MW flow on Flowgates in real time by re-dispatching back to agreed to base usage based on Market Rules and NERC Transmission Loading Relief Procedure
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JOA Flowgate Coordination
Flowgates that will be defined for Allocation will be defined in three categories:� Coordinated
� List of Flowgates that an individual party has system impact on
� Reciprocal� List of Flowgates that two or more parties have system
impact on
� Other� List of Flowgates that no entities have significant impact
on
JOA Flowgate Coordination
Having ‘System Impact’ is defined:� A case where the JOA Party’s power system is
affecting a Flowgate by any of the following means:� System Generation to Load impact by 5% or more� (N-1) Contingency impact by 3% or higher� Control Area to Control Area transfer Impact by 5% or
higher
� Meeting any of these criteria assigns the Flowgate as ‘Coordinated’ for the JOA Party
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JOA Flowgate Coordination
Each Party’s Coordinated Flowgates are compared with the other JOA participant lists, if a Flowgate exists on one or more lists the Flowgate becomes ‘Reciprocal’ for the entities.
Reciprocal Flowgates will always participate in AFC/ATC and congestion management coordination between the JOA parties
MISO Coordinated Flowgates (By NERC Region, Includes MISO Internal Facilities)
SPP- 43
ECAR- 182
MAIN- 276
MAPP- 110
SERC- 98NPCC- 13
MAAC- 54
43182
276
110
98
13
54
MISO Total - 776
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JOA Flowgate CoordinationAllocation
Allocation process is set up to recognize historic dispatch patterns to establish historic flows on an interfaceThese historic dispatch patterns are established based on the system as of a “freeze date” of June 3, 2003� Uses designated resources as of the freeze date� Uses firm reservations that were confirmed prior
to the freeze dateJOA Parties are given “credit” for their flows based on the historic dispatch pattern
JOA Flowgate Coordination
Two main portions of FG Allocation� Generation to Load- Projected� Point to Point- HistoricalPoint to Point is done using a static list of reservations as of the Freeze DateGeneration to Load is done using variables for outages and load for the time period being projected
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JOA Flowgate CoordinationAllocation
Allocation of Flowgates is a dynamic process that is ran at five critical points in time with respect to a Flowgate:� “Seasonal” –Bi-annual run that that looks to months 6
through 18 into the future� Reciprocal Party Historic Impact % defined
� “Monthly” – Six Months into the future � “Weekly” – One week into future� “Two Day Ahead”- Two days into future
� Sets the Firm Market Flow Limit on a Flowgate for Congestion Management
� “Daily”- Current Day for 24 hours� Sets the Non-Firm Priority 6 Market Flow components on
a Flowgate for use in Congestion Management
JOA Flowgate CoordinationAllocation
Allocation is assigned for all Reciprocal EntitiesSeasonal Run sets the initial Flowgate AllocationSubsequent “runs” of the allocation process may change the allocation, but not the Historic impact percentageThe historic ratio is defined as the ratio of the company’s impact to all companies’ impacts
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JOA Flowgate CoordinationAllocation
Allocation for an JOA Reciprocal Entity will not be decreased in value for any given RunA portion of the Flowgate Capacity is reserved for potential additional Reciprocal Entities. � This is defined as an ‘Expansion Margin’ for the Flowgate� The ‘Expansion Margin’ is released for a Flowgate 6 months
prior to the current day if additional entities have not indicated they will be pursuing a Reciprocal relationship with the JOA entity
JOA Flowgate CoordinationAllocation
Historical Flows are Identified and Allocated with two components:� Generation to Load (GLD)
� Based on Historic Designated Resource Generator Set� Combined with necessary data: PSSE Model (GLD
Factors), Outages, Generation Merit Order, and Load Forecast
� Historical Point to Point� Based on Historic Reservation Set- from Freeze Date
� Combined with necessary data: PSSE Model (point-to-point impacts), Outages
� Credit assigned based on detailed rules� Imports, Export, and Wheels treated differently� “Owner” of Flowgate accounted for
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NERC OC FEB ‘03
Calculating the Generation to Load Flow
Therefore …
Market Flow across Flowgate “A”: (20) + (7.5)+ (-6)
= 21.5 MWTherefore …
Generation to Load forFlowgate “A”:
(20) + (7.5)(-6)
= 27.5 MW Forward
Swing Bus
Load Busses
Generation Bus #1
GSF1 = .50 GSF3 = -.10
LSF = .10
Generation Bus #3
GSF = Generation Shift FactorImpact on Flowgate “A” from Individual Generator to Swing Bus
LSF = Load Shift Factor Impact on Flowgate “A” from Swing Bus to All Load
Flowgate“A”
MISO
SPP
MAPP
50 MW50
MW50
MW50
MW30
MW30
MW
10 MW10
MW50
MW50
MW70
MW70
MW
GLDF = Algebraic Sum of GSF – LSF
Therefore …
GSF1 – LSF = .5 - .1 = .4
GSF2 – LSF = .25 - .1 = .15
GSF3 – LSF = ( -.1) - .1 = (-.2)
Therefore …GLDF1 = .4 x 50MW = 20 MW Impact
GLDF2 = .15 x 50MW = 7.5 MW Impact
GLDF3 = (-.2) x 30MW = -6 MW Impact
= -6 MW Reverse(27.5) 21.5 MW Net+ (-6) =
GSF2 = .25
Generation Bus #2
Point to Point Impacts
Based on� Firm Reservations Confirmed (filtered and credited
using special methodology) as of June 3rd, 2003 Freeze Date� Filtering eliminates duplicate legs� Crediting assigns impacts based on source, sink, and
provider
� Impacts for the Point to Point Reservations are calculated for the time period of the allocation� Uses current IDC model� Uses current outages
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Point to Point Impacts
Customized List for each TP� Begin with all reservations on that TP’s node (the
primary provider’s node)� Add reservations from 1st Tier TPs that are NOT
“wheel throughs” and do NOT Source or Sink in the primary provider’s service territory
� Continue to 2nd tier, excluding “wheel throughs” and reservations that sink in the primary provider’s or the 1st Tier TPs’ service territories
� Continue until all appropriate TPs have been considered
Point to Point Impacts
For each flowgate, determine the “owner” and use their filtered reservation list For each reservation in the list� If it is a Import or Export, split the impacts
50/50 between the Source and Sink TPs� If it is a “wheel through,” split the impacts
25/50/25 between the Source, Wheeling, and Sink TPs
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JOA Flowgate CoordinationAllocation
Point-to-Point and Generation to Load sorted into two categories for the forward and reverse direction of the Flowgate:� A. Impacts Greater Than/Equal To 5%
� (GLD + Pt-to-Pt)� B. Impacts Less Than 5%
� (GLD + Pt-to-Pt)
Flowgate Limit Definition is Determined� Limit = TTC-CBM-TRM
Allocation steps are taken to assign Flowgate Capacity to each JOA entity for all Reciprocal Flowgates in both the Forward and Reverse direction
JOA Flowgate CoordinationAllocation
Three Main Allocation Steps� A. Impacts Greater Than/Equal To 5%
� All entities are granted a share of the flowgate equivalent to their flows based on impacts of 5% or greater
� B. Impacts Less Than 5%� If, after step A, there is still unclaimed flowgate capability,
Reciprocal entities are granted a pro rata share (based on their<5% impacts) of that capability up to the sum of their <5% impacts
� C. Additional Flowgate Capability� If, after step B, there is still unclaimed flowgate capability,
Reciprocal Entities are granted a pro rata share (based on theirhistoric impact percentage) of that capability.
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Allocation Example #1Seasonal Run
See Handout- Insertion- Four ExamplesFlowgate “East-West” - Seasonal Allocation� Reciprocal Flowgate Between SWPP and MISO� Flowgate Components:
� TTC= 700 MW� TRM= 200 MW� CBM = 100 MW
� Flowgate Limit for Allocation = 400 MW� TTC-TRM-CBM
C. Finally, share the remaining MW based on the Historic Ratio[Remaining Room *Historical %]SWPP= 100MW X (130MW/300MW) = 43MWMISO = 100MW X (170MW/300MW) = 57MW
Allocation Example #1Seasonal Run
TOTAL ALLOCATIONS :Seasonal Run for Flowgate “East-West”:
SWPP = 100MW + 30MW + 43MW = 173MW
MISO = 100MW + 70MW + 57MW = 227MWOther = 0 MW
173MW + 227MW +0MW = 400MW (FG Limit)Expansion Margin = 0 (<5% + Extra MW Added for Other)
*Due to Other Entities having Zero Impact on FG
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Allocation Example #2Seasonal Run
Flowgate “North #1” - Seasonal Allocation� Reciprocal Flowgate Between SWPP and MISO� Flowgate Components:
� TTC= 400MW� TRM= 125 MW� CBM = 25 MW
� Flowgate Limit for Allocation = 250 MW� TTC-TRM-CBM
C. Finally, share the remaining MW based on the Historic Ratio[Remaining Room *Historical % of Reciprocal Entities]
SWPP= 125MW X (80MW/175MW) = 57MWMISO = 125MW X (95MW/175MW) = 68MW
*Expansion Margin is now Zero
Allocation Example #4Monthly Run
TOTAL ALLOCATIONS For Monthly Run:[>5% Impacts + <5% Impacts +Extra Room]
SWPP = 50MW + 30MW + 57MW = 137MW
MISO = 25MW + 70MW + 68MW = 163MW
Other = 100 MW + 0MW + 0MW =100 MW
137MW + 163MW +100MW = 400MW (FG Limit)Expansion Margin = 0 MW*(<5% + Extra MW Added for Other)
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Allocation Example #4
Compare Allocations to Seasonal Run to ensure no Allocations are reduced for the Reciprocal EntitiesSWPP� Seasonal = 105 MW� Monthly = 137 MW
MISO� Seasonal = 124 MW� Monthly = 163 MW
JOA Flowgate CoordinationAdhere
Once the Flowgate Allocation is determined for a time period. The Reciprocal entity will use this value to determine if they can utilize more of the Flowgate Capacity while operating the power system for that time period
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JOA Flowgate CoordinationAdhere
AFC/ATC process will have two components• Reciprocal Allocation Check – verifies entities are
staying within their allocation limits• Reliability Check – verifies system is not being oversold
The AFC/ATC process will use the lowest of these two numbers when deciding to grant transmission serviceIf Reciprocal Allocation Check is lower, then entity will be bound to their shareIf Reliability Check is lower, entity will be bound to reliability limitsThe Reliability Check utilizes the existing AFC/ATC processes
Reciprocal Allocation CheckBegin with the AllocationSubtract net estimate of forecast Gen to Load impacts (down to 0%)Subtract impacts of sold PTP reservations in the forward direction (down to 0%)Add 15% of the impacts of counter flowing PTP reservationsRemainder is Available Share of Total Flowgate Capability
*Reciprocal Entity Not Utilizing more than the assigned allocation- continue
lli
MW
MWMW
MWMWMW
27
)45%(1558
2042100
+−
−−
JOA Flowgate CoordinationMarket Flow
When approaching near real time Market Entities that are Reciprocal Parties will be required to submit real time Market Flow information for Regional Congestion Management– Current/Next HourMarket Flow is the summation of the impact of the market generation (at current output) on a Flowgate for a given time period� MF = Current Gen MW* GLD Factor – (Pt-Pt Transactions)� Summed for all generation in the market footprint
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JOA Flowgate CoordinationMarket Flow
Market Flow is communicated as three components:� Firm Network = Historic NNL � Non-Firm Priority 6- (ED-6)� Non-Firm Priority 2- (ED-2)
This priority is used during Regional Congestion Management procedures (NERC TLR)
JOA Flowgate CoordinationMarket Flow
Determination of the Market Flow components:� Firm Network= Historic NNL
� Two Day Ahead NNL sets the Firm Market Flow Limit� If real time Market Generation impact on the Flowgate is less
than than this limit all Market Flow is considered Firm Network� ED-6
� Initial ED-6 limit is set during the Daily Run by comparing the estimated Daily allocation with the Two Day Ahead NNL.
� Any excess allocation will be put into the ED-6 bucket and sets the ED-6 limit for the FG
� ED-2� Any real-time calculated Market Flow Above the ED-6 value on
a Flowgate will be put into the Priority 2 category
Market Entities Plan to use TLR in conjunction with Market Re-Dispatch(LMP) relieve constraints in the regionMore Real-Time Data in TLR Process� Market Flow� Marginal Units
Market Flow will be curtailed along side of Non-Firm and Firm Point to Point Transactions
JOA Reciprocal Parties Should � Allocate Flowgates� Adhere to the Allocations� Act on Congestion
Questions?
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Enhancements Under Consideration
TRM and CBM MarginsSystem Expansion50% Point to Point Impacts on ASTFC3rd Party AllocationsTreatment of Unused Allocation
Allocation Special Topics
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TRM and CBM Margins
Currently, deduct TRM and CBM from the total flowgate rating prior to determining the allocationPropose to remove the CBM component from allocation calculationTP can use whatever CBM they feel appropriate for their share of allocation
System ExpansionCMP has a specific freeze date on transactions and generationUse same freeze date for network topology changesBenefits of transmission enhancements accrue to the TP responsible for the enhancementTransmission enhancements made after the freeze date excluded from allocation process
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Implement 50% Point to Point Impacts
When request involves another TP to complete the party, allocation required for only 50% impacts
Third Party Participationin AllocationCurrently hold an expansion margin for third parties beyond 6 monthsDoes this provide proper incentive to participate?Currently include third party flowgates in allocationDoes this provide proper incentive to participate?
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Treatment of Unused Allocation Between MISO and SPP
Unused allocation issue is where either MISO or SPP are restricted due to lack of an allocation while other party still has an unused allocationMISO and SPP will address two situations where this occursFirst: To avoid building new facilities for long term firm requests because one party does not have an allocationSecond: To not have unused allocations in real-time by one party while other party is restricted
Sharing of Unused Allocation During First 14 Days
Goal is to not have one party have unused allocation in real-time while other party restrictedThere would be no change in the allocation. Would recognize that one party was not going to fully utilize their allocation and it is available to other partyBoth parties would have to get back to their original allocation if congestion occurredSince the allocations have not changed, the sharing of unused allocation would be uncompensated - Use It or Lose It
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Three Situations When This Can Occur
Both parties are on the path, one with an allocation and the other with no allocation. In order to accommodate the transaction, the party with the allocation must agree to decrement for the other party’s 50% impact. If congestion occurs, the party with the allocation is responsible for 100% impacts. Must also have AFCs before approve.
Three Situations When This Can OccurThe party with no allocation is on the path, but not the other party. The party with no allocation reduces its allocation by the impact and then adds its negative allocation to the positive allocation of the other party. If net number is positive and have AFCs, can approve.
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Three Situations When This Can Occur
On a day-ahead basis, MISO and SPP will pool their unused allocations to operate a market. If MISO allocation is not fully utilized, it becomes available to SPP market. If SPP allocation is not fully utilized, it becomes available to MISO market. No AFC analysis associated with market flows.
Acquiring an Unused Allocation During Months 1 Through 18
Goal is to not have one party build new facilities in response to a long-term request because they do not have an allocationThere would be a exchange of allocation provided there are no other allocation commitments and have AFCsCredits will be given for use of allocation that can be applied to other flowgates in the same time periodLong-term firm request must be confirmed for the allocation exchange to occur. Rolled-over service based on this process will continue to create credits
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Use of Credits in Exchangefor Allocation
Only long-term firm requests can initiate an allocation exchange. This may result in creation of creditsCredits can be applied to unused allocations of the deficient entity during the same time periodA party with credits can apply these either to long-term firm requests or to obtain unused allocations even when no long-term firm request existsTo the extent credits have not been used before the time period ends, the credits expire
Example
Consider a flowgate XXYY. Its TFC is 400, its AFC is 200. MISO has an allocation of 100 and has used 90. SPP has an allocation of 300 and has used 200.
MISO gets a request on that flowgate for 50MW. They are short 40MW (100-90=10, 10-50=-40). They would provide this information to SPP, along with the queue date, as a request for a Buy Back.
SPP would use this information to determine the”value” of the capability they need as of the queue date:
40MW x ((400TFC-200AFC)/400TFC) =40MW x .5=20 Credit
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ExampleSPP would then propose to MISO a flowgate upon
which SPP would like an increased allocation in return. For example, SPP might want to trade the XXYY capacity for getting additional ZZAA capacity. ZZAA has a TFC of 1000 and an AFC of 550.
First SPP would calculate the “value”(1000-550)/1000=.45
Next, SPP would divide the credits needed by MISO on the XXYY flowgate by the “value”
20 credits/.45=44
MISO would need to grant SPP 44MW of additional allocation on the ZZAA flowgate to get 40MW of additional allocation on the XXYY flowgate.