Training on
Duke Energy Carolinas’ ATC
Process
Available Transfer Capability
May 24th, 2012
Agenda – High Level
• Basic Terms
• ATC Methodology
• Discussion of ATC Process
– Examples
• Wrap up
2
Basic Terms
• AFC – Available Flowgate Capability
• ATC – Available Transfer Capability
• RCPC – Remaining Contract Path Capability
• TDF – Transmission Distribution Factor
• Flowgate – A monitored pair or single element, such as a
line, or transformer, that is identified to be a potential limit.
3
ATC Methodology
• Duke Energy Carolinas uses the Flowgate Methodology
– Converted in March 2011
– Driven by significant changes in the NERC MOD standards
• Also honors tie line capability with adjacent Balancing
Authorities (BAs)
– Flowgate Methodology limited to the remaining capability of
facilities interconnecting Duke Energy Carolinas to it’s neighbors
4
ATC Calculation
ATC = Minimum
• Flowgate Methodology & RCPC operates in parallel
– Completely automated
• Process is divided into two sub-processes
– Model Builder (PowerGEM TARA AMB)
– ATC Calculator (OATi webTrans)
5
Equivalent ATC derived from Flowgate Methodology
&
Remaining Contract Path Capability (RCPC)
ATC Process – High Level
6
Model Builder
Model Builder (PowerGEM Automated Model Builder)
Model solver
RCPC
Calculation
ATC Calculator (OATi webTrans)
Calculates
Equivalent
ATC
Calculate
AFCs
Calculate
TDFs
Calculates
ATC ATCs
Flowgate Methodology Overview
7
Model
Builder
ATC
Calculator
TSRs AFCs
Flowgate
Def file
Seed
cases
Gen
Dispatch
NERC Tag Dump (NERC IDC)
Tags
Load
Forecasts
NERC SDX (System Data Exchange)
Transmission
& Generation
Outages
OASIS (OATi webOASIS)
TSRs ATC
System Data
AFCs
Coordinating FTP Sites (CPL, PJM, SC, SCEG,SOCO, TAP, TVA, YAD)
TSRs
FTP Site (OATi FTP Site)
RTDF
File
Model Builder
8
Model Builder
Model Builder (PowerGEM Automated Model Builder)
Model solver
GSFs
Baseflows
RTDF
File
Flowgate def file
Seed cases
Gen Dispatch
To FTP Site
What does the Model Builder do?
• Automatically creates & solves many models
• Consolidates output data into a single file
Tag Dump
Load
Forecasts
Transmission
Outages
Generation
Outages
Model Builder
• Building Models
– Builds a model for each increment of series
• e.g. Hourly48_no tags builds 48 models representing the next 48
hours
– Starts with applicable seed case
– Modifies seed case with input data
• Load, transmission & generation outages, as well as tags (only in
the Hourly48 models)
– Dispatches generation to meet load + interchange + losses
• Utilizes dispatch files
• Respects generation outages and reserve shut downs
9
Model Builder – Description of Model Series
• Model Builder schedule
10
Model Series # of Models
Created
Model
Increment Creation Schedule
Hourly 48_no tags 48 Hourly Every hour
Hourly 48 48 Hourly Every hour
Hourly 180 Hourly Runs up to 4 x daily
Daily 45 Daily Runs up to 3 x daily
Monthly 13 Monthly Runs up to 3 x daily
Creates 48 unique models specific to each hour
Model Builder – Hourly 48_no tags Example
11
Seed Case
Model
representing
05/25/12 00:00
Outages on
05/25/12
00:00
Load Forecast
for 05/25/12
00:00
Seed Case
Model
representing
05/25/12 01:00
Outages on
05/25/12
01:00
Load Forecast
for 05/25/12
01:00
Seed Case
Model
representing
05/25/12 02:00
Outages on
05/25/12
02:00
Load Forecast
for 05/25/12
02:00
Seed Case
Model
representing
05/27/12 00:00
Outages on
05/27/12
00:00
Load Forecast
for 05/27/12
00:00
Same Seed Case
Load Specific
to each hour
Outages
Specific to
each hour
Model Builder – Seed Case
• Seed cases
– Utilize cases developed by SERC Near-Term Study Group
• Developed quarterly for next 5 seasons
• Cases built with participation from all SERC Transmission Providers
• Heavily coordinated development
• Same cases used in Duke’s old Contract Path methodology
– Modified to align with NERC tools that provide load & outage
data
• NERC System Data Exchange (SDX)
• NERC Interchange Distribution Calculator (IDC)
12
Model Builder – Outages
• Outages imported from NERC System Data Exchange
(SDX)
– Automatically queries & downloads data every hour
• CPLE,CPLW, DUK, PJM, SC, SCEG, SEHA, SERU, SETH, SOCO,
TVA, TAP, & YAD
– Generation outages (typically 20 MWs +)
– Transmission outages (100 kV +)
• Apply outage criteria
– Hourly
– Daily
– Monthly
– RCPC
13
ATCID has detailed description of
outage criterion. Link to ATCID
Model Builder – Outage Criteria
• Hourly48, Hourly48_no tags, & Hourly outage criteria
– Generator outages
• Typically greater than 20 MWs
• Short-Standby (SS) units considered as outaged
– Transmission outages
• Must be greater than or equal to 100 kV
• If all of the above criteria is met, the outaged facility is
modeled out of service each hour, between the outage
start & stop time
14
Model Builder – Outage Criteria (hourly example)
• For example: Jackson Ferry – Antioch 500 kV line
– Outaged 05/25/12 08:00 – 05/25/12 16:00
15
Made up scenario
05/25/12 08:00
Model
Line out-service
05/25/12 06:00
Model
Line in-service
05/25/12 07:00
Model
Line in-service
05/25/12 09:00
Model
Line out-service
05/25/12 15:00
Model
Line out-service
05/25/12 16:00
Model
Line in-service
Each hourly model has the line modeled
out-of-service during the outage period
• Daily outage criteria
– In order for an outage to be modeled as out-of-service in the
daily model, the generation or transmission outage must:
• Have an outage duration of at least 2 hrs in the “Daily Peak Period”
• Typically greater than 20 MWs (generators)
• Be greater than or equal to 100 kV (transmission)
– Daily Peak Period
• 8 hour window
Model Builder – Outage Criteria
16
Outage must be at least 2
hours long in the 8 hour
long “Daily Peak Period”.
Model Builder – Outage Criteria (daily example)
• For example: Jackson Ferry – Antioch 500 kV line
– Outaged 05/25/12 08:00 – 05/25/12 16:00
17
Made up scenario
05/24/12 Model
Line in-service
05/25/12 Model
Line out-service
05/26/12 Model
Line in-service
00:00 12:00 16:00 20:00 00:00 04:00 08:00
Jackson Ferry – Antioch 500 kV Outage
Daily Peak Period
outage window
Outage overlaps the Daily
Peak Period by 4 hours. > Required
2 hours
Model Builder – Outage Criteria (daily example)
• For example: Newport - Richmond 500 kV line
– Outaged 05/25/12 06:00 – 05/25/12 13:00
18
Made up scenario
05/24/12 Model
Line in-service
05/25/12 Model
Line in-service
05/26/12 Model
Line in-service
00:00 12:00 16:00 20:00 00:00 04:00 08:00
Newport - Richmond 500 kV Outage
Daily Peak Period
outage window
Outage overlaps the Daily
Peak Period by 1 hour. < Required
2 hours
• Monthly outage criteria
– In order for an outage to be modeled as out-of-service in the
monthly model, the generation or transmission outage must:
• Be outaged on the “Representative Day”
• Have an outage duration of at least 2 hrs in the “Daily Peak Period”
• Typically greater than 20 MWs (generators) & 100 kV or greater
(transmission)
– Representative Day
• 3rd Wednesday of the month
– Daily Peak Period
• 8 hour window
Model Builder – Outage Criteria
19
Outage must be on the “Representative
Day” AND at least 2 hours long in the 8
hour long “Daily Peak Period”.
Model Builder – Outage Criteria (monthly example)
• For example: Jackson Ferry – Antioch 500 kV line
– Outaged 05/01/12 08:00 – 05/15/12 16:00
20
04/12 Model
Line in-service
05/12 Model
Line in-service
06/12 Model
Line in-service
May 1 May 15 May 20 May 25 May 5 May 10
Jackson Ferry – Antioch 500 kV Outage
Representative Day
outage window
Outage does not occur on
“Representative Day”
Made up scenario
Model Builder – Outage Criteria (monthly example)
• For example: Newport - Richmond 500 kV line
– Outaged 05/16/12 08:00 – 05/16/12 16:00
21
04/12 Model
Line in-service
05/12 Model
Line out-service
06/12 Model
Line in-service
May 1 May 15 May 20 May 25 May 5 May 10
Newport - Richmond 500 kV Outage
Representative Day
Made up scenario
00:00 12:00 16:00 20:00 00:00 04:00 08:00
Daily Peak Period
Newport – Richmond 500 kV Outage
Model Builder – Outage Criteria
• This is what the transmission outage data looks like
22
Outage Criteria Example
• Initial conditions
– Generator A = 1500 MW
– Generator B = 250 MW
– Load B = 750 MW
• This reservation is used in the planning models, but can be
tagged/scheduled at a lower level in the operating horizon.
– Rating of Station A-B ckt 1&2 are 500 MWs/line
• We want to know the baseflow or initial AFC on Flowgate
# 42444, Station A-B 1 flo Station A-B 2 for the Month of
May.
23
Outage Criteria Example – Initial Conditions
24
Station A
A
Station B
B
AFC monthly base flow for May 2012
42444 Station A-B 1 flo Station A-B 2 = 500 – 250 - .5(250) = 125
Flowgate A-B ckt 1
Flowgate A-B ckt 2
1,500 MWs 250 MWs
500 MWs
500 MWs
250 MWs
250 MWs
750 MWs
Flowgate A-B ckt 1 rating = 500
Flowgate A-B ckt 2 rating = 500
Outage Criteria Example – Apply Outage
• How does a maintenance outage at Station B affect our
initial monthly AFCs for the month of May on flowgate
42444?
25
Outage Criteria Example
26
Station A
A
Station B
B
Generator B maintenance schedule
5/14 08:00 – 5/21 23:59
Flowgate A-B ckt 1
Flowgate A-B ckt 2
1,500 MWs 0 MWs
375 MWs
375 MWs
375 MWs
375 MWs
750 MWs
Flowgate A-B ckt 1 rating = 500
Flowgate A-B ckt 2 rating = 500
AFC monthly base flow for May 2012
42444 Station A-B 1 flo Station A-B 2 = 500 – 375 - .5(375) = -62.5
Outage Criteria Example
• We now know that monthly AFCs for the month of May
are negative due to this generator outage, but how do our
initial AFCs look as we get closer to the scheduled
outage window?
27
Outage Criteria Example
• Daily Firm/Non-Firm AFC
28
Date AFC
5/12 125
5/13 125
5/14 -62.5
5/15 -62.5
5/16 -62.5
5/17 -62.5
5/18 -62.5
5/19 -62.5
5/20 -62.5
5/21 -62.5
5/22 125
5/23 125
5/24 125
5/25 125
Outage Criteria Example
• Hourly Planning Firm/Non-Firm AFC from 5/14 at 00:00
29
Date AFC
5/14 0000 125
5/14 0100 125
5/14 0200 125
5/14 0300 125
5/14 0400 125
5/14 0500 125
5/14 0600 125
5/14 0700 125
5/14 0800 -62.5
5/14 0900 -62.5
5/14 1000 -62.5
5/14 1100 -62.5
5/14 1200 -62.5
5/14 1300 -62.5
Outage Criteria Example
• Load B decides that it is not going to need the firm
transaction and decides to release 500 MW of this firm for
5/14. How does this change the AFC that is being
calculated?
30
Outage Criteria Example
31
Station A
A
Station B
B
Generator B maintenance schedule
5/14 0800 – 5/21 2359
Flowgate A-B ckt 1
Flowgate A-B ckt 2
1,500 MWs 0 MWs
625 MWs
625 MWs
125 MWs
125 MWs
250 MWs
Flowgate A-B ckt 1 rating = 500
Flowgate A-B ckt 2 rating = 500
AFC monthly base flow for May 2012
42444 Station A-B 1 flo Station A-B 2 = 500 – 125 - .5(125) = 312.5
Outage Criteria Example
• Hourly Operating Firm/Non-Firm AFC from 5/14 at 00:00
32
Date
5/14 0000
5/14 0100
5/14 0200
5/14 0300
5/14 0400
5/14 0500
5/14 0600
5/14 0700
5/14 0800
5/14 0900
5/14 1000
5/14 1100
5/14 1200
5/14 1300
AFC Non-Firm
312.5
312.5
312.5
312.5
312.5
312.5
312.5
312.5
312.5
312.5
312.5
312.5
312.5
312.5
AFC Firm
125
125
125
125
125
125
125
125
-62.5
-62.5
-62.5
-62.5
-62.5
-62.5
Outage Criteria Example – Questions?
• Completed walk-thru of the outage criteria example
problem
– Up next: Model Builder – Load Forecasts
33
Model Builder – Load Forecasts
• Load imported from NERC System Data Exchange (SDX)
– Automatically queries & downloads data every hour
– CPLE,CPLW, DUK, PJM, SC, SCEG, SEHA, SERU, SETH,
SOCO, TVA, TAP, & YAD
• For PJM, load imported from file provided by PJM
– Breaks out load forecasts for each of PJM’s legacy Balancing
Authorities
– Automatically downloads data every hour
– Increases model accuracy
34
Model Builder – Load Forecast
• This is what the hourly load data looks like
35
Model Builder – Generation Dispatch
• Duke Energy Carolinas generation dispatch
– Block Dispatch File
• Groups units into blocks based on dispatch order
– Direct Dispatch Files
• Pumped Storage (based on Duke unit commitment 7-day outlook
forecast)
• IPPs – Based on tags in hourly operating horizon
• Adjacent TSP generation dispatch
– Block Dispatch File (provided by adjacent TSP)
– Direct Dispatch Files (if provided)
36
Model Builder
37
Model Builder
Model Builder (PowerGEM Automated Model Builder)
Model solver
GSFs
Baseflows
RTDF
File
Flowgate def file
Seed cases
Gen Dispatch
To FTP Site Tag Dump
Load
Forecasts
Transmission
Outages
Generation
Outages
We just went over
building models
Model Builder
38
Model Builder
Model Builder (PowerGEM Automated Model Builder)
Model solver
GSFs
Baseflows
RTDF
File
Flowgate def file
Seed cases
Gen Dispatch
To FTP Site Tag Dump
Load
Forecasts
Transmission
Outages
Generation
Outages
We will now look at solving
models & output data
Model Builder
• Solving Models & Output Data
– Solves each model
• AC solution with internal Decoupled Newton Solution algorithm
– Calculates for each model:
• Baseflow on every flowgate
• Generation Shift Factors (GSFs)
– For each flowgate with respect to each POR/POD
– Combines Baseflow & GSF data into single output file
• RTDF file
39
Model Builder – Questions?
• Completed walk-thru of Model Builder
– Up next: ATC Calculator
40
Flowgate Methodology Overview
41
Model
Builder
ATC
Calculator
TSRs AFCs
Flowgate
Def file
Seed
cases
Gen
Dispatch
NERC Tag Dump (NERC IDC)
Tags
Load
Forecasts
NERC SDX (System Data Exchange)
Transmission
& Generation
Outages
OASIS (OATi webOASIS)
TSRs ATC
System Data
AFCs
Coordinating FTP Sites (CPL, PJM, SC, SCEG,SOCO, TAP, TVA, YAD)
TSRs
FTP Site (OATi FTP Site)
RTDF
File
ATC Calculator
42
RCPC
Calculation
ATC Calculator (OATi webTrans)
Calculates
Equivalent
ATC
Flowgate def file
AFCs from
Adjacent TPs
RTDF Files
TSRs from
Adjacent TPs
TSRs from
Duke OASIS
Tags from
webTag
Calculate
AFCs
Calculate
TDFs
Calculates
ATC
TRM & CBM
data
AFCs
ATCs
TSRs
To OASIS
To FTP
Site
Remaining Contract Path Capability (RCPC)
• Very similar to the old Area Interchange Methodology
(a.k.a. Contract Path Methodology)
• Respects tie line capability with adjacent BAs
• Reflects the capacity remaining on those tie lines
– Includes the impact of:
• TRM – Transmission Reliability Margin
• Reservations/schedules
43
Remaining Contract Path Capability (RCPC)
44
RCPC
Calculation
ATC Calculator (OATi webTrans Software)
OASIS (OATi webOASIS)
TSRs
Tagging System (OATi webTag)
Tags OATi
OATi
Manual Process
Interface Ratings
to Adjacent BAs
(MWs)
TRM
(MWs)
Automated Process
Remaining Contract Path Capability (RCPC)
45
Interface Ratings
to Adjacent BAs
(MWs)
Summation of facility ratings interconnecting
Duke to each adjacent BA
DUK PJM
DUK-PJM Interface Rating
2003 MWs
Tie line #2 – Rating = 130 MWs
For Example:
Tie line #1 – Rating = 1,873 MWs
RCPC Calculation
Firm Equation
RCPC = Contract Path (CP) Limit – TRM – CBM - Firm TSRs
Non-Firm Equation – Prior to 08:00 day prior
RCPC = CP Limit – TRM – CBM –Firm TSRs –Non-Firm TSRs
Non-Firm Equation – After 08:00 day prior
RCPC = CP Limit – TRM – CBM – Scheduled Firm – Non-Firm TSRs
Facilitates the release of unscheduled-firm capacity to the non-firm RCPC
Scheduled Firm = Capacity of firm reservation that
is tagged (transmission profile)
46
RCPC Calculation
• Wheel-Through Paths
– RCPC is the minimum of the two import/export paths that
comprise the wheel-through path
– For example, PJM-SOCO wheel-through path:
47
DUK PJM SOCO
PJM SOCO
RCPC = 2,003 MWs RCPC = 2,499 MWs
RCPC = 2,003 MWs
PJM-SOCO contract path Is the
minimum of PJM-DUK & DUK-SOCO
RCPC Calculation Questions?
• Completed walk-thru of RCPC
48
RCPC
Calculation
ATC Calculator (OATi webTrans)
Calculates
Equivalent
ATC
Calculate
AFCs
Calculate
TDFs
Calculates
ATC
– Up next: ATC Calculator
ATC Calculator – Calculate TDFs
• Calculate Transfer Distribution Factors (TDFs)
– Performed for every flowgate with respect to every path
– Based on the RTDF file imported from the Model Builder
• Uses the GSFs from the RTDF file
• TDF = GSFPOR – GSFPOD
– Expressed as a percentage (%)
49
TDF Example Problem
• Lets take a look at flowgate x and how the TDFs affect
this flowgate
50
DUK CPLW
DUK – CPLW
Flowgate x
TDF Example Problem
• Basic Principle
– In order to do a Duke to CPLW transfer, we have to increase
generation in Duke and decrease generation in CPLW.
– When we do this, the AFC process looks at the Generation Shift
Factor (GSF) for each flowgate defined in AFC process and
calculates the % impact of moving that generation.
51
TDF Example Problem
• The GSFs associated with a POR of DUK is “DUK_R” and
a POD of CPLW is “CPLW_D”
• The AFC process then calculates a TDF for flowgate x
with respect to the DUK-CPLW path
– TDF = GSFPOR-GSFPOD
– For our example, it would be:
• TDFflowgate x | for DUK-CPLW = GSFPOR (DUK_R) – GSFPOD (CPLW_D)
52
TDF Example Problem
• In this example, we are:
– Increasing generation in DUK and decreasing generation in
CPLW, analyzing the affects this has on flowgate x
53
DUK CPLW
DUK - CPLW
Flowgate x
TDF Example Problem
• The GSF from webTrans for DUK_R = 0.010260
• The GSF from webTrans for CPLW_D = -0.091550
54
Flowgate x
Flowgate x
TDF Example Problem
• Remember:
– TDFflowgate x | for DUK-CPLW = GSFPOR (DUK_R) – GSFPOD (CPLW_D)
– Using the numbers from webTrans:
• TDFflowgate x | for DUK-CPLW = 0.010260 – (-0.091550)
• TDFflowgate x | for DUK-CPLW = 0.010260 + 0.091550
• TDFflowgate x | for DUK-CPLW = 0.101736 = 10.1736%
55
TDF Example Problem
• What does it all mean?
– At 10% TDF, The AFC number calculated in the AFC process for
a DUK-CPLW transfer would be used whether it is an internal
flowgate (>3%) or an external flowgate (>5%).
– This is done for all defined flowgates in the AFC process with
respect to the DUK-CPLW path
56
TDF Example Problem – Questions?
• Completed walk-thru of TDF Example Problem
– Up next: ATC Calculator – Calculate AFCs
57
ATC Calculator – Calculate AFCs
• Firm AFC equation
– AFCFirm = TFC – CBM – TRM – Baseflow – FRESN
• Non-Firm AFC equation (Prior to 08:00 day prior)
– AFCNon-Firm = TFC – CBM – TRM – Baseflow – FRESN – NFRES
• Non-Firm AFC equation (After 08:00 day prior)
– AFCNon-Firm = TFC – CBM – TRM – Baseflow* – NFRES*
* NFRES – Non-firm reservations only impact ATC for a short time or until they are tagged. Baseflow term contains impacts of
firm & non-firm tags.
Where: TFC = Total Flowgate Capability
FRESN = Firm reservation impacts
NFRES = Non-firm reservation impacts
58
ATC Calculator – Calculate AFCs
• Coordinated AFC Values
– AFCs calculated by adjacent Transmission Providers for their
flowgates honored in the Duke ATC process
– Supersedes Duke’s calculated values
• Duke’s calculated values only used if coordinating entity has not
provided any values
– Required by FERC mandatory NERC MOD Reliability Standard
• R5.3 “For external Flowgates, identified in R2.1.4, use the AFC
provided by the Transmission Service Provider that calculates AFC
for that Flowgate.” (NERC MOD-030-02)
59
ATC Calculator – Calculate Equivalent ATC
Equivalent ATCP = Minimum
Where: ATCp = Available Transfer Capability on path p
AFCn = Available Flowgate Capability of flowgate n
TDFn,p = Transfer Distribution Factor for flowgate n with respect to
path p.
NOTE: The Equivalent ATC calculation only considers flowgates that are “impacted” by the path p. In other
words, the TDF of flowgate n must be at or above 3% for internal flowgates and 5% for external
flowgates.
60
𝐴𝐹𝐶1
𝑇𝐷𝐹1, 𝑝
,𝐴𝐹𝐶2
𝑇𝐷𝐹2, 𝑝
,𝐴𝐹𝐶3
𝑇𝐷𝐹3, 𝑝
, … 𝐴𝐹𝐶𝑛
𝑇𝐷𝐹𝑛, 𝑝
ATC Calculator – Calculate ATC
ATC = Minimum
ATC posted to OASIS for each path
– Located in System Data
– Firm & non-firm ATC for each posted path
61
Remaining Contract Path Capability (RCPC)
&
Equivalent ATC derived from Flowgate Methodology
ATC Calculator – Questions?
• Completed walk-thru of ATC Calculator
62
RCPC
Calculation
ATC Calculator (OATi webTrans)
Calculates
Equivalent
ATC
Calculate
AFCs
Calculate
TDFs
Calculates
ATC
Comments on ATC
ATC • Driven by RCPC & Equivalent ATC
Equivalent ATC • Driven by AFC & TDF
TDF • Driven by outages & load/Gen dispatch
AFC
63
• Driven by baseflow
& market activity
Why are AFC numbers so different from one
horizon to another?
• There are several reasons AFC can change
– Generation/Transmission Outages
• Scheduled and forced outages can have a drastic impact on AFC
calculations
– Load forecast
• Due to weather forecast changes, this can have a drastic impact on
the generation mix used not only for Duke, but for our neighboring
BAs as well. This will have an impact on the base flow and TDF
calculations.
– Adjacent Transmission Provider coordinated flowgates
64
For More Information…
• Available Transfer Capability Implementation Document
(ATCID)
– http://www.oatioasis.com/DUK/DUKdocs/Current_Available_Tra
nsfer_Capability_Implementation_Document_-_ATCID.pdf
• Attachment C of the OATT
– http://www.oatioasis.com/DUK/DUKdocs/DukeCarolinaOATT.pdf
• January 19, 2012 Stakeholder ATC Training Presentation
– http://www.oatioasis.com/DUK/DUKdocs/Q4_20120119_-
_ATC_Training_Presentation.pptx
• ATC Methodology Contact
– (651) 632-8708
65
Questions?
• Any questions about the material we just went over?
• Do you have questions/concerns about the ATC process
in general?
• Was this training session of value to you?
66