FPL Transmission Reliability Margin Implementation
Document
Revision History
Rev
Changes
Author
Approver
Date
0
Initial Draft
JCR/DAMc
DAMc
3/24/11
1
Modifications to section 2 B. Minor changes
elsewhere.
AJA/DAMc
DAMc
1/11/12
2
Modification to sections 2A, 2B, and 2D
MT/DAMc
DAMc
7/16/2012
3
Specified application of L10 TRM to all horizons.
Clarifying language to how TRM is calculated
Removed TRM for FPL export to southern
DAMc
DAMc
4/12/2013
BMB
DAMc
8/9/2013
4
FPL TRMID
Revision 4
Effective Date 8/12/2013
Transmission Reliability Margin Implementation Document
(TRMID)
I. Introduction
A. Background
Florida Power and Light (FPL), as a Transmission Operator, applies a Transmission
Reliability Margin (TRM) to its transmission paths as permitted by the NERC MOD
standards (MOD-008 and MOD-028).
B. Purpose
This document serves as FPL’s TRMID and explains the methodology utilized by
FPL to calculate and use TRM for its transmission system operations.
II. TRM Calculation (MOD-008 R1, R2)
A. General
FPL uses variation in generation dispatch components of uncertainty for
individual ATC paths. This component is applied to all time intervals.
FPL’s paths involving the Southern sub-region have a contractual as well as a
physical limitation. The application of TRM on paths where Southern is the
point of receipt is described in section B of this document.
B. TRM Components (Mod-008 R1.1, R1.2)
FPL uses the following components in its TRM calculation.
Variation in Generation Dispatch (Critical Unit Offline)
This component of TRM is meant to reflect the uncertainty in generation
dispatch; specifically forced or unplanned outages of a unit that has a significant
impact on Available Transfer Capability.
The generation uncertainty component of TRM is developed from the FRCC
Transmission Working group topology model used for the TTC calculations. The
First Contingency Incremental Transfer Capability (FCITC) is determined for all
paths assuming all generating units are available and dispatched economically or
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FPL TRMID
Revision 4
Effective Date 8/12/2013
as required for local area protection as specified by the individual TOPs
(according to MOD-28 R6.1 & R6.2). New FCITC are then developed assuming
that individual generating units critical to the transfer are unavailable. The TRM
per path is the difference between the lowest FCITC with a critical unit off and the
FCITC established when the unit was dispatched.
This component of TRM is used on all posted ATC paths. The calculations are
done on an individual path basis so the allocation is 100% on that path. This
TRM is released as non-firm for all horizons.
Variation in Generation Dispatch (L10) applied to Southern Allocation
The TTC on FPL’s Southern paths is the lower of FPL’s contractual allocation or
the calculated TTC limit for the specific path. For the calculated TTC specific
path limit the TRM component described above is applied. For the contractual
import allocation a TRM based on the L10 control performance metric (BAL-0010.1a R2) is used. This TRM applies only to the contractual allocation and only on
paths where Southern is the point of receipt. This TRM is described in further
detail in the “TTC Methodology for the Southern Interface”. This contractual TRM
is applied in the scheduling, operating and planning horizons and is released as
non-firm in all horizons.
C. TRM Use and Calculation Frequencies (MOD-008 R1.3, R4)
Same Day and Real-Time (Scheduling Horizon)
The TRM applied is the Variations in Generation Dispatch component based on a
critical unit offline (Even though no hourly firm transmission is offer).
Day-Ahead and Pre-Schedule (Operating Horizon)
For the above horizon, the TRM applied is the Variations in Generation Dispatch
component based on a critical unit offline.
Beyond Day-Ahead and Pre-Schedule up to Thirteen Months (Planning Horizon)
The TRM applied is the Variations in Generation Dispatch component based on a
critical unit offline.
Calculation Frequencies
The two Variations in Generation Dispatch components of TRM are calculated by
FPL once per year.
D. TRM Communication (MOD-008 R3, R5)
FPL functions as a Transmission Service Provider and Transmission Planner as well
as a Transmission Operator. It communicates its TRM values through the posting of
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FPL TRMID
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Effective Date 8/12/2013
these values to the online reservation evaluation software to which the above entities
have access.
This TRMID is posted on FPL’s public OASIS website, the site for FRCC Operating
Entities, and will be provided, along with any underlying documentation, within 30
days of a written request by any of the following entities: Transmission Service
Providers, Reliability Coordinators, Planning Coordinators, Transmission Planners,
and Transmission Operators.
FRCC Operating Entities Posting Area- BAs/TOPs
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