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ERCOT
Nodal Protocols

Section
13:  Transmission and Distribution Losses

Updated: August 1,
2007

(Effective upon the Nodal Protocol Transition Plans Texas Nodal Market Implementation Date as prescribed
by zonal Protocol Section 21.12, Process for Transition to Nodal Market
Protocol Sections)

 

 

Transmission and Distribution
Losses

13.1 Overview

This
section sets forth the method for calculating Transmission and Distribution
Losses (T&D Losses) and responsibilities of ERCOT, Qualified Scheduling
Entities (QSEs), Transmission Service Providers (TSPs) and Distribution
Service Providers (DSPs) with respect to T&D Losses.

13.1.1 Responsibility for Transmission and Distribution
Losses

(1) T&D Losses are the responsibility of the
QSE representing the Competitive Retailers Load.  The QSE will
schedule the necessary amount of energy to cover the Competitive Retailers
Load plus the applicable T&D Losses.  ERCOT shall allocate
T&D Losses to Load at the appropriate aggregate level as part of
the data aggregation process to calculate the Load obligation of QSEs
for settlement purposes.

(2) ERCOT shall forecast Transmission Loss Factors
(TLFs) and post them to the MIS Public Area by 0600 of the Day Ahead
period.  ERCOT shall forecast the ERCOT-wide TLFs as a percentage
of Load for each Settlement Interval of the Operating Day.  By
the close of business on the day following the Operating Day, ERCOT
shall also calculate TLFs for each Settlement Interval using the actual
system Load for that Settlement Interval and shall post the resulting
deemed actual TLFs to the settlement system and the MIS Public Area.

(3) ERCOT shall forecast Settlement Interval Distribution
Loss Factors (DLFs) and post them to the MIS Public Area by 0600 of
the Day Ahead period.  ERCOT shall forecast the Settlement Interval
DLFs as a percentage of Load for each Settlement Interval of the Operating
Day.  On the day following the Operating Day, ERCOT shall also
calculate Settlement Interval DLFs using actual system Load for that
Settlement Interval and post the resulting deemed actual Settlement
Interval DLFs to the settlement system and the MIS Public Area.

(4) Distribution loss coefficients, and the calculation
methodology from which they are derived, will be subject to audit by
ERCOT for accurate and consistent application.  Non-Opt-in Entities
(NOIE) with Interval Data Recorders at the settlement point of delivery
are not required to provide Distribution loss coefficients and calculation
methodology.

(5) In the special case where there are distribution
facilities upstream from a wholesale NOIE settlement IDR, that NOIE
settlement IDR will be compensated for line and transformer losses between
the IDR and the ERCOT Transmission Grid to account for the Distribution
Losses.  The NOIE will be then treated as a transmission level
NOIE.  Calculations are subject to review by ERCOT.  Since
loss compensation is included in the wholesale settlement IDR, the TSP
and/or DSP providing upstream wheeling facilities may need to offer
wholesale wheeling tariffs excluding the losses that have already been
compensated for.

13.1.2 Calculation of Losses for Settlement

ERCOT
shall use the deemed actual Settlement Interval DLFs applicable to each
ESI ID and the deemed actual Settlement Interval TLFs when adjusting
aggregated Load for losses to determine the QSE total Load obligations.

13.2 Transmission Losses

13.2.1 Forecasted Transmission Loss Factors

(1) The forecasted TLF for each interval in the
Operating Day shall be a linear interpolation or extrapolation using
the on-peak and the off-peak TLFs and the corresponding forecast of
ERCOT System Load during the same interval to calculate the loss factors.

(2) At 0600 of the Day Ahead period, ERCOT shall
forecast a TLF for each Settlement Interval of the Operating Day and
post on the MIS Public Area the forecasted TLFs which correspond to
the Operating Day forecast.  The source of the on-peak and off-peak
losses are the ERCOT load flow base cases for the applicable month.

13.2.2 Deemed Actual Transmission Loss Factors

(1) ERCOT shall determine the deemed actual TLF
for each interval in the Operating Day, by use of a linear interpolation
or extrapolation using the on-peak and the off-peak TLFs corresponding
to the actual ERCOT System  Load during the interval.

(2) The day after the Operating Day, ERCOT shall
calculate deemed actual TLFs for each Settlement Interval of the Operating
Day and publish the TLFs to be used in settlement calculations.