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WIT COMPUTATION OF PRIMARY INADVERTENT INTERCHANGE (ATEC)

Raymond R. Vojdani, P.E.

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WIT Computation of ATEC

Background: WECC (PWG) & OATI Have Been Working On This

Issue For About a Year The Goal Has Been to Streamline and

Standardize Computation of Primary Inadvertent Interchange (PII) Among All Balancing Authorities

The Modification to WIT Has Been Completed for Selected Three BAs (to validate the calculations)

WECC PWG Is Working With OATI to Re-compute Accumulated PII (on-peak & off-peak) for all BAs starting from July 2009***

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WIT Computation of ATEC

Highlights of Computation

Using Data in WIT (Schedules and Actuals), Uploaded Data from BAs (BA Bias, L max,) and some Constants (epsilon 10, and H ) and Data Provided by WECC Reliability Coordinator, Who is the WECC Time Monitor (Delta Time Error) WIT Computes PII As Specified in Regional Standard BAL-004-WECC-01

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WIT Computation of ATEC

Computation Cycle WIT Calculates PII 50 Minutes Past the hour

using last hour Inadvertent Interchange and last hour Delta Time Error

The PII gets added to the Accumulated PII on-peak or Accumulated PII off-peak as appropriate

Using BA’s Bias and BA’s L 10 , WIT Computes a Recommended Payback Value

Any change to schedule, or tie data will trigger a re-computation of PII from that hour beyond (Also DTE and change by WECC Admin)

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WIT Computation of ATEC

Data Provided by BAs: Bias

BA’s with fixed Bias can use the API to enter their Bias Values

BA’s with variable Bias can upload their hourly Bias value to WIT using EIDE protocol

L max The value (upper & lower limit) which a BA can

select for desired payback of Accumulated PII (bounded by BA’s L10 & 20% of BA’s Bias)

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WIT Computation of ATEC

Constants Used In the Program:

WECC Bias Value (provided by WECC Admin, currently 1999 MW/0.1Hz)

Epsilon 10 (provided by NERC, currently 6.5 mHz)

H (provided by PWG, currently 3)

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WIT Computation of ATEC

Data Provided by WECC RC Delta Time Error (DTE)

RC calculates DTE based on formula specified in the Regional standard and sends the value to WIT using EIDE

In addition, RC transmits calculated DTE value to all BAs in the WECC using ICCP

Backup DTE values are provided by two other BAs Backup (1) is provided to assure communication

security of DTE value, Backup (2) to verify calculation of DTE by RC

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WIT Computation of ATEC

What Data Will Be Available to BAs

Primary Inadvertent Accumulated Primary Inadvertent On-Peak Accumulated Primary Inadvertent Off-Peak Recommended Payback Value

Those who have OATI’s Scheduling Software, the ATEC term can be added to their NSI

These Data Can Be Transferred to BAs Using EIDE Protocol

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WIT Computation of ATEC

Demo of PII Calculation Next Step:

PII Computation is being tested by 3 BAs (AVA, AZPS, and WACM)

Once all calculations are verified, the computation will be applied for all BAs (Nov. 1, 2010 H.E.

All BAs PII will be recomputed going back to July 1, 2009.

PWG will communicate with all WECC BAs with its expectation for using WIT computation of PII.

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WIT Computation of ATEC

Issue Reporting: BAs who are currently using OATI’s webtrans

software for their back-end OASIS, they have access to OATI Problem Reporting.

https://problem.reporting.oatiinc.com Issues regarding PII computation should be

reported under WIT Project. BAs who are don’t have access to OATI’s

Problem Reporting can call OATI’s helpdesk and report the problem (763 201 2020)

In addition, issues can be sent to Anitha Neve of WECC (anitha@wecc.biz)

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WIT Computation of ATEC

That is it!!!

Any Questions ?