1. WIT Computation of Primary Inadvertent Interchange (ATEC)
Raymond R. Vojdani, P.E.

2. 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***

3. 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

4. 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)

5. 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)

6. 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)

7. 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

8. 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

9. 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.

20. 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.
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 ( )
In addition, issues can be sent to Anitha Neve of WECC

21. WIT Computation of ATEC
That is it!!!
Any Questions ?