Facility Rating Process
MSC, Mar 2011
Agenda Item #7
Application of Transmission Ratings in
Midwest ISO Processes
Outline
• Requirements/Submission Process
– NERC/Tariff Obligation
– What/How provided
– TO Rating Methodology
• Application of ratings
– Types (Normal/Emergency)
– Planning horizon
– Forward Operations
• Outage Coordination/Assessments/Market (DA/FRAC)
– Real Time Operations
Rating Requirements/Submission Process
• NERC Requirement/Standard
– FAC -008 Facility Ratings Methodology
• Facility owner documents & provides ratings
• Tariff Obligation
– Transmission Owners Agreement – App B, Sec V
• Owners provide notification of normal and emergency rating changes for
daily/seasonal application or due to facility modifications/enhancements
• Midwest ISO applies TO submitted ratings to various models/processes
• How Rating Provided to the Midwest ISO
–
–
–
–
–
Real Time EMS Model Update Web Tool
Planning Model on Demand (MOD) Tool
Admin Model Engr Group
Model File Exchange (by exception)
Flowgate Email Exploder (Admin Transm Utilization Assessment)
Verbal/Real time operation – temp until verified (Admin RT Ops/OC)
Rating Submission/Verification Requirements
• Rating Types
– Planning (MOD)
•
•
•
•
Normal/Continuous – 4 seasons
Long-Term Emergency (LTE) – seasonal
Short-Term Emergency (STE) – seasonal
Conductor - seasonal
– Operations (EMS/AREVA)
• Normal/Continuous – 2 seasons
• Emergency/(post contingency) – seasonal/dynamic
– Flowgate – seasonal
• Rating Verification
– TO designated rating contact
Transmission Owner Rating Methodology
Midwest ISO verifies & comparably applies TO provided
ratings:
• TO rating methodology, philosophies & practices differ with
respect to rating their transmission assets
– Some TOs only have a single rating that they plan to – (normal)
– Many TOs have both Normal & either LTE and/or STE ratings.
– Some TOs employ all three ratings – (normal/LTE/STE)
•
Considerations:
– Equipment age & manufacture/design differences, risk assessment
– Equip life span/history stress variations, geographic differences
– Design application diff (line sag, expectation of wind speed, local codes,
acceptable loss of life) & line ratings defined by most limiting equipment
Application of Rating (type) - Simplified
• Normal – a continuous rating that is applicable
to system normal conditions and that if
exceeded for system normal planning studies or
operations requires an upgrade/mitigation
• LTE – rating applicable to contingency
conditions & if exceeded in planning studies or
operations requires an upgrade/mitigation unless a short-term emergency rating or
operating steps are available
Time Horizon Application of ratings
• Planning horizon – bus branch models ratings input MOD
– MTEP, Assessments, Interconnection/LT transmission Service
Studies
• Near Term/Forward Operations
– Outage Coordination, Transmission Security Planning (next day
assessments), Intra Day RT Ops look ahead Assessments – bus
branch models ratings input Web Tool
– Day Ahead and FRAC Market – node breaker models ratings
input Web Tool
– AFCs – bus branch model ratings input Flowgate Email Exploder
• Real Time Operations – node breaker EMS
network/commercial model – ratings input Web Tool (any
verbally communicated changes applied in real time but verified &
entered in the Web Tool/MOD/Flowgate Email Exploder)
Application of Transmission Ratings in
Midwest ISO Processes - Summary
• Rating Methodologies are different across TOPs but
documented/verified – NERC Std FAC 008
• Rating are provided by TOs & applied by the Midwest
ISO in reliability & market processes – Tariff
• Ratings are applied on comparable basis – verified &
updated in the planning/forward/RT processes to ensure
reliable & efficient market operation