State Estimator (SE)and

Simultaneous Feasibility Test (SFT)Status Report

Steve MyersManager of System Operations

State Estimator

Progress• Total difference between generation & load

reduced from 10’s of 1000’s at first to <500 MW

• Approximately 25 buses >50 MW mismatch

• 90% observability (75% with measurements)

Uses of the State Estimator

Identifying data problems Identifying model problems Monitoring of locations w/o SCADA (by

System Operators) Creating a case for Contingency

Analysis• Normally successful at least once per day

SE Plan

Continue to incrementally improve Continue to reduce mismatches With Engineer’s attention, use in Day-

Ahead analysis Train System Operators Ultimately – SE will run CA in RT

sequence

SE Plan

Needs• Data Response from QSE’s and Private

Networks• Unit Status – QSE

• Private Network Issues to Correct• Net Gen sent as one unit

• Loads not modeled

• Data required by ERCOT Operating Guides Section 8

Simultaneous Feasibility Test (SFT)

Calculates “Shift Factors” used in Congestion Management

Progress• Attempted use in December '02

• Bugs that had not shown up in test mode

• Waiting on fixes from vendor

• Once offline testing complete, will test again in production

SFT Plan

Use in Day-Ahead• Initially peak hour• Limited contingencies

Use in Hours Ahead• Initially test mode• Limited contingencies• Limited iterations with SPD

Next Steps

Contingency Analysis will run in the Real-Time sequence and upon demand

SE and SFT will run for each BES deployment

ERCOT expects its systems to be ready By April 1

What Do We Gain?

More accurate analyses – closer to RT Greatly improved pro-active CM Much more accurate “Shift Factors” Potentially less OOM deployments