1. Enhanced State Estimation by Advanced Substation Monitoring
PIs: A. Abur & M. Kezunovic
Assistants: S. Zhong & S. Jakovljevic
Texas A&M University
PSerc Review Meeting
College Station, March 22, 2002
PSERC

2. Outline Introduction Statement of Work Project Status Computer Demos
Conclusions

3. Introduction Project Objectives Technical Approach Expected Results
Improved state estimation
Utilization of substation IEDs
Technical Approach
Merge information from substation into central state estimation
Expected Results
Prototype software for demonstration of the concepts

4. Statement of Work Two stage state estimator Substation state estimator
Formulation, implementation & testing
Substation state estimator
Matlab based simulator development
Three phase estimation
Study effects of unbalances on the state estimate; develop new solution algorithm
Documentation of results

5. Project Status
Prototype two-stage state estimator is implemented and being tested.
Substation state estimator is implemented in Matlab and being tested.
A new three phase estimator algorithm is developed and a prototype is implemented.
Utility data for testing are missing.
Actual topology error scenarios are missing.

6. Computer Demos CB/Switch Status Info Suspect 1.Stage State Topology
Error ?
1.Stage State
Estimator
Analog
Measurements N
2.Stage State
Estimator Y
Substation
Measurements
Next Scan
Estimated Status
of CB/Switches
Substation
State Estimator

7. Computer Demos Processing of Substation Measurements
Verification of circuit laws
Symmetrical components and balanced voltages check
Branch status determination
Consistency check of branch current values and topology data
Time series consistency check
Use of Matlab/Simulink
Time domain simulator
Multi or single phase models
Consistent with the external operating conditions
Substation
Measurements
Substation
State Estimator

8. Computer Demos LAV Estimator CB/Switch Status Info Suspect
Topology
Error ?
1.Stage State
Estimator
Analog
Measurements N
LAV Estimator
Automatic rejection of BD
Normalized residuals of rejected measurements
Selection of suspect substations
Next Scan

9. Computer Demos v1 v2 X = vn f1 fk Augmented State
Modified LAV Estimator
Substation Model with CBs
Flows through CBs
Zero injections at inter. nodes
CB/Switch
Status Info
Analog
Measurements v1 v2 vn f1 fk
2.Stage State
Estimator
X =
Substation
Measurements
Estimated Status
of CB/Switches
Augmented
State

10. Conclusions
Substation measurement processor is a valuable tool to enhance the SE and to monitor other substation functions.
Topology error identification is demonstrated via the prototype software.
Substation and central SE should still be integrated.
Actual scenarios and network data are missing for testing the software.
New 3-phase estimator can be implemented by using existing 1-phase estimators.