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

Outline Introduction Statement of Work Project Status Computer Demos Conclusions

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

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

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.

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

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

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

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

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.