Academic Experience with Wide Area Sensors by Virgilio Centeno Virginia Tech PSC, Distributed Generation, Advanced Metering and Communications March 9, 2005 Clemson University

Historic Development of PMU at Virginia Tech Conceptual Development Implementation 1988 – 1990Tests on Experimental Units Transfer Technology to Industry 1992 – now Diverse Applications Model Validation Out-of Step Relaying Unit Placement State Estimation Visualization Oscillation Detection Unit Testing Error Assessment 1999 – now Wide Area frequency Measurement

1982 – 1986 Initial Concepts Expansion of algorithm derived for distance protection For computer based relays. x i x r  

E 1  1 2 E  2  2  E E 1 2 E E 1 2 E E 1 Time as a Reference

GPS Receiver: - 1Second Pulse (±100 nS) - Time Tag Time Synchronization with GPS GPS Clock: - Sampling Pulse - Accuracy reduced to 1  s ( 0.022° ) 1986 GPS not fully developed and under military control

Virginia Tech Experimental PMU First Commercial PMU ( ) Technology Transfer to Industry

1992: First Wide Area Measurement with PMUs Duke Power TVA Alabama Power Hatch Thalmann Duval Vogtle Martin Generation Substation 1992 Measurements used for Model Validation

Georgia Florida Out of step condition S-PMU Relay S-PMU Relay Main Problem: Communication Errors 9600 Baud Modem 4 wire leased telephone line Applications: Out-Of-Step Relaying

Linear state estimator Enhanced State Estimation State Measurement 1990 – Present: State Estimation Applications Algorithms for PMU Placement for Obserbability

1993- Present Dynamic Applications Unit Placement Detection of System Oscillations

Defines the interface between the GPS receiver and PMU Defines the data format of phasors being transmitted first transmitted SOC SMPCNT STAT Phasor #1 Phasor #2 Phasor #n FREQ DFREQ DIG #1 DIG #K CRC last transmitted MSBLSB DATA FORMAT IEEE standard SYNCHROPHASOR 1993 – present Standardization Efforts

(March 2003) PMU Testing

Single Phase Voltage at off-nominal Frequencies Angle vs Frequency Frequency (Hz) Angle Degrees Unit A Unit B Unit C Unit D

1992 – Present Wide Area Data Visualization

1995 – Present: New Devices and Concepts Seconds Hertz Comanche Peak Nuclear Station Full Load Rejection Test Jewett Min Hz Odessa Min Hz Venus Min Hz Robinson Min Hz     (deviation from 60Hz) Continuum Model for Power Systems Frequency Monitoring Network (FNET)

GPS Receiver A/D Converter ProcessorNIC Low Pass Filter Analog Signal Analog Signal Output Pulse Synch Time Network Card FNET - Frequency Recording Unit (FRU) Design FNET - Frequency Recording Unit (FRU) Design Measurements from any Single Phase 120Volt outlet Present: Frequency Wide Area Measurement

GPS/Internet Based Frequency Monitoring Network (FNET) Gateway Server WAN TCP/IP LAN Data Warehouse MMI Router Firewall Router Firewall WAN FRU 1 FRU n Internet User FRU 2 FRU n Internet User