Event 1. Jan. 03, 2012. 01:44 GMT -34-35 No wind generation. West Texas is importing power. -36 03 Straight-Line Miles 02 370 miles 100 miles 01 280 miles 22 Steady-state angle rises. 21 20 No unit tripped. 59.90 Conclusion line trip or opening of series caps to South Texas. Easily visible throughout ERCOT. Page 1 of 11
Event 2. Jan. 03, 2012. 13:14 GMT 32 31 Good wind. 30 29 28 10 07 06 21 20 19 Strong ringdown, but steadystate angle does not change. 18 17 No unit tripped. Conclusion South Texas event, cause unknown. Page 2 of 11
Event 3. Jan. 03, 2012. 18:06 GMT 24.5 23.5 22.5 Moderate wind. Steady-state angle rises. 21.5 20.5 12 11 10 Small steady-state angle rise in the short distance between Waco and Austin. More power flowing from north to central. 27 26 25 Small drop in steady-state angle. Less power flowing from south to central. 24 23 60.10 Frequency a bit high, but no unit trip. Conclusion possible line trip to West Texas. Page 3 of 11
Event 4. Jan. 07, 2012. :55 GMT 31 30 29 Good wind. Sudden drop in steady-state angle. 28 27 10 07 06 03 02 01 00-01 Unit trip. Poor frequency recovery. 59.90 Conclusion unit trip in West Texas. Page 4 of 11
Event 5. Jan., 2012. :25 GMT 38 37 36 Strong wind. Small steadystate angle drops. 35 34 07 06 05 05 04 Steady state angle drops. 03 02 01 Unit trip. Poor frequency recovery. Conclusion unit trip in South Texas. Page 5 of 11
Event 6. Jan., 2012. :31-32 GMT 39.5 38.5 37.5 Strong wind. West Texas steady-state angle drops slightly. 36.5 35.5 30 40 50 60 70 80 90 07 Slight drop in steady-state angle, and power flowing south. 06 05 30 40 50 60 70 80 90 04 03 02 Slight angle drop in South Texas. 01 00 30 40 50 60 70 80 90 Abrupt load shedding? 30 40 50 60 70 80 90 Conclusion load shedding. Shedding was not in South Texas, and was not in West Texas. Page 6 of 11
Event 7. Jan. 10, 2012. 13:42 GMT 37.5 36.5 Strong wind. West Texas sees a bump, followed by a 10-15 sec. of undamped oscillation. 35.5 30 50 70 90 110 11 10 30 50 70 90 110 23 Zoom 22 Zoom-In Shows 0.6 Hz Oscillation 22 21 30 50 70 90 110 21 45 46 47 48 49 50 Small unit trip? Initially not a frequency event. Undamped oscillation clearly visible in frequency as well as angle. 30 50 70 90 110 Page 7 of 11 Conclusion Strong ERCOT-wide undamped oscillation, freq 0.6 Hz, lasting 20 seconds, then restarting after a pause. Most significant in South Texas, but visible everywhere. Cause unknown.
Event 8. Jan. 11, 2012. 00:59 GMT 26.5 25.5 Good wind. Steady-state angle rises. 24.5 Slight steady-state angle rise. 07 06 14 13 No significant steady-state angle change. 12 No unit tripped. 59.90 Page 8 of 11 Conclusion line trip to West Texas
Event 9. Jan. 12, 2012. 03:49 GMT 28 27 Good wind. Steady-state angle drops slightly. 26 04 Slight steady-state angle drop. 03 02 14 13 No significant change in steady-state angle. 12 Load shed? Conclusion possible load shedding Page 9 of 11
Event 10. Jan. 12, 2012. 22:24 GMT -17.5-18.5 Poor wind. Steady-state angle drops slightly. -19.5 01 00 Steady-state angle drops slightly. -01 26 25 Steady-state angle rises slightly. 24 Unit trip. Conclusion Unit trip in North or West Texas Page 10 of 11
PMU Waveform Analyzer Display for Event 7 To run the program, unzip and place the hourly files and program in one folder. When you execute the program, Pick your hour Pick your minute (default is one minute, but you can also display two or more consecutive minutes Include the PMUs in these graphs we show McDonald, UT Pan Am, and Waco. Note the line below the graph Above graph saved as XXX. That file has the points, suitable for plotting in Excel. Top right buttons do auto screen. Presently, the program takes about 30 minutes to screen one day, flagging the events of interest in an output text file. Re-run the program (no auto-screen) to view those events and create the saved text files. Have fun. Page 11 of 11