1. Development of Damping Algorithm Olof Samuelsson Industrial Electrical Engineering and Automation Olof.Samuelsson@iea.lth.se

2. Olof Samuelsson, IEA, LTH2 Result Overview PSS using PMU-signals robust Local PSS more robust Combination comparable to local PSS System characteristics explain results On-off control of P complements PSS

3. Olof Samuelsson, IEA, LTH3 Overview Oscillations in the Icelandic system Phasor Measurement Unit signals PSS location and input signals –PMU signals, local power, combination On-off control and PSS Conclusions and future work

4. Olof Samuelsson, IEA, LTH4 The Icelandic Power System 220 kV network strong center 132 kV ring network PMU locations: Blanda 150 MW hydro Krafla 60 MW geo Sigalda 150 MW hydro

5. Olof Samuelsson, IEA, LTH5 Power Oscillations 16/2 2001 Line just east of Krafla tripped after fault Recorded and simulated Krafla MW output Recording Simulation 700 s of undamped oscillations

6. Olof Samuelsson, IEA, LTH6 PMU Output Signals Phasors V , I  Line P and Q Feedback   synchronizing  /  t   damping Communication Closing of ring 27 Feb, 2002  =  B –  S Line P  /  t Figure 12.2

7. Olof Samuelsson, IEA, LTH7 Where to Control and Measure Four post-fault situations analyzed –Line outages in 132 kV network Mode controllability of Vref and P –High at Krafla and Blanda Mode observability of  and f bus –High at Krafla and Blanda Expected from three-mass model

8. Olof Samuelsson, IEA, LTH8 PSS with  Frequency input  f to avoid f system sensitivity f Krafla –f Sigalda robust Interarea mode well damped Laxa mode destabilized Min gain 12, limited Figure 8.9 Case 34

9. Olof Samuelsson, IEA, LTH9 PSS with Power Input Figure 7.5 Robust PSS design Two lead-lag filters Interarea mode well damped Other modes also damped Min gain 18, unlimited Case 34

10. Olof Samuelsson, IEA, LTH10 Pe-PSS and  f-PSS in Parallel Pe-PSS gain set to 18 (+) Pe-PSS gain increased (x  )  f-PSS gain increased (·  ) Here  f≈  ≈Pe Figure 9.8Case 34

11. Olof Samuelsson, IEA, LTH11 Typical Simulation Low gain Pe and  f (above) comparable High gain Pe better,  f worse Combined as Pe with high gain Figure 10.23Krafla –, Blanda - -, Sigalda..Case 45

12. Olof Samuelsson, IEA, LTH12 On-off Control Complements PSS 3 MW at Blanda  f for on-off Krafla PSS linear –t=9.6 s PSS –t=4.0 s PSS+P Figure 11.2Case 34Krafla –, Blanda - -, Sigalda..

13. Olof Samuelsson, IEA, LTH13 Results Three-mass system, 2 small + 1 large  f from PMU robust input to Krafla PSS Local PSS at Krafla more robust Combination comparable to local PSS Here , Pe and  f physically equivalent On-off control of 3 MW helps PSS

14. Olof Samuelsson, IEA, LTH14 Continuations Optimize Blanda PSS Repeat with new AVR at Krafla Communication for feedback control Generator dropping and load shedding

15. Olof Samuelsson, IEA, LTH15 Phase of Blanda Machines Blanda phase 90° from Krafla –If line between plants out of service –If interarea mode damped by PSS Abnormal for power oscillations –Robust PSS design affected –P~f not effective for damping Blanda and Krafla interact –Property of system or only of model?